30 May
2004
30 May
'04
10:36 a.m.
At 21:04 30/05/2004 +0100, you wrote:
Agreed - I could easily put in a PC supply, and I even have a couple from
"slimline" PC's which would probably fit the box - however I want the
machine
to be as original as possible.
It is - the only IC is the Opto-isolator.
Anyway - I found the problem - It was a shorted capacitor on the primary side
of the transformer - what threw me off was it was NOT one of the electrolytics...
There's another one beside it which is just like it, so I think I will replace
both.
Supply works fine now - and so does the entire machine.
(Joy at getting an old Apple clone working somewhat overshadowed by the fact
that I finally found a Kaypro today!)
Regards,
Dave
--
dave04a (at) Dave Dunfield
dunfield (dot) Firmware development services & tools: www.dunfield.com
com Vintage computing equipment collector.
http://www.parse.com/~ddunfield/museum/index.html
SMPS are always a pain to troubleshoot, and I've always opted to find a
replacement. In this case that isn't probably feasible so ---
They are a pain to troubleshoot, but they're also a part of the classic
computer, and thus should be repaired and preserved. Why do people seem
to think that 'classic computer' == 'CPU only'? I'd
buckshot the components in the switch driver, such as the IC. Sounds
In a supply of this age, I would not be suprised if the chopper driver
was discrete transsitors. 
30 May
30 May
12:33 p.m.
I'd buckshot the components in the switch driver,
such as the IC. Sounds
In a supply of this age, I would not be suprised if the chopper driver
was discrete transsitors.
Anyway - I found the problem - It was a shorted capacitor on the primary side
Well done!
of the transformer - what threw me off was it was NOT
one of the electrolytics...
There's another one beside it which is just like it, so I think I will replace
both.
Maybe part of the snubber network on the primary of the chopper
transformer. In which case, check the associated diodes too.
Supply works fine now - and so does the entire machine.
(Joy at getting an old Apple clone working somewhat overshadowed by the fact
that I finally found a Kaypro today!)
I really must find a CP/M luggable sometime....
-tony
6:13 p.m.
speaking of kaypros I may have a couple available shortly, they are in my
garage and I need to see which ones work and are complete I'm probably
keeping one of them.
At 05:33 PM 5/30/2004, you wrote:
What, not even a TL431 in the secondary-side regulator? That does suprise me.
>>
I'd buckshot the components in the switch driver, such as the
IC. Sounds
In a supply of this age, I would not be suprised if the chopper driver
was discrete transsitors.
It is - the only IC is the Opto-isolator.
Anyway - I found the problem - It was a shorted capacitor on the
primary side
Well done!
of the transformer - what threw me off was it was
NOT one of the
electrolytics...
There's another one beside it which is just
like it, so I think I will
replace
both.
Maybe part of the snubber network on the primary of the chopper
transformer. In which case, check the associated diodes too.
Supply works fine now - and so does the entire machine.
(Joy at getting an old Apple clone working somewhat overshadowed by the
fact
that I finally found a Kaypro today!)
I really must find a CP/M luggable sometime....
-tony
7511
days inactive
7512
days old
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