Almost identical power supply in Motorola set-tops! I have fixed about a dozen of those by replacing the one capacitor used to power up the UC3844, so it’s really interesting that the diode failed in this one!
I have asked on the Facebook forum, but maybe you would like to do it. What is your procedure for diagnosing PSUs? if for example it has failed. NOTHING that requires a scope.. we want to get it working! we hope the caps will bring it up better.. this is not about performance.. its about repair. ST PSUs like the ASP34 or SR98. Do you test in a way that you can determine if its something more serious or not fixable? Almost everyone re-caps and if its working then great.. should be better with new caps - but if it has failed, then knowing if its worth fixing would be fantastic! Having this on a RU-vid video would really help the hobby.
It's good to have found the culprit in the PSU, but where is the maintenance of the capacitors in it ? Those are not made to be used above 10 years of use, and this machine is 30 years on average...... A machine cannot be considered maintained or service without those being replaced by new ones.
Where is the maintenance? Off-Camera. This video is focusing on the repair, finding what the issue is. It was an early video on my channel, and the main purpose was to show a friend of mine. I do a lot of maintenance and service, although recap is recommended especially for PSU, recap is not always the answer (I have never seen primary filter caps fail for ex, always secondary of the SMPS).
@@AnalogThinker Doing the repair is ok, but doing the servicing as well. Recap is not only recommanded, it has to be done. The regulation in Atari computer is crap, this can be seen with an oscilloscope. This for a few reasons : Atari has used 3rd grade taiwanese capacitors (very bad ones). Once replaced, this is doing lots of good to them. The capacitors used were not made to last 30 years (never!), and they currently show bad results when tested.
