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computerpulse
07-05-2006, 06:11 AM
Looking for a power supply board for the cr-2020 or can someone send me a schematic and provide some assistance to bring this thing back up? I rebuilt the capacitance board and now have 128vdc on -b and don't think it's suppossed to be there. Looking for a clean schematic that is readable and wiring diagram or pictures of a properly wired capacitance board. I may have the wires crossed. Currently unit powers up and lights up but thats about it. FM Tuning Meter is pulled to the left and no audio out. I know it's the power supply. I feel if I get this thing correct then everything should work again. Any assistance would be greatly appreciated. Thanks
merrylander
07-05-2006, 06:28 AM
When the FM meter pulls to the left it usually means that the + and - 25 volt supply is hosed. This is usually caused by two things; the 22 ohm fusistors have changed value or gone open, or the 2SD234 transistors on the relay board are open. Things you need to do: change the 22 ohm fusistors to 22 ohm 3 watt Ohmite resistors and change the two 33 ohm 2 watt resistors that are in series with them to 33 ohm 3 watt Ohmite resistors. Then change the two 2SD234 regulator transistors to 2SD525 transistors and when you do use the mica insulators otherwise the heat sinks are live. This was OK when they were glued to the board but now they will be looser. The traces tend to burn away on the power board due to overheating when these modifications have been delayed too long but can usually be surface wired with no great effort, so the last thing you need to do is PM me your email address so I can scan that part of the schematic and PDF it for you.

Rob
ToTo Man
07-05-2006, 06:44 AM
Amazing Rob, - you put that word for word as you instructed me last year :thmbsp:.
You must be getting fed up with these sick 2020's by now, no? :D
ToTo Man
07-05-2006, 06:45 AM
BTW - Computerpulse - you certainly won't regret fixin' her up!.....
merrylander
07-05-2006, 01:09 PM
Amazing Rob, - you put that word for word as you instructed me last year :thmbsp:.
You must be getting fed up with these sick 2020's by now, no? :D

Nope, there is one on the bench right now, rebuilt the power switch and aligned her, set the idle, waiting to see if the owner wants the service mods as the 25 volt supply is currently working.

Rob