Peavey pv2000 power amp

[e_c_mccollum]

Anyone know why DDT can come on prematurely?

Right now I have channel B active. Channel A has been removed so it can be repaired (blown output, triac).

The amp was very dirty when I got it and it was also reported it had been dropped. I cleaned up channel B and repaired soldering defects.

The power supply to the amp is good.

The outputs and drivers on channel B are good.

Channel B circuit board is in good condition.

The speakers are good.

I wish I had an ocilloscope. I need to get one soon.

 

[Netlist]

One thing you need to check for sure is that all TO3' are firmly tightened. (Well, not too tight of course )
I'm not sure what you mean with "Right now I have channel B active.". Does that channel work normal or is DDT active on that channel?
Do you have the schematic?

/Hugo

 

[e_c_mccollum]

I have a schematic. I get them free from Peavey.

Since it was dropped I tested the board by gently pushing on it. The amp did go off and on intermittenly. Now I need to remove it and find the cracks in the traces (intermittent area next to DDT chip). This should take care of the DDT problem. It sounds like the preamps cannot cleanly push the drivers.

 

[unclejed613]

be glad it has separate boards. i have a newer pv amp on the bench at work, with a broken connection somewhere. IIRC, it's a 2600, and has one large board with the left and right heatsink tunnels mounted on the board. it's gonna be a pain in the neck to get apart. problem is oscillation in channel A that goes away when you hit the heatsink tunnel with a screwdriver handle, then the relay kicks on and it works fine, until you hit the heatsink again.

 

[d3imlay]

bproblem is oscillation in channel A that goes away when you hit the heatsink tunnel with a screwdriver handle, then the relay kicks on and it works fine, until you hit the heatsink again.

I had an open output R/C network on an amp oscillate once. I've also seen a Hafler amp oscillate because the 100 mfd decoupling cap opened up. Although I've not experienced it, I've heard of oscillations due to thermal insulator issues on output xistors.

 

[unclejed613]

actually it wwas a gps-3500. the schematic was for a gps-2600/3500. i actually found 2 problems... one of those thermalloy butterfly heatsinks on a to-92 transistor had fallen down and was touching the leads.... and bad solder on that channel. fixed both and amp was fine. some moron mech engineer must have thought "this amp will never break", because 90% of this 3 hour job was disassembly and reassembly. i hate it when a simple repair turns into a mech nightmare of "chinese puzzles" and pounds of screws. now on the bench i have a ADJ V-5000 amp, that is a "backwards" design.... where the output transistor collectors are grounded, and the speaker is connected to the power supply common.....all of this, why???... just to be different.....

 

[lolo520210]

I have a Peavey pv2000 power amp, When I play my speakers, the sound leaves for a while like 5 minutes the nit comes up back. What can it be?? Is it because i only use one side or what? I do not have both speakers on, not necessary for me to listen to both. It still happens. Any Help??