Yamaha CR2020 schematic

[grateful]

Looking for service info. Power supply board is the area in question. Thanks in advance.

[riverrat]

Have you checked the database of Yamaha literature that a couple of AKers have been working hard on? I didn't check, but I'll bet they have what you need:

Yamaha literature thread and database (http://www.audiokarma.org/forums/showthread.php?t=154865)

[avionic]

Have you checked the database of Yamaha literature that a couple of AKers have been working hard on? I didn't check, but I'll bet they have what you need:

Yamaha literature thread and database (http://www.audiokarma.org/forums/showthread.php?t=154865)
NOT!!

[Njord Noatun]

NOT!!Yes and no: Yamaha often published schematics as part of their owner's manuals: The CR-2020 owner's manual is in the DB and the schematic is part of it. However, the scan is from Yamaha Japan's web site and the quality of the scan leaves a bit to be desired: So if the scan is sufficiently legible for you to use it for your job at hand is a different matter altogether and only the user can determine that.

[merrylander]

If you mean the vertical power supply board with big coke can caps apart from the filter cap values it is identical to the CR-1020 and that schematic is on hifiengine.com. That is the subject of the service bulletins that recommend changing the 22 ohm fusistors to 22 ohm 3 watt resistors and changing the 33 ohm 2 watt resistors to 33 ohm 3 watt resistors. It also recommends replacing the two voltage regulators (2SD234) on the relay board to 2SD525.

[grateful]

Thanks Merrylander I do have those bulletins and will do as described. I suspect those procedures will fix this one also. I would like to measure and verify the missing regulated voltage when failing to verify this is the problem. The unit is intermittant the amps are fine no DC offset. When it shuts down the tuning meter is driven to the left and the tuner and preamp section become inoperative. Btw I have sent you a check for the ribbon cable for the px2. Please let me know when you get it. Thanks everyone for the database tips I will check them out.

[merrylander]

If the tuning meter indicates -50 then the mods are exactly what you need because that is a symptom of the + and - 25V dropping out. Don't forget to install the jumper to bridge the power switch.

[grateful]

Bridge the power switch? Do you mean double up the contacts? Is there an unused pair?

Regards Dave