>> -----Oorspronkelijk bericht-----
>> Van: cctalk [mailto:cctalk-bounces at classiccmp.org] Namens Terry
Stewart
>> Verzonden: dinsdag 22 december 2015 21:50
>> Aan: General Discussion: On-Topic and Off-Topic Posts
>> Onderwerp: Piggybacking 74LS logic chips to confirm a suspected fault
>>
>> Hi,
>>
>> I've written up my recent third Apple II repair, this time an Apple IIe.
>>
http://www.classic-computers.org.nz/blog/2015-12-22-appleiIIe-no-video.htm
>>
>> One interesting aspect of this repair is that piggy-backing a logic
chip helped
>> confirm a faulty one. I'd only ever used this technique with RAM.
>> I'm sure it only works if the chip has a particular type of fault,
but it worked this
>> time for me.
>>
>> Terry (Tez)
>
> I use a HP 10529A logic comparator on regular basis for fault finding
in ttl circuits.
> It compares a reference chip with the CUT (Chip under test;) it's a
very nice diagnostic tool.
> It's a bit like piggy backing just a little more sophisticated :0
>
> -Rik
In my experience, the type of socket you used is quite unreliable and
will tend to develop bad contacts. There is a reason they are cheap... I
would use a turned pin type socket instead, e g an Augat socket. They
will not let you down. More expensive, but considering the work involved
in replacing a socket and the risk of messing up the PCB, the cost is
negligible.
Jonas
BAMA is probably the best known site for old test equipment and amateur radio manuals, followed by Ebaman.
Dale H. Cook, GR / HP Collector, Roanoke/Lynchburg, VA
http://plymouthcolony.net/starcity/radios/index.html
> From: Guy Sotomayor
> It's typical of most of the vintage gear. Folks save the CPUs and ditch
> the peripherals.
It's not entirely sloth and stupidity, though. Disk drives in particular
(usually the biggest issue in this area) are complex precision machinery that
operate at very high speeds, etc, and working on them is a formidable job,
and requires specialized parts which are, in general, no longer available.
> I think the biggest problem is that there isn't a spec per-se on
> Massbus. A lot of reverse engineering will be required to make it work
> properly in all cases.
If it were done, though, that would be wonderful, especially for people with
PDP-11/70's; the UNIBUS on those machines is reputedly the slowest of any
PDP-11, so having mass storage on the MASSBUS is really necessary for good
performance. (Apologies for my -11 centrism in an IBM-focused thread... :-)
But finding the connectors (and probably the cables too) is going to be a
cast-iron nightmare. Maybe we could settle on an alternative (the way I think
we should switch to pairs of dual cards with Berg/DuPont headers, with
standard flat cables between them, to replace the now-unobtainable BC11-A's -
DEC showed this works, with the M9014/M9042..)
Noel
Is there anything like Appleworks 1.0 for the commodore 64? if so could
you be kind enough to give me the name of the program? I have searched
but have found nothing of any value. I just would like a checkbool
ledger and a savings spreadsheet.
Not too long ago I picked up a DEC Venturis FX 5120. It contains a 3COM
3C905-TX network card. There are some sites around the web that purport to
have drivers for this card, but I am very wary of downloading anything from
these sites.
Does anyone happen to have drivers for this card? I am not sure what OSs
this card was supported on, so any drivers at all would be appreciated.
Thanks
Rob
Hi all,
I just signed up today and haven't been admitted to the group, so I couldn't
reply to the appropriate message. But, in browsing through recent messages I
saw the one with a link to loads of manuals. My first thought was that if that
was interesting, this one would be too. Manuals for tons of old test equipment.
http://bama.edebris.com/manuals/
Will
Lots more work on the PDP-12 at the RICM. We got an RS-232 console board
and baud rate generator from Vincent and now have both serial ports
working. Warren modified Kyle's SerialDisk and we booted OS/8 from an
emulated RK05 on the second serial port. We fixed one of the bus interface
boards in the DW8E Omnibus expansion chassis, and connected the RX8E/RX02.
We were able to boot OS/8 from an RX01 diskette. We replaced an M160
flip-chip and now the EAE instructions work. We replaced an M103 flip-chip
and the KW12 clock works. This system is new enough that ECO EM12-0055 for
the KW12 was installed when it was built. This means that the KW12 Maindecs
earlier than D8CD will not work. We cleaned up the PC04 paper tape
reader/punch and connected it to the PC8E. The punch works OK, but the
reader does not always step correctly and does not read the tape correctly.
Fixing this will be the next project.
Once we get the PC04 working the next project will be the RK8E/RK05.
Out of frustration we set aside fixing the TC12 LINCtape controller. We see
spikes on data track #3 that corrupt the data. We swapped the TU56 for a
known good TU55, swapped the data/control cable, and swapped every
flip-chip that is related to data track #3. Nothing has eliminated the
spikes. The only part that we have not swapped is the backplane wiring
between the data cable and the G882 flip-chips. Warren has a plan to
temporarily replace that.
We found that the maintenance prints that came with the system do not
include ECO EM12-0055.
Does anyone have a set of KW12 prints that include ECO EM12-0055?
--
Michael Thompson
Hi,
I've written up my recent third Apple II repair, this time an Apple IIe.
http://www.classic-computers.org.nz/blog/2015-12-22-appleiIIe-no-video.htm
One interesting aspect of this repair is that piggy-backing a logic chip
helped confirm a faulty one. I'd only ever used this technique with RAM.
I'm sure it only works if the chip has a particular type of fault, but it
worked this time for me.
Terry (Tez)
Folks,
I own an EAI TR-10 analog computer which sadly came without any patch cables
and accessories. Normally this wouldn't be a problem, BUT the TR-10 comes
with special resistive plugs which go at the ends of the patch leads. These
have a 4mm plug and socket with a 10k or 100k resistor in between. I can't
figure out a way to easily fabricate replacements. I can easily obtain 4mm
plugs and sockets, and solder a resistor between them, but when I try and
mount them on a short rigid tube all my efforts fail. The plug and socket
need to be twisted in opposite directions and any soldered joint just fails.
Any usggestions?
Does any one have some of these and if so how are they constructed?
Dave Wade
G4UGM
