Yamaha sw500

[ca7922303]

Can you tell me where relay coil pins ar? Thanks.

[vintagekiki]

Look at the schematic Yamaha sw500

.

[Jazz P Bass]

Look up the part # of the relay and download the datasheet.

[The Dude]

Also note that the relay coil has a diode across it. That's usually the easiest way to find a relay coil.

[ca7922303]

Found RY201(relay), have to resolder 12 transistor legs to board, then will test for voltage @ relay asap. Thanks for the help.

[g1]

Found RY201(relay),

If you look on pg.17 of the service manual, you can see that D233 is directly across the relay coil. That is the diode The Dude referred to in post #49. That may be a more convenient spot to check for the relay voltage, depending on which side of the board you have access to.
You will want to monitor the DC voltage there from start-up. It should measure 0V at turn on, then after a couple seconds it should go to approx. 24VDC.
If that is what happens, then the amp has come out of protect, and the power amp area is probably ok.

[The Dude]

There is also the possibility that even though the relay clicks, internal switch contacts have been arcing and are no longer making contact. I would also check continuity on the switch contacts of the relay.

Edit: After power up, put your ear right next to the speaker. Can you hear any noise at all- like maybe a very slight white noise. If you hear SOMETHING out of the speaker, it indicates the relay is working and the amp is out of protect.

[ca7922303]

About to solder transistors back in, continuity test only shows a reading on two(2) of six(6) pins. 1072 & 538 on same pins reversing leads. No reading on other four(4).

[ca7922303]

Transistors soldered back in, all six(6) pins on ry201 read 000-025-000 on 2000mv scale.

[ca7922303]

What do you make of the last readings I got off of relay?

[Jazz P Bass]

Not to be abusive but your posts seem to be lacking in any technical information.

[ca7922303]

Was referring to previous post #54.

[vintagekiki]

Not to be abusive but your posts seem to be lacking in any technical information.

There is only good wil ...

[g1]

Please answer the question from post #52.

[vintagekiki]

There is also the possibility that even though the relay clicks, internal switch contacts have been arcing and are no longer making contact. I would also check continuity on the switch contacts of the relay.

It happens over time that some relay contacts lose elasticity, or on switch contact due to the arc platinum oxidizes, so even though the relay "works" but no continuity is established.