DEC H7260 PSU fault

Jon Elson elson at
Sat Jan 27 19:11:19 CST 2018

On 01/27/2018 02:43 PM, Jules Richardson via cctalk wrote:
> Well, there's someone's hand-written sticker on the top 
> saying it's a lowly RD51 - however the actual p/n sticker 
> says it's an RD53-A and the defect table lists it as 
> ST506, 85MB.
> Of course it probably doesn't work anyway ;-)
The likelihood of a 30+ year old MFM hard drive working is 
pretty small.  If it DOES work, get the data off it as soon 
as possible, the grease in the bearings are likely to have 
turned into gunk and it won't last.
>> If you start with just the M7606 - CPU and the M7608 - 
>> 4MB ram once
>> you get a console cable built it shouldn't be too hard to 
>> get some
>> basic signs of life.
> Yes, that's where I'm at right now...
> Console default is 8 data bits, 1 stop bit and no parity 
> (at whatever speed the switch is set to), correct?
> I'm getting an alternating F and 9 on the hex LED diag 
> display on the console panel, no output at all on my 
> terminal, and the M7606 starts with 4 solid red LEDs, then 
> a solid green, then the middle pair of the red LEDs start 
> a simultaneous slow flash on/off (while the outer two plus 
> the green remain steady)
MM, that doesn't sound good at all.  The single LED on the 
console panel is supposed to count down from F as it runs 
through the on-board diags.  It is supposed to send a 2-line 
(I think) description of the board rev level and ROM 
firmware level, and then do something like this:

F.....E.....D.....C....B.....A.....9.....8....7  (this is 
the memory test, and can take a LONG time) and then continue,
finally leaving you with a console prompt or a boot or boot 
failure message.


More information about the cctalk mailing list