Peavey Musician Mark 3 gut shots?

[brianjdc]

Hi Guys,

I got a used Musician a few months ago that I've been loving untill today. My band mate dropped his bass drum pedal on top of it. now it powers on with no sound. no hum just dead silent. I took it apart and looked around. I noticed a problem withthe c36, c37, c40, c41 cluster. Some leads are poped off with solder globs on the ends. So could someone please hook me up with a gut shot of that section if you could so I can solder the leads back in place?

Please and thank you!

Brian

[Fragger]

I have in my possession an old working Peavey Musician. Mine isn`t a Mark III and not the same as yours; it may or may not be similar. Post pictures of the effected area, I`ll open mine and post pictures if they are relevant to yours.

[brianjdc]

I appreciate any help you can give. I'm thinking the bump knocked some leads loose on the cap. In the 2nd pic you can see the one cap isnt hooked up to anything.

[Fragger]

Someone has been in there messing and added caps and then disconnected?

Read through this thread: http://music-electronics-forum.com/t26534/

Download the schemo provided by the most excellent, Jazz P Bass.

Page 4 of the pdf file shows the capacitors you spoke of, compare connections to yours.



Will try to make time later and look at my Musician.

[brianjdc]

I'm going to try disconnecting the brown caps to return it to what the scheme shows. Those had to of been in there for atleast 10 years, thats when I bought it. any idea why someone would piggy back those caps? I'd really appreciate it if you could take a gander in yours when you get a second.

[brianjdc]

I disconnected the extra caps. still nothing. the way they were wired, they were bridged between the negative legs of c36/37 and the positives of c36/37. I tested the preamp. that is working just fine. Seems to be a power amp issue

[Jazz P Bass]

Yeah someone did not have axial caps, so they used what they had. Radial.
Those caps are for the prevoltage on the +15 & -15V regulators.
If the originals are bad they may pull down the voltage going into the regulators by not filtering out the diode ripple.
A quick check with a volt meter set to read Vac will verify if they are good or not.
Here is the schematic: http://music-electronics-forum.com/a...29-markiii.pdf

[Enzo]

It may not look like it, but the brown caps are simply in parallel with the blue ones. Those old caps are in a split supply, so the negative end of one is grounded while teh positive end of the other is grounded. SO by soldering a new cap to the two negative ends Connects it to the ground at one end and the V- at the other. Same sort of deal at the two positives end.


I would wager someone had some hum issues and decided adding a couple 2200uf capsw would help. And there they are. Looking at the photos, ther is only one place any of them could be wired. In the top picture, the leg in the air goes down to the blob of solder not doing anything. In the lower photo, the two wires are soldered to the blobs of solder right near each one.

But those caps were never going to be the problem. If they were shorted, you'd blow fuses, if they were open, at worst you'd have hum.

Let us be systematic. Pull the speaker cable plug out of the back of the amp, leave the other end still plugged into the speaker cab. Touch the tip of the plug to a terminal on a 9v battery and hold it there. Now lower the shaft of the plug down to touch the other battery terminal. A working speaker will pop or thump with each touch. Does yours?

Assuming the speaker works, check the wires from the speaker jack on the amp panel back to the white connector plugged onto the power amp board. The connector in the lower right of the top photo. Tight?

With the amp boards in place, speaker connected, power on, there is ABSOLUTELY no sound? NO background hum or anything? How about any thump at turn on or turn off? Frankly that would be unusual.

At the far end of the board from all those caps is a four wire connector for the cable to the preamp (the front panel.). Pull thatr connector off and power up, speaker connected. We now have the power amp running alone. There are four pins for that connector. One, then a space, then three more. Of those three, the one closest to the corner is the input pin - the input to the power amp. Touch it with your finger. Get hum?

[brianjdc]

I'll post results tonight. Thanks Enzo and jazz p for hoping in with advice!

[brianjdc]

ok here's what I have so far. It's not the speaker cab, I hooked a different head up and it worked fine. I reseated all the connectors. I pulled the connector from the pre and tried touching the pin. I didnt get any hum. It's dead silent no pops or thumps when powering up. I think there may be an issue witht he speaker output jacks. I checked for continuity between the speaker jack solder lugs and the pin connector where it attaches to the board and every thing light up with my testor. Now when I pluged an audio cable into the output jack and checked between the cable and the connector the only time I got continuity was with the sleeve. The tip didnt show a completed circuit from the tip of the cable to the connector or the solder lug on the jack. I'm going to take a better look at it tomorrow. But they would certainly explain why I'm not getting any sound. Makes sense right? Or am I missing something? Thanks

[brianjdc]

re checked all the wires from the output jacks, everything looks good now, still getting dead silence. any suggestions what to check next?

[Enzo]

Right next to your pile of caps, see that ugly brown cardboard-looking thing? It is a series inductor in the amp output, it connects to the speaker wire plug. Pull up on it to see if one end is broken free. Also check the solder under it.

If that seems OK, plug a cord into the speaker jack. Power off. Meter on resistance. Measure from the free end of the cord at the tip, to either end of that inductor. There needs to be continuity, is there?

Oh, and the speaker jacks, the output of both jacks runs through the cutout contacts of the 4 ohm jack. Make sure those contacts are making and clean.

[52 Bill]

Do you have a volt meter? Have you actually tested any of the voltages on the power supply or in the power amp?

[brianjdc]

ok I think i've got it narrowed down the the 4 ohm output jack. Any idea where I can get a replacement for it I've never seen a 4 condutor 1/4 jack before. Whats the proper name for it?

thanks

[Enzo]

Try cleaning it? Use a matchbook cover or a business card of something, even a dollar bill. For the outside contact, slide the paper in there and plug a plug into the jack to pinch the paper in the contacts. Pull it back and forth a little to buff the contacts. Then pull the paper out and put it in the inner contact space. Pull out the plug so the paper is now pinched between those contacts, and rub them clean.

ANy help?

It is a Switchcraft with a make/break set of contacts on the tip. I think it is a 13A, but check with PV parts, they may still have them.