Yamaha sw500

[nickb]

Speaker has been replaced, I was just stating that existing speaker had maybe been damaged by amp. I only have the amp to test. Enclosure w/speaker is elsewhere.

Has the faulty amp been connected to the new speaker? If so, and the amp is outputting DC, the new speaker may now be damaged.

[ca7922303]

Not connected to new speaker. Can I get help in how/where to test outputs? Do I get readings for all 3-4 legs on 13 transistors that lay down outside the board! Photos attached.

[Jazz P Bass]

"Do I get readings for all 3-4 legs on 13 transistors"

Before you check the transistors, check to see if you have any DC volts on the output.

BTW:the '4 legged' component is most probably the bridge rectifier.

[g1]

Can I get help in how/where to test outputs?

Not quite sure what you are asking, but to check for DC at the output, put one meter probe at each of the terminals that would go to the speaker.

[ca7922303]

Believe this 4 pin is the speaker connection. Don't have the new speaker and enclosure with me right now, only the amp. Which of the 4 pins and what reading at what setting am I looking for? Thanks.

[ca7922303]

2 pin #cn209 reads 10.8 v on 200mv scale. 4 pin #cn203 reads 8 & 14.6 v depending on which pin ground lead is on.

[ca7922303]

Reading thru external main output getting no more than 3.4 v on 200mv range.

[Helmholtz]

2 pin #cn209 reads 10.8 v on 200mv scale. 4 pin #cn203 reads 8 & 14.6 v depending on which pin ground lead is on.

You should learn to read your meter. It is impossible to get a 10.8V reading on a 200mV scale.

[ca7922303]

Reading thru high pass external output (100hz + 4db) is no more than 3.6 on 200mv range.

[ca7922303]

Should I have said 10.8 mv?

[ca7922303]

I have a PC based oscilliscope and a signal generator. Any suggestions?

[Helmholtz]

Should I have said 10.8 mv?

Yes, in a mV range any displayed number means mV. So if you see 10.8 in the 200mV range , it means 10.8mV or 0.0108V. That's close to nothing.

[ca7922303]

Anything stand out in the readings I'm coming up with?

[Jazz P Bass]

What exactly is the problem.
You basically have NO Vdc on the hypass output.
What you infered in the beginning of the post was that the main speaker was blown.
So....
What is the Vdc on the Main output.
I really feel that we are going in circles here.

[ca7922303]

I don't know if the amp blew the speaker. All I can tell you is when it was given to me the speaker was bad and the amp had no sound, but did power on .It was more like a question I in the beginning wondering if the amp was the reason the speaker was bad?