Wharfdale pm700 pa schematic?

[nosaj]

I have a Wharfdale PM700 pa that has no output through the preamp section. Output works fine. Any chance anyone has a schematic buried somewhere as Wharfdale is unresponsive.

Thanks,
Jason

[Roly]

This?





The pros: so many things are brought out that it's fairly easy to localise the problem, as you seem to have worked out.

Con: this style of build is often a real cow to work on - hope you get lucky with the mechanics.

[nosaj]

YES!!!  that is it.
Do you have this in a pdf form? When I d/l the image the info is too blurry.

Thanks,
Jason

[J M Fahey]

I think that's a Yamaha PM700 schematic.

Although the Wharfedale might be an "unofficial clone"

FWIW:
https://www.gearslutz.com/board/attachments/low-end-theory/214353d1295024267-yamaha-pm700-direct-outs-pm700-newschematic.pdf

[g1]

 I don't think it will be like the Yamaha:

[DrGonz78]

Here it is...

Edit: This is all I could find and now I realize the resolution on it is less than ideal. Perhaps it will help, but hard to read. Sorry.

[DrGonz78]

Okay go to this link and read post #7 in this thread on MEF...

http://music-electronics-forum.com/t35362/

Apparently running that Sumatra PDF reader program allows the values to be read better, if nothing else. I am running linux so I will see how this works running WINE.

Edit: Yup this Sumatra PDF reader does help a tad bit. It is still hard to read but at least you'll have a chance, good luck!

[Roly]

I think that's a Yamaha PM700 schematic.

Although the Wharfedale might be an "unofficial clone"

FWIW:
https://www.gearslutz.com/board/attachments/low-end-theory/214353d1295024267-yamaha-pm700-direct-outs-pm700-newschematic.pdf

   {Why don't they put on bloody TITLE BLOCKS FFS?  Shoulda spotted the Yamaha drafting style, obvious now}

That PDF only contains some blow-ups of the input stages, that's all, not the post amps to the right.

I guess nosaj will just have to resort to a microscope and good old-fashioned tech-nishing then.   

[g1]

Doc, is that the service manual from elektrotanya ?

[DrGonz78]

Doc, is that the service manual from elektrotanya ?

That's the one... For better or for, in this case, worse.

[Roly]

nosaj

Are you still with us?

What is the nature of the problem?

How are you getting on with it?

[nosaj]

I now have signal passing through the preamp channels 1-5 now, very low output though ( like putting my ear to the speaker low).  Master volume makes no difference  when rotated. So I used a pair of headphones and probed the master volume with 1k sine going in ch 5. I get sine on one leg, then move to the other leg of pot hear no sound until I get  to like 9 or 10 on switch.  part number is 503A  50k pot. Going to sub another in and see how it goes.

jason

[Roly]

That is more likely to be an artifact of using lowish impedance headphones to trace a highish impedance circuit.  I'll bet the impedance of your 'phones is a lot lower than the resistance of that pot, and that's how I would expect it to behave, however...


Test it with your multimeter.

Take it out of circuit if needs be.

That may not be the actual problem, so confirm that it's o/c at the top before chasing/replacing parts.


You would be better off using some active computer speakers for this signal tracing.

[nosaj]

Ok computer speakers with probe confirm pot is operating correctly.   So after master vol it would go to the limiters(clippers)?

If pics would help tell me which ones would be helpful.

Thanks,
Jason

[Roly]

{Finding a readable circuit would be helpful.    }


I downloaded the Warfedale PM-700 Users Manual for a closer look at the front panel.

a) Take a known good lead and plug it into "Main Out" and "Power In" (bottom right on panel) and test.

b) Are you getting normal signals at "Record Out"?  "Effects Send"?  (With their controls up)

Report results.