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StompinSteve · 07 February 2023, 15:53

Back to my Powersupply. Salocinx (my

repair shop) here in Switzerland, who chimed in a few posts above, has hooked up his Digital oscilloscope to the Tick Signal. Not only is the signal doing the mamba (fluffing about between 141 and 149.9Hz at the moment), the signal is also of pretty poor quality. Not a nice steady pattern at al.

He suspects Varistor RV21. There are (many) A3000 110V PSU's out there where RV21 is not rated for voltages above 120V (with some margin above). He will open up my PSU soon to see inside. If his suspicion is correct, that could be cause of the trouble.

Salocinx is not the only one mentioning this. Anthony Hoffman from New Zealand recommends changing this varistor as well.
Source: http://amiga.serveftp.net/A3000_HardwareGuide/psu.html

Mr. Hoffman has been the only person to ever mention this. All the others that i've found never spoke a word about a varistor being changed. I was hoping that, because my PSU was produced relatively late in the A3000's lifecycle, the only difference would be the "110V bridge-wire". On the other hand, if Commodore could save a few pennies by using a cheaper, less capable varistor in 110V PSU's, that would not suprise me at all either...

Obviously, someone going from 230V to 110V does not need to worry. Only those who are going the other way (like me) might run into this.

Anyway, my PSU will get completely rebuilt. Out with the old, in with new, fresh components. I just don't trust that PSU anymore and now that it has it's guts hanging out, might as wel replace everything to put my mind at ease.

07 February 2023, 15:53	#17
StompinSteve Village idiot Join Date: Jun 2021 Location: Switzerland Posts: 267	Back to my Powersupply. Salocinx (my repair shop) here in Switzerland, who chimed in a few posts above, has hooked up his Digital oscilloscope to the Tick Signal. Not only is the signal doing the mamba (fluffing about between 141 and 149.9Hz at the moment), the signal is also of pretty poor quality. Not a nice steady pattern at al. He suspects Varistor RV21. There are (many) A3000 110V PSU's out there where RV21 is not rated for voltages above 120V (with some margin above). He will open up my PSU soon to see inside. If his suspicion is correct, that could be cause of the trouble. Salocinx is not the only one mentioning this. Anthony Hoffman from New Zealand recommends changing this varistor as well. Source: http://amiga.serveftp.net/A3000_HardwareGuide/psu.html Mr. Hoffman has been the only person to ever mention this. All the others that i've found never spoke a word about a varistor being changed. I was hoping that, because my PSU was produced relatively late in the A3000's lifecycle, the only difference would be the "110V bridge-wire". On the other hand, if Commodore could save a few pennies by using a cheaper, less capable varistor in 110V PSU's, that would not suprise me at all either... Obviously, someone going from 230V to 110V does not need to worry. Only those who are going the other way (like me) might run into this. Anyway, my PSU will get completely rebuilt. Out with the old, in with new, fresh components. I just don't trust that PSU anymore and now that it has it's guts hanging out, might as wel replace everything to put my mind at ease. Last edited by StompinSteve; 07 February 2023 at 17:10.