2 Jul
2025
2 Jul
'25
7:08 a.m.
Dear list members,
I was wondering if anybody is aware of VAX 86x0 schematics having survived the product
life cycle within DEC? I searched the web extensively but could not find any hints on
this.
It seems that DEC never published such details as schematics for the successor of the VAX
11/78x systems, not even on microfiche, maybe due to the macrocell array implementation
(just a guess). All I could find is that there were illustrated parts list on
microfiche.
However, maybe Hewlett Packard handed DEC-internal documents over to a museum such as the
CHM? Or a former designer still have schematics in their archives?
Any pointers would be greatly appreciated!
Best regards,
Pierre
-----------------------------------------------------------------------------
http://www.digitalheritage.de
2 Jul
2 Jul
7:28 a.m.
On 02/07/2025 12:08, P Gebhardt via cctalk wrote:
Dear list members,
I was wondering if anybody is aware of VAX 86x0 schematics having survived the product
life cycle within DEC? I searched the web extensively but could not find any hints on
this.
It seems that DEC never published such details as schematics for the successor of the VAX
11/78x systems, not even on microfiche, maybe due to the macrocell array implementation
(just a guess). All I could find is that there were illustrated parts list on microfiche.
However, maybe Hewlett Packard handed DEC-internal documents over to a museum such as the
CHM? Or a former designer still have schematics in their archives?
Any pointers would be greatly appreciated!
Best regards,
Pierre
-----------------------------------------------------------------------------
http://www.digitalheritage.de
I have the VAX 8600 Training Print Set and I sent it to someone (sorry,
forgot who) years ago.
There's at least one online version here:
https://www.vaxhaven.com/images/0/04/EY-4818E-PP-0001.pdf
I don't know what, if anything, would be the difference between this and
the normal MPxxxx drawings.
Antonio
--
Antonio Carlini
antonio(a)acarlini.com
8:34 a.m.
There's a VAX8600 for sale here in Germany, not on Ebay or any other
platform, but on personal mediation only. I have tried several times to
have it sold, but no success yet. I am only the agent and do not receive
any commission. I only want to have it salvaged from rotting in the barn
where it is stored.
Let me know if you're interested.
Antonio Carlini via cctalk <cctalk(a)classiccmp.org> schrieb am Mi., 2. Juli
2025, 13:44:
On 02/07/2025 12:08, P Gebhardt via cctalk wrote:
Dear list members,
I was wondering if anybody is aware of VAX 86x0 schematics having
survived the product life cycle within DEC? I searched the web extensively
but could not find any hints on this.
It seems that DEC never published such details as
schematics for the
successor of the VAX 11/78x systems, not even on microfiche, maybe due to
the macrocell array implementation (just a guess). All I could find is that
there were illustrated parts list on microfiche.
However, maybe Hewlett Packard handed
DEC-internal documents over to a
museum such as the CHM? Or a former designer still have schematics in their
archives?
Any pointers would be greatly appreciated!
Best regards,
Pierre
-----------------------------------------------------------------------------
I have the VAX 8600 Training Print Set and I sent it to someone (sorry,
forgot who) years ago.
There's at least one online version here:
https://www.vaxhaven.com/images/0/04/EY-4818E-PP-0001.pdf
I don't know what, if anything, would be the difference between this and
the normal MPxxxx drawings.
Antonio
--
Antonio Carlini
antonio(a)acarlini.com
6 Jul
6 Jul
8:55 a.m.
There's a VAX8600 for sale here in Germany, not on
Ebay or any other
platform, but on personal mediation only. I have tried several times to
have it sold, but no success yet. I am only the agent and do not receive
any commission. I only want to have it salvaged from rotting in the barn
where it is stored.
Let me know if you're interested.
Dear Ullrich,
the VAX that you are talking about is exactly the VAX that I would like to give a
new permanent and good home, with the intention to bring it back to life.
It will join VAX 11/750, VAX 6000 and VAX 7000 systems plus cluster
interconnect technology.
I have been in contact with the people around this system for the last weeks
and we are in the process of organizing everything required to make things
happen. This system is only 3 hours away from where I live.
I am seeking the documentation "situation" and thus asked the list if there
are any more technical documentation such as schematics in existence
in addition to what is on bitsavers.
With best regards,
Pierre
www.digitalheritage.de
2 Jul
2 Jul
9:26 a.m.
On Jul 2, 2025, at 7:28 AM, Antonio Carlini via cctalk
<cctalk(a)classiccmp.org> wrote:
I have the VAX 8600 Training Print Set and I sent it to someone (sorry, forgot who) years
ago.
There's at least one online version here:
https://www.vaxhaven.com/images/0/04/EY-4818E-PP-0001.pdf
I don't know what, if anything, would be the difference between this and the normal
MPxxxx drawings.
Antonio
That looks a bit like a block diagram, sort of a conceptual level schematic as opposed to
a detailed gate by gate schematic.
It reminds me a bit of the "block diagram" manuals for the CDC 6600
supercomputer, which shows most of the logic modules and the buses interconnecting them,
along with the relevant clock pulses (more or less accurately). But there are also the
wiring diagrams, which are the actual fully completed schematics. If you want to
understand the machine, the block diagrams are excellent; if you want to replicate it,
they are not sufficient and the wiring diagrams are actually what you need.
paul
10:49 a.m.
We have an 8650 at the Rhode Island Computer Museum. Unfortunately I don't
think that there is any home of getting it running again.
https://www.ricomputermuseum.org/collections-gallery/equipment/dec-vax-8650
On Wed, Jul 2, 2025 at 10:14 AM Paul Koning via cctalk <
cctalk(a)classiccmp.org> wrote:
--
Michael Thompson
On Jul 2, 2025, at 7:28 AM, Antonio Carlini via
cctalk <
cctalk(a)classiccmp.org> wrote:
I have the VAX 8600 Training Print Set and I sent it to someone (sorry,
forgot who) years ago.
There's at least one online version here:
https://www.vaxhaven.com/images/0/04/EY-4818E-PP-0001.pdf
I don't know what, if anything, would be the difference between this and
the normal MPxxxx drawings.
Antonio
That looks a bit like a block diagram, sort of a conceptual level
schematic as opposed to a detailed gate by gate schematic.
It reminds me a bit of the "block diagram" manuals for the CDC 6600
supercomputer, which shows most of the logic modules and the buses
interconnecting them, along with the relevant clock pulses (more or less
accurately). But there are also the wiring diagrams, which are the actual
fully completed schematics. If you want to understand the machine, the
block diagrams are excellent; if you want to replicate it, they are not
sufficient and the wiring diagrams are actually what you need.
paul
6 Jul
6 Jul
8:59 a.m.
Hello Michael,
We have an 8650 at the Rhode Island Computer Museum.
Unfortunately I don't
think that there is any home of getting it running again.
https://www.ricomputermuseum.org/collections-gallery/equipment/dec-vax-8650
--
Michael Thompson
What are the reasons to believe that there is only little hope for the one at RICM?
Did you start to work on getting it up and running?
Indeed, if the boards are faulty, then it will be challenging to fix them or find
replacements, I guess.
Best regards,
Pierre
-----------------------------------------------------------------------------
http://www.digitalheritage.de
10:54 a.m.
Pierre,
We don’t have the power, cooling, or space in our display area to run the 11/780 or the
8650. We don’t have any spare boards for either machine, which would make debugging
difficult. It looks like they will remain display pieces.
On Jul 6, 2025, at 9:05 AM, P Gebhardt via cctalk
<cctalk(a)classiccmp.org> wrote:
Hello Michael,
We have an 8650 at the Rhode Island Computer
Museum. Unfortunately I don't
think that there is any home of getting it running again.
https://www.ricomputermuseum.org/collections-gallery/equipment/dec-vax-8650
--
Michael Thompson
What are the reasons to believe that there is only little hope for the one at RICM?
Did you start to work on getting it up and running?
Indeed, if the boards are faulty, then it will be challenging to fix them or find
replacements, I guess.
Best regards,
Pierre
-----------------------------------------------------------------------------
http://www.digitalheritage.de
8:27 p.m.
On 7/6/25 09:54, Michael Thompson via cctalk wrote:
Pierre,
We don’t have the power, cooling, or space in our display area to run the 11/780
The great thing about the 780 was that (aside from fixed
control store) there were no exotic chips in it. Almost any
IC in the machine was standard 74S, 74AS or 74F series
logic. So, you could keep one running for a LONG time with
just chip swapping. And, of course, the machine was shipped
with a HUGE print set, about 2-3 inches thick of 11 X 17 sheets.
The power dissipation wasn't that huge, also.
Jon
8:57 a.m.
On Jul 2,
2025, at 7:28 AM, Antonio Carlini via cctalk <cctalk(a)classiccmp.org> wrote:
I have the VAX 8600 Training Print Set and I sent it to someone (sorry, forgot who) years
ago.
There's at least one online version here:
https://www.vaxhaven.com/images/0/04/EY-4818E-PP-0001.pdf
I don't know what, if anything, would be the difference between this and the normal
MPxxxx drawings.
Antonio
That looks a bit like a block diagram, sort of a conceptual level schematic as opposed to
a detailed gate by gate schematic.
It reminds me a bit of the "block diagram" manuals for the CDC 6600
supercomputer, which shows most of the logic modules and the buses interconnecting them,
along with the relevant >clock pulses (more or less accurately). But there are also
the wiring diagrams, which are the actual fully completed schematics. If you want to
understand the machine, the block >diagrams are excellent; if you want to replicate it,
they are not sufficient and the wiring diagrams are actually what you need.
paul
8:46 a.m.
Dear Antonio,
thank you very much for your link!
I kindly appreciate it.
With best regards,
Pierre
-----------------------------------------------------------------------------
http://www.digitalheritage.de
Am Mittwoch, 2. Juli 2025 um 11:44:53 GMT hat Antonio Carlini via cctalk
<cctalk(a)classiccmp.org> Folgendes geschrieben:
On 02/07/2025 12:08, P Gebhardt via cctalk wrote:
Dear list members,
I was wondering if anybody is aware of VAX 86x0 schematics having survived the product
life cycle within DEC? I searched the web extensively but could not find any hints on
this.
It seems that DEC never published such details as schematics for the successor of the VAX
11/78x systems, not even on microfiche, maybe due to the macrocell array implementation
(just a guess). All I could find is that there were illustrated parts list on microfiche.
However, maybe Hewlett Packard handed DEC-internal documents over to a museum such as the
CHM? Or a former designer still have schematics in their archives?
Any pointers would be greatly appreciated!
Best regards,
Pierre
-----------------------------------------------------------------------------
http://www.digitalheritage.de
I have the VAX 8600 Training Print Set and I sent it to someone (sorry,
forgot who) years ago.
There's at least one online version here:
https://www.vaxhaven.com/images/0/04/EY-4818E-PP-0001.pdf
I don't know what, if anything, would be the difference between this and
the normal MPxxxx drawings.
Antonio
--
Antonio Carlini
antonio(a)acarlini.com
2 Jul
2 Jul
11:13 a.m.
On 7/2/25 06:08, P Gebhardt via cctalk wrote:
Dear list members,
I was wondering if anybody is aware of VAX 86x0 schematics having survived the product
life cycle within DEC? I searched the web extensively but could not find any hints on
this.
It seems that DEC never published such details as schematics for the successor of the VAX
11/78x systems, not even on microfiche, maybe due to the macrocell array implementation
(just a guess). All I could find is that there were illustrated parts list on microfiche.
However, maybe Hewlett Packard handed DEC-internal documents over to a museum such as the
CHM? Or a former designer still have schematics in their archives?
Any pointers would be greatly appreciated!
I did have a KA630-AA print set at one time. That was about
the latest prints I have seen.
Jon
12:25 p.m.
On Jul 2, 2025, at 11:13 AM, Jon Elson via cctalk
<cctalk(a)classiccmp.org> wrote:
On 7/2/25 06:08, P Gebhardt via cctalk wrote:
That makes some sense. Print sets were needed in older machines because FE would actually
replace failed components on a board. With "swap the failed board" repair
procedures, it isn't all that useful for support engineers to know how a board works,
much less what the detailed circuitry looks like.
paul
Dear list members,
I was wondering if anybody is aware of VAX 86x0 schematics having survived the product
life cycle within DEC? I searched the web extensively but could not find any hints on
this.
It seems that DEC never published such details as schematics for the successor of the VAX
11/78x systems, not even on microfiche, maybe due to the macrocell array implementation
(just a guess). All I could find is that there were illustrated parts list on microfiche.
However, maybe Hewlett Packard handed DEC-internal documents over to a museum such as the
CHM? Or a former designer still have schematics in their archives?
Any pointers would be greatly appreciated!
I did have a KA630-AA print set at one time. That was about the latest prints I have
seen.
Jon
8:48 p.m.
On 7/2/25 11:25, Paul Koning via cctalk wrote:
Yes, we had an FE replace components on an 11/45. But, they
certainly NEVER did component-level repairs on an 11/780 or
uVAX-II.
Jon
On Jul 2, 2025, at 11:13 AM, Jon Elson via cctalk
<cctalk(a)classiccmp.org> wrote:
On 7/2/25 06:08, P Gebhardt via cctalk wrote:
That makes some sense. Print sets were needed in older machines because FE
would actually replace failed components on a board. With "swap the failed
board" repair procedures, it isn't all that useful for support engineers to know
how a board works, much less what the detailed circuitry looks like. Dear list members,
I was wondering if anybody is aware of VAX 86x0 schematics having survived the product
life cycle within DEC? I searched the web extensively but could not find any hints on
this.
It seems that DEC never published such details as schematics for the successor of the VAX
11/78x systems, not even on microfiche, maybe due to the macrocell array implementation
(just a guess). All I could find is that there were illustrated parts list on microfiche.
However, maybe Hewlett Packard handed DEC-internal documents over to a museum such as the
CHM? Or a former designer still have schematics in their archives?
Any pointers would be greatly appreciated!
I did have a KA630-AA print set at one
time. That was about the latest prints I have seen.
Jon 
3 Jul
3 Jul
1:20 a.m.
Same here. The FE came prepared with a replacement board. Never repaired the board.
In and out!
Sent from my iPhone
On Jul 2, 2025, at 17:55, Jon Elson via cctalk
<cctalk(a)classiccmp.org> wrote:
On 7/2/25 11:25, Paul Koning via cctalk wrote:
That makes some sense. Print sets were needed in older machines because FE would
actually replace failed components on a board. With "swap the failed board"
repair procedures, it isn't all that useful for support engineers to know how a board
works, much less what the detailed circuitry looks like.
Yes, we had an FE replace components on an 11/45. But, they certainly NEVER did
component-level repairs on an 11/780 or uVAX-II.
Jon
On Jul 2,
2025, at 11:13 AM, Jon Elson via cctalk <cctalk(a)classiccmp.org> wrote:
On 7/2/25 06:08, P Gebhardt via cctalk wrote:
Dear list members,
I was wondering if anybody is aware of VAX 86x0 schematics having survived the product
life cycle within DEC? I searched the web extensively but could not find any hints on
this.
It seems that DEC never published such details as schematics for the successor of the VAX
11/78x systems, not even on microfiche, maybe due to the macrocell array implementation
(just a guess). All I could find is that there were illustrated parts list on
microfiche.
However, maybe Hewlett Packard handed DEC-internal documents over to a museum such as the
CHM? Or a former designer still have schematics in their archives?
Any pointers would be greatly appreciated!
I did have a KA630-AA print set at one time. That was about the latest prints I
have seen.
Jon
2 p.m.
Same here. The FE came prepared with a replacement
board. Never repaired the board.
In and out!
Which makes sense. My guess is in the 80's 90's they would send the
board back to a rework facility and repair it there. BGA/PGA is not too
difficult to do if you have a good rework station, and the rest of the
chips on the board were probably worth enough to make the rework totally
feasable.
By the mid 2000's, yeah they probably would just trash the board.
C
2:15 p.m.
On Jul 3, 2025, at 2:00 PM, cz via cctalk
<cctalk(a)classiccmp.org> wrote:
I remember a rework/repair facility in our company around 2005 or so. I'm not sure
how long it lasted after that.
As for rework stations, I have one, inherited from a disk drive company that closed in
2001. "BGA 3000". I think all it needs is a camera, which I once had but I
think let someone borrow and it disappeared. That's part of a system to do accurate
positioning of surface mount chips onto the board. I wonder if a GoPro or the like could
be put into service for that task.
paul
Same here. The FE came prepared with a
replacement board. Never repaired the board.
In and out!
Which makes sense. My guess is in the 80's 90's they would send the board back to
a rework facility and repair it there. BGA/PGA is not too difficult to do if you have a
good rework station, and the rest of the chips on the board were probably worth enough to
make the rework totally feasable.
By the mid 2000's, yeah they probably would just trash the board.
2:59 p.m.
As for rework stations, I have one, inherited from a
disk drive company that closed in 2001. "BGA 3000". I think all it needs is a
camera, which I once had but I think let someone borrow and it disappeared. That's
part of a system to do accurate positioning of surface mount chips onto the board. I
wonder if a GoPro or the like could be put into service for that task.
Probably. One of the secrets to hot air rework is that if you use
preheat and a good flux the bga and really small smd components will
"auto align" as long as they are close to accurate. When that last bit
of soft hot air is added the solder goes liquid and surface tension both
pulls the component into line and (in the case of BGA) makes all the
little balls round so there are no solder joints between pins. Flux
ensures this, then you let it cool and problem is solved.
So yes a camera and magnifier is nice for super accuracy, but not really
needed. YMMV.
C
2:26 p.m.
That’s a good business practice anyway. You want your high price system up and running as
fast as possible, so not having to do more than cursory diagnostics is a good thing I
think deck realize that with the VAX and it’s remote the diagnostic capability as for the
board breaks, IBM used to do that for all the boards they replaced. They even had a
special board breaking tool.
My CE from IBM said that it costs IBM more to diagnose a faulty board than it does to make
a new one so that’s why they do it. Breaking the board also ensures that the engineers
won’t get caught up in a side project trying to figure out what went wrong.
Sent from my iPhone
On Jul 3, 2025, at 11:10, cz via cctalk
<cctalk(a)classiccmp.org> wrote:
Same here. The FE came prepared with a replacement board. Never repaired the board.
In and out!
Which makes sense. My guess is in the 80's 90's they would send the board back to
a rework facility and repair it there. BGA/PGA is not too difficult to do if you have a
good rework station, and the rest of the chips on the board were probably worth enough to
make the rework totally feasable.
By the mid 2000's, yeah they probably would just trash the board.
C
3:52 p.m.
On Jul 3, 2025, at 2:26 PM, Wayne S via cctalk
<cctalk(a)classiccmp.org> wrote:
That’s a good business practice anyway. You want your high price system up and running as
fast as possible, so not having to do more than cursory diagnostics is a good thing I
think deck realize that with the VAX and it’s remote the diagnostic capability as for the
board breaks, IBM used to do that for all the boards they replaced. They even had a
special board breaking tool.
My CE from IBM said that it costs IBM more to diagnose a faulty board than it does to
make a new one so that’s why they do it. Breaking the board also ensures that the
engineers won’t get caught up in a side project trying to figure out what went wrong.
That's true for problems seen occasionally. When people realize a particular issue
appears "too often" it does become an engineering matter, because then it
indicates an issue with design or manufacturing or part selection.
For example, I remember a product that had a memory backup battery issue, which turned out
to be a change in plating for the battery holder. For engineering it turned into an
exercise in learning what "electrovoltaic series" means -- not something
familiar to most digital logic EEs.
paul
4:12 p.m.
Yes, stats are kept about issues.
Someone should look at the stats and start to investigate when there’s a lot of failures
with the same issue. Explicit instructions should be sent to field engineers to take extra
steps to document what they found and how it was resolved, and report their conclusions
back to the investigation leader.
That’s how IBM did it.
I know DEC kinda did it for software on VMS though their “Software and Solutions”
database. I really liked looking at that.
Sent from my iPhone
On Jul 3, 2025, at 12:52, Paul Koning
<paulkoning(a)comcast.net> wrote:
On Jul 3, 2025, at 2:26 PM, Wayne S via cctalk
<cctalk(a)classiccmp.org> wrote:
That’s a good business practice anyway. You want your high price system up and running as
fast as possible, so not having to do more than cursory diagnostics is a good thing I
think deck realize that with the VAX and it’s remote the diagnostic capability as for the
board breaks, IBM used to do that for all the boards they replaced. They even had a
special board breaking tool.
My CE from IBM said that it costs IBM more to diagnose a faulty board than it does to
make a new one so that’s why they do it. Breaking the board also ensures that the
engineers won’t get caught up in a side project trying to figure out what went wrong.
That's true for problems seen occasionally. When people realize a particular issue
appears "too often" it does become an engineering matter, because then it
indicates an issue with design or manufacturing or part selection.
For example, I remember a product that had a memory backup battery issue, which turned
out to be a change in plating for the battery holder. For engineering it turned into an
exercise in learning what "electrovoltaic series" means -- not something
familiar to most digital logic EEs.
paul
4:29 p.m.
On 2025-07-03 16:12, Wayne S via cctalk wrote:
Yes, stats are kept about issues.
Someone should look at the stats and start to investigate when there’s a lot of failures
with the same issue. Explicit instructions should be sent to field engineers to take extra
steps to document what they found and how it was resolved, and report their conclusions
back to the investigation leader.
That’s how IBM did it.
I know DEC kinda did it for software on VMS though their “Software and Solutions”
database. I really liked looking at that.
Sent from my iPhone
> On Jul 3, 2025, at 12:52, Paul Koning<paulkoning(a)comcast.net> wrote:
>
>
>
>> On Jul 3, 2025, at 2:26 PM, Wayne S via cctalk<cctalk(a)classiccmp.org>
wrote:
>>
>> That’s a good business practice anyway. You want your high price system up and
running as fast as possible, so not having to do more than cursory diagnostics is a good
thing I think deck realize that with the VAX and it’s remote the diagnostic capability as
for the board breaks, IBM used to do that for all the boards they replaced. They even had
a special board breaking tool.
>> My CE from IBM said that it costs IBM more to diagnose a faulty board than it
does to make a new one so that’s why they do it. Breaking the board also ensures that the
engineers won’t get caught up in a side project trying to figure out what went wrong.
> That's true for problems seen occasionally. When people realize a particular
issue appears "too often" it does become an engineering matter, because then it
indicates an issue with design or manufacturing or part selection.
>
> For example, I remember a product that had a memory backup battery issue, which
turned out to be a change in plating for the battery holder. For engineering it turned
into an exercise in learning what "electrovoltaic series" means -- not something
familiar to most digital logic EEs.
>
> paul
>
Stats are very important if the manufacturer has a lot of their own
product under comprehensive maintenance agreements, especially fixed
disk drives that would require major time to recover from backups when
they fail. Control Data had a problem once, I believe it was with the
MMDs, where they noticed premature failures in the field. Because they
kept accurate records, they were able to trace it back to serials after
a particular date when a water filter had been changed at the factory
and the new one caused some sort of problem with the epoxy holding the
magnetic material to the substrate.
cheers
Nigel
--
Nigel Johnson, MSc., MIEEE, MCSE VE3ID/G4AJQ/VA3MCU
Amateur Radio, the origin of the open-source concept!
Skype: TILBURY2591
7:02 p.m.
We had some Fujitsu Eagles with that exact same problem.
Go figure.
Sent from my iPhone
On Jul 3, 2025, at 13:39, Nigel Johnson Ham via cctalk
<cctalk(a)classiccmp.org> wrote:
On 2025-07-03 16:12, Wayne S via cctalk wrote:
Yes, stats are kept about issues.
Someone should look at the stats and start to investigate when there’s a lot of failures
with the same issue. Explicit instructions should be sent to field engineers to take extra
steps to document what they found and how it was resolved, and report their conclusions
back to the investigation leader.
That’s how IBM did it.
I know DEC kinda did it for software on VMS though their “Software and Solutions”
database. I really liked looking at that.
Sent from my iPhone
>> On Jul 3, 2025, at 12:52, Paul Koning<paulkoning(a)comcast.net> wrote:
>
>
>
>> On Jul 3, 2025, at 2:26 PM, Wayne S via cctalk<cctalk(a)classiccmp.org>
wrote:
>>
>> That’s a good business practice anyway. You want your high price system up and
running as fast as possible, so not having to do more than cursory diagnostics is a good
thing I think deck realize that with the VAX and it’s remote the diagnostic capability as
for the board breaks, IBM used to do that for all the boards they replaced. They even had
a special board breaking tool.
>> My CE from IBM said that it costs IBM more to diagnose a faulty board than it
does to make a new one so that’s why they do it. Breaking the board also ensures that the
engineers won’t get caught up in a side project trying to figure out what went wrong.
> That's true for problems seen occasionally. When people realize a particular
issue appears "too often" it does become an engineering matter, because then it
indicates an issue with design or manufacturing or part selection.
>
> For example, I remember a product that had a memory backup battery issue, which
turned out to be a change in plating for the battery holder. For engineering it turned
into an exercise in learning what "electrovoltaic series" means -- not something
familiar to most digital logic EEs.
>
> paul
>
Stats are very important if the manufacturer has a lot of their own product under
comprehensive maintenance agreements, especially fixed disk drives that would require
major time to recover from backups when they fail. Control Data had a problem once, I
believe it was with the MMDs, where they noticed premature failures in the field. Because
they kept accurate records, they were able to trace it back to serials after a particular
date when a water filter had been changed at the factory and the new one caused some sort
of problem with the epoxy holding the magnetic material to the substrate.
cheers
Nigel
--
Nigel Johnson, MSc., MIEEE, MCSE VE3ID/G4AJQ/VA3MCU
Amateur Radio, the origin of the open-source concept!
Skype: TILBURY2591
10:28 p.m.
On Thu, Jul 3, 2025 at 4:19 PM Wayne S via cctalk <cctalk(a)classiccmp.org> wrote:
Yes, stats are kept about issues.
Someone should look at the stats and start to investigate when there’s a lot of failures
with the same issue. Explicit instructions should be sent to field engineers to take extra
steps to document what they found and how it was resolved, and report their conclusions
back to the investigation leader.
I remember the DEC-20 at Ohio State. It had a TU77 tape drive. This
was back in the days of paper Operator Logs. One day, it went like
this:
09:23 TU77 catches fire
09:24 TU77 puts itself out
09:35 TU77 won't load tapes, Called Field Service.
When they called, the convo went something like, "you have a TU77 on
fire? We'll be right out." No additional questions. FS Engineer
comes out with one satchel, opens the tape drive, pops out one board,
pops in a replacement from his satchel, and the drive comes back to
life.
Clearly not his first barbeque.
-ethan
11:48 p.m.
Wow. Do you remember if the board was in the tape unit itself or the TM03?
My guess would be the FETs that control the tape motors shorting and
turning into a fireball. Still cool as hell :-)
CZ
(Had a TU77 at home. Never caught fire)
On 7/3/2025 10:28 PM, Ethan Dicks via cctalk wrote:
On Thu, Jul 3, 2025 at 4:19 PM Wayne S via cctalk
<cctalk(a)classiccmp.org> wrote:
Yes, stats are kept about issues.
Someone should look at the stats and start to investigate when there’s a lot of failures
with the same issue. Explicit instructions should be sent to field engineers to take extra
steps to document what they found and how it was resolved, and report their conclusions
back to the investigation leader.
I remember the DEC-20 at Ohio State. It had a TU77 tape drive. This
was back in the days of paper Operator Logs. One day, it went like
this:
09:23 TU77 catches fire
09:24 TU77 puts itself out
09:35 TU77 won't load tapes, Called Field Service.
When they called, the convo went something like, "you have a TU77 on
fire? We'll be right out." No additional questions. FS Engineer
comes out with one satchel, opens the tape drive, pops out one board,
pops in a replacement from his satchel, and the drive comes back to
life.
Clearly not his first barbeque.
-ethan
4 Jul
4 Jul
11:07 a.m.
On 7/3/25 21:28, Ethan Dicks via cctalk wrote:
On Thu, Jul 3, 2025 at 4:19 PM Wayne S via cctalk
<cctalk(a)classiccmp.org> wrote:
We had a TU77 on a VAX 11/780. (Should have waited for the
TU78.) Anyway, the early ones had a bad heat problem.
DEC added a rack of boxer fans to the rear door that
exhausted air over a heat exchanger to cool the bearing
air. This greatly helped, but there was still an issue when
tape was running fast through the drive, like for backups.
The tape head got hot and the tape would start sticking to
the scraper blades and head.
Otherwise, it was a fine drive. Made bu Pertec, I think the
T1000 model.
Jon
Yes, stats are kept about issues.
Someone should look at the stats and start to investigate when there’s a lot of failures
with the same issue. Explicit instructions should be sent to field engineers to take extra
steps to document what they found and how it was resolved, and report their conclusions
back to the investigation leader.
I remember the DEC-20 at Ohio State. It had a
TU77 tape drive. This
was back in the days of paper Operator Logs. One day, it went like
this:
09:23 TU77 catches fire
09:24 TU77 puts itself out
09:35 TU77 won't load tapes, Called Field Service.
When they called, the convo went something like, "you have a TU77 on
fire? We'll be right out." No additional questions. FS Engineer
comes out with one satchel, opens the tape drive, pops out one board,
pops in a replacement from his satchel, and the drive comes back to
life.
Clearly not his first barbeque. 
6 Jul
6 Jul
2:21 p.m.
On 7/4/25 11:07, Jon Elson via cctalk wrote:
We had a TU77 on a VAX 11/780. (Should have waited
for the TU78.)
Maybe not. IIRC, the TU78 had a bunch of teething problems. I
definitely remember many 2 AM phone calls from the night shift operators
when the overnight backup runs failed (I think the tape would run off
the end of the reel). Much back and forth with the DEC hardware and VMS
engineers before it finally got fixed.
Gary
4:15 p.m.
On 7/6/2025 2:21 PM, Gary Grebus via cctalk wrote:
On 7/4/25 11:07, Jon Elson via cctalk wrote:
I seem to remember a number of tapes that would do that in those days.
Anybody here ever use an Exatron Stringy Floppy. Didn't run off the
reel because it was like an 8-track. But it would happily loop all the
way around and write over the beginning of the tape making it unusable.
:-)
bill
We had a TU77 on a VAX 11/780. (Should have
waited for the TU78.)
Maybe not. IIRC, the TU78 had a bunch of teething problems. I
definitely remember many 2 AM phone calls from the night shift operators
when the overnight backup runs failed (I think the tape would run off
the end of the reel). Much back and forth with the DEC hardware and VMS
engineers before it finally got fixed.
8:34 p.m.
On 7/6/25 13:21, Gary Grebus via cctalk wrote:
On 7/4/25 11:07, Jon Elson via cctalk wrote:
We had a very early TU77, and went through a bunch of issues
with it, TOO! mostly due to tape overheating and sticking
to the heads. You could hear it from the next room, a
pop-pop-pop every time the tape started moving. Cleaning
the heads every 3-4 tapes during backup.
Jon
We had a TU77 on a VAX 11/780. (Should have
waited for
the TU78.)
Maybe not. IIRC, the TU78 had a bunch of teething
problems. I definitely remember many 2 AM phone calls
from the night shift operators when the overnight backup
runs failed (I think the tape would run off the end of the
reel). Much back and forth with the DEC hardware and VMS
engineers before it finally got fixed. 
4 Jul
4 Jul
4:23 a.m.
On 03/07/2025 20:52, Paul Koning via cctalk wrote:
Folks,
I must say the chaos continues. I recently had the steering wheel
changed on my VW Tiguan, apparently a common occurrence.
I kept bleeping and telling me that "travel assist" wasn't available and
you couldn't disable the very loud beep.
There must be some design issue with the capacitive "buttons" or some
sort of wiring short....
... however chatting to the parts guy about some other bits he said it
must have cost VW a lot as it took them a while to trace the fault and
fix the wheels design.
.. in the meantime some cars went through multiple wheels....
Dave
G4UGM
On Jul 3, 2025, at 2:26 PM, Wayne S via cctalk
<cctalk(a)classiccmp.org> wrote:
That’s a good business practice anyway. You want your high price system up and running as
fast as possible, so not having to do more than cursory diagnostics is a good thing I
think deck realize that with the VAX and it’s remote the diagnostic capability as for the
board breaks, IBM used to do that for all the boards they replaced. They even had a
special board breaking tool.
My CE from IBM said that it costs IBM more to diagnose a faulty board than it does to
make a new one so that’s why they do it. Breaking the board also ensures that the
engineers won’t get caught up in a side project trying to figure out what went wrong.
That's true for problems seen occasionally. When people realize a particular
issue appears "too often" it does become an engineering matter, because then it
indicates an issue with design or manufacturing or part selection.
For example, I remember a product that had a memory backup battery issue, which turned
out to be a change in plating for the battery holder. For engineering it turned into an
exercise in learning what "electrovoltaic series" means -- not something
familiar to most digital logic EEs.
paul
2:22 a.m.
On 03/07/2025 19:00, cz via cctalk wrote:
Well the Honeywell 6000 & Level 66 series machines
https://gunkies.org/wiki/Honeywell_6000_series
came with a board tester which was supposed to identify a faulty IC but
I can't remember how successful it was. I seem to remember L66 boards
were about 12"/30cms square and mostly TTL or MOS Memory.
the CE dropped the board into the tester which told him which chip to
change..
I think the most changed chips were RAM.
Same here. The
FE came prepared with a replacement board. Never
repaired the board.
In and out!
Which makes sense. My guess is in the 80's
90's they would send the
board back to a rework facility and repair it there. BGA/PGA is not
too difficult to do if you have a good rework station, and the rest of
the chips on the board were probably worth enough to make the rework
totally feasable.
By the mid 2000's, yeah they probably would just trash the board.
C
Dave
2:34 a.m.
Early Honeywell boards were wire-wrap so they could easily be updated in
the field. The board tester we had read test vectors from punched cards and
stopped reading cards when it found a fault. The tester had a display for
the card number. The FE looked up the test and card number and the chart
said which chip had failed. It was not good at finding intermittent faults.
On Fri, Jul 4, 2025, 2:29 AM David Wade via cctalk <cctalk(a)classiccmp.org>
wrote:
On 03/07/2025 19:00, cz via cctalk wrote:
Well the Honeywell 6000 & Level 66 series machines
https://gunkies.org/wiki/Honeywell_6000_series
came with a board tester which was supposed to identify a faulty IC but
I can't remember how successful it was. I seem to remember L66 boards
were about 12"/30cms square and mostly TTL or MOS Memory.
the CE dropped the board into the tester which told him which chip to
change..
I think the most changed chips were RAM.
Same
here. The FE came prepared with a replacement board. Never
repaired the board.
In and out!
Which makes sense. My guess is in the 80's
90's they would send the
board back to a rework facility and repair it there. BGA/PGA is not
too difficult to do if you have a good rework station, and the rest of
the chips on the board were probably worth enough to make the rework
totally feasable.
By the mid 2000's, yeah they probably would just trash the board.
C
Dave
3 Jul
3 Jul
10:21 a.m.
On Jul 2, 2025, at 8:48 PM, Jon Elson via cctalk
<cctalk(a)classiccmp.org> wrote:
On 7/2/25 11:25, Paul Koning via cctalk wrote:
Yes, we had an FE replace components on an 11/45. But, they certainly NEVER did
component-level repairs on an 11/780 or uVAX-II.
Jon
The last one I remembered was an 11/45 also, an MMU data path failure. We (Josh Rosen and
I) diagnosed it while waiting for the DEC FE to show up. Josh pointed to a particular
chip (we had found a stuck bit somewhere in the MMU) and Jim asked why that particular
chip. The answer "because that's the most expensive one in the signal
path". Jim said "we'll see" but shortly afterwards pulled out his
parts box, soldering iron, and solder sucker to remove -- yes indeed -- that particular
chip. :-)
Once DIP chips started being replaced by PGA or other hard to replace parts, replacing
them on site became impractical. I suspect someone also did the economics analysis to
show that carrying a set of boards, diagnosing to the failed board only, and swapping the
board in question was faster and easier.
Of course it led to jokes like this one:
FE is driving down the highway. Suddenly, the ride gets very rough. He mutters
"must be a flat tire", pulls over, puts on the spare. He drives away, car still
goes "bump bump bump". He grumbles "I guess it wasn't that tire"
and pulls over again to swap one of the other tires.
paul
On Jul 2, 2025, at 11:13 AM, Jon Elson via cctalk
<cctalk(a)classiccmp.org> wrote:
On 7/2/25 06:08, P Gebhardt via cctalk wrote:
That makes some sense. Print sets were needed in older machines because FE
would actually replace failed components on a board. With "swap the failed
board" repair procedures, it isn't all that useful for support engineers to know
how a board works, much less what the detailed circuitry looks like. Dear list members,
I was wondering if anybody is aware of VAX 86x0 schematics having survived the product
life cycle within DEC? I searched the web extensively but could not find any hints on
this.
It seems that DEC never published such details as schematics for the successor of the VAX
11/78x systems, not even on microfiche, maybe due to the macrocell array implementation
(just a guess). All I could find is that there were illustrated parts list on microfiche.
However, maybe Hewlett Packard handed DEC-internal documents over to a museum such as the
CHM? Or a former designer still have schematics in their archives?
Any pointers would be greatly appreciated!
I did have a KA630-AA print set at one
time. That was about the latest prints I have seen.
Jon
6 Jul
6 Jul
9:07 a.m.
On Jul 2,
2025, at 11:13 AM, Jon Elson via cctalk <cctalk(a)classiccmp.org> wrote:
On 7/2/25 06:08, P Gebhardt via cctalk wrote:
That makes some sense. Print sets were needed in older machines because FE would actually
replace failed components on a board. With "swap the failed board" repair
procedures, it >isn't all that useful for support engineers to know how a board
works, much less what the detailed circuitry looks like.
paul Dear list members,
I was wondering if anybody is aware of VAX 86x0 schematics having survived the product
life cycle within DEC? I searched the web extensively but could not find any hints on
this.
It seems that DEC never published such details as schematics for the successor of the VAX
11/78x systems, not even on microfiche, maybe due to the macrocell array
>implementation (just a guess). All I could find is that there were illustrated parts
list on microfiche.
However, maybe Hewlett Packard handed DEC-internal documents over to a museum such as the
CHM? Or a former designer still have schematics in their archives?
Any pointers would be greatly appreciated!
I did have a KA630-AA print set at one time. That was about the latest prints I have
seen.
Jon
13
days inactive
18
days old
33 comments
13 participants
participants (13)
-
Antonio Carlini -
Bill Gunshannon -
cz -
David Wade -
Ethan Dicks -
Gary Grebus -
Hans-Ulrich Hölscher -
Jon Elson -
Michael Thompson -
Nigel Johnson Ham -
P Gebhardt -
Paul Koning -
Wayne S