Peavey 2.6C Question

[jmaf]

Your board is charred under R141 and R142. Those are good quality resistors, but maybe you oughta split the load into 3x 240 OHM 3 Watt resistors in series instead of one 5 Watts. It won't look as good on the board, but will work better.

[Enzo]

Or mount to the chassis, a couple of those aluminum 25 watt resistors with mounting screw holes, and run wires back to the board.

Those resistors are dropping from HV to the 15v zeners, and it is normal to run pretty hot.

[BowerR64]

The three resistors between the main filter caps? See the two silver diodes, one above and one to the left? Those are 15v zener diodes, and when one shorts out, it will burn up its resistor. That is what those resistors do.

I can't read it from the photo, but there is print in the foil pattern lower left corner. I can see PV2.6C but is there any indication of a revision level? Or mention of a year? Gather up all the numbers and stuff from that legend down there, and contact Gene Ford at the factory. Ask him if there are other revisions that are documented.

And just in the name of science, ask him if they can service the board if sent by itself.

Oh never mind, here, you have the first cut of the board.

So if the 3 resistors between the main filter caps have chared the board the silver zenors are bad?

I have one that still functions but about about 20 minutes or so it gets hot and trips the front DDT led on the front. it still works though so we quit using it and i decided to try and find why it was overheating before it nukes iself.

[Enzo]

Quite likely it needs the bias to be tweaked. in many cases in PV power amps, this will not be an adjustment, but rather a diode choice.

I have no idea what parts are where, it has been five years since this discussion. But resistors that drop voltage to zeners often run hot, and discoloration of the

[BowerR64]

Quite likely it needs the bias to be tweaked. in many cases in PV power amps, this will not be an adjustment, but rather a diode choice.

I have no idea what parts are where, it has been five years since this discussion. But resistors that drop voltage to zeners often run hot, and discoloration of the

Well when doing a search for this amp this is about the only results that come back so i had nothing to lose because there was no other discussion about this amp any where else.

I bought 2 power amps off local craigslist one for me one for my friend. Both Peavey, one is the PV2.6c the other is a PV260 when you peek in at the resistors on the 260 they are up off the board. Maybe its the newer redesigned unit of the 2.6C?

I thought about just ordering the 3 resistors and putting them in above the board like the 260 and see if that helps keep them cooler and maybe doesnt trip the DDT on the one channel. While its on i felt all the fets and they were all cold the only heat when its on is the 3 resistors in the front.

What i dont understand is why only the "B" channel DDT led comes on? the "A" channel stays off.

I tried to download the schematic from this post but i cant get it to even open.

[Enzo]

That is because it was put there before our famous server crash. That left us with a lot of file names on empty files. Contact customer service at Peavey and ask for the drawings.

Or here:

http://bmamps.com/Schematics/Peavey/...ice_Manual.pdf

Why does one light come on and not the other? First make sure the amp is not switched to BRIDGE mode on the rear panel. Otherwise, one works different from the other because one channel has the problem. Why does my left arm itch, but not my right? because the left one is the one the mosquito bit.

Resistors get hot because too much current is flowing. It isn't the resistors' fault. DDT is not tripped by hot resistors. It might be tripping because of whatever is overheating the resistors, but cooling them instead of fixing teh problem won;t cure the DDT issue.

[BowerR64]

That is because it was put there before our famous server crash. That left us with a lot of file names on empty files. Contact customer service at Peavey and ask for the drawings.

Or here:

http://bmamps.com/Schematics/Peavey/...ice_Manual.pdf

Why does one light come on and not the other? First make sure the amp is not switched to BRIDGE mode on the rear panel. Otherwise, one works different from the other because one channel has the problem. Why does my left arm itch, but not my right? because the left one is the one the mosquito bit.

Resistors get hot because too much current is flowing. It isn't the resistors' fault. DDT is not tripped by hot resistors. It might be tripping because of whatever is overheating the resistors, but cooling them instead of fixing teh problem won;t cure the DDT issue.

This is the 2.6C you cant bridge this model its the bottom of the line. The 260 isnt bridgeable either.


When i asked why one side trips but not the other, the 3 resistors are for the power filtering arnt they? each channel has its own resistors in the back near the fets. The 3 resistors and the 2 caps dont have anything to do with the power feta do they?

[Enzo]

OK, I didn't look up the owner manual to see if it bridged, that is just an automatic thought when one channel acts different from another.

I don't have the amp to see what three resistors. The only group of three I see on the drawings are R141,142,153, it is those? Actually there is also R152 on the other side of one of the caps, it goes with them. No, those have nothing to do with the output transistors. The two R141, R142 are dropping resistors for the 15v zeners. They do run hot normally. One end of each of those two would have your high voltage on one end, whatever that is in this amp, and then 15v on the remaining end. One for each polarity. Those power supply circuits serve both channels, they have no way to affect one channel different from the other.

The four power resistors associated with the four output transistors on each side are what we call ballast resistors, and they are ther to help the transistors share current equally among themselves, as well as provide a sampling for the current limit circuits.

Just for information, the output transistors are ordinary NPN and PNP bipolar transistors, they are not FETs.

I suggest monitoring the current draw from the two channels and compare, the hot side probably has excessive current, and the cure for that may well be making changes at Cr107, CR110, and CR114. Or CR207, 210, and 214 if the other channel.

[BowerR64]

OK, I didn't look up the owner manual to see if it bridged, that is just an automatic thought when one channel acts different from another.

I don't have the amp to see what three resistors. The only group of three I see on the drawings are R141,142,153, it is those? Actually there is also R152 on the other side of one of the caps, it goes with them. No, those have nothing to do with the output transistors. The two R141, R142 are dropping resistors for the 15v zeners. They do run hot normally. One end of each of those two would have your high voltage on one end, whatever that is in this amp, and then 15v on the remaining end. One for each polarity. Those power supply circuits serve both channels, they have no way to affect one channel different from the other.

The four power resistors associated with the four output transistors on each side are what we call ballast resistors, and they are ther to help the transistors share current equally among themselves, as well as provide a sampling for the current limit circuits.

Just for information, the output transistors are ordinary NPN and PNP bipolar transistors, they are not FETs.

I suggest monitoring the current draw from the two channels and compare, the hot side probably has excessive current, and the cure for that may well be making changes at Cr107, CR110, and CR114. Or CR207, 210, and 214 if the other channel.

Im not good with trouble shooting, the diodes seem to check good, the 2 silver zenors near the 2 larger filter caps. I called em fets because i have a Marshall Mosfet lead 100 and the Power fets in it look simmilar to these being ina metal can not a silicon block with a heatsink fin thing.

You can see these resistors in the images have been hot. Now we did hook both outputs to 2 4ohm speakers one on the A and one on the B channel Maybe it needs to be hooked to 8 or 16 ohm?

Thanks alot for your help, the amp still works but im sure its not long and it will be a paper weight. Where should i check for current draw?

[Jazz P Bass]

The resistors in question are the 'dropping resistors for the + & - 15Vdc supplies.

They do run hot as they are 'dropping' a lot of voltage from the V+ & V- down to where the zeners can regulate the supply to 15 volts.

Test the supply.
Is the + & - 15 volt supply reading that?

I doubt that this is the reason for the amp misbehaving.

Peavey_PV-2 Power Supply.pdf

The amp is rated to run into a 4 ohm load.
100 watts RMS output (@ 0.1% THD) with a 1.0v input signal.

[BowerR64]

The resistors in question are the 'dropping resistors for the + & - 15Vdc supplies.

They do run hot as they are 'dropping' a lot of voltage from the V+ & V- down to where the zeners can regulate the supply to 15 volts.

Test the supply.
Is the + & - 15 volt supply reading that?

I doubt that this is the reason for the amp misbehaving.

[ATTACH]38621[/ATTACH]

The amp is rated to run into a 4 ohm load.
100 watts RMS output (@ 0.1% THD) with a 1.0v input signal.

Where all should i check for voltages? every where that has the + or - 15 volts on the schematic?

im wanting to say i can turn it on and the DDT doesnt kick on for about 20 minutes which is why i thought it was heat related.

What about this, could the resistors be getting so hot that they overheat the zeners after a bit and the zeners break down and its causing the problem? Like the newer one we have the PV260 has the resistors up over the zeners so maybe they are high enough up where they dont overheat the zeners.

Ill have to feel the temps of the PV260 and get some images of it

[52 Bill]

im wanting to say i can turn it on and the DDT doesnt kick on for about 20 minutes which is why i thought it was heat related.

Is something actually getting hot, like the heatsink for the output transistors? Do both side get hot or only the B-channel?

This amp has a single power supply for both channels, if the power supply was failing, both channels would be failing.

[BowerR64]

Is something actually getting hot, like the heatsink for the output transistors? Do both side get hot or only the B-channel?

This amp has a single power supply for both channels, if the power supply was failing, both channels would be failing.

Well thats what i originally thought and thats why i opened it up and from a cold start i plugged it in and none of the Fets or power transistors get hot at all. The only heat are from the 3 sandblock resistors in the front that i have posted pictures of. Nothing else in it is getting hot.

Only the B side trips the DDT but when it trips the LED comes on the amp still works both channels still function and i dont hear any distortion or loss of volume not yet. I havnt let it go much longer past the time the DDT led comes on. I dont want to push my luck

I know sometimes when audio stuff fails it can avalanche one part can fail and when it blows it can take a tone of parts with it. So i thought if its just a few resistors, or an old leaky cap or diodes ide try and catch it now before it turns into a mess.

I got both amps off craigslist for $50. each my friend kept the good one. When i called the guy back on craigslist he claims that the DDT LED must just be faulty it never happened to him and he couldnt explain why its doing it. He said he is an audio engineer.


If i order the 3 resistors to try and just get em up off the board and away from the zeners would it be wise to order 10 watts insted of 5 watts? would 10 watts help it run cooler? or would it just use more power/ amps?

I also could just solder in some solid core wire and then solder the resistors to those wires and get em up off the board before i order the new parts and try that first see if it helps any

[The Dude]

I've seen "similar" with a failing triac. Have you changed the SAC187 yet? A couple of points on the triac.

1) A "down and dirty" trick to check for a failing triac is to set the meter to diode check and meter across the output terminals (of course with amp off). You will see some charging and eventually get to infinite resistance, OL, or whatever your meter says. If you read any resistance or constant voltage drop (diode check) there, it's likely you have a problem at the output and likely a defective triac.

2) If you suspect the triac is bad, you can temporarily remove it and see if the amp works normally. It's there only for DC output protection.

[Jazz P Bass]

Concentrate on the problem.

As Bill stated, both channels use the same power supply.

If the resistors where an issue, both channels would be affected.

The voltages can be checked right on the cement resistors.
One side of either resistor will be +HV/-Hv & the other will be + - 15 Vdc.
(Consult the power supply pdf that I posted.)

The DDT circuit itself may be at fault.
Try to monitor the output pin (#7) of IC U300B.
It should go high when the DDT LED lights.

Peavey_PV-2 DDT.pdf