peavey xr600c weak reverb

[clinkous]

Any suggestions to diagnose weak reverb? Has slight reverb on all channels with both channel and master reverb controls maxed. Reverb rolls back with the master, just very weak overall. Have owned since new but was stored for years.

Replaced some pots and cleaned connections and otherwise works fine.

Any ideas would be greatly appreciated!

Thanks

[TomCarlos]

Is the reverb weak on all channels or just one or two?

I would start by checking the rca connectors going to the reverb tank. Get yourself a spray cleaner like DeoxIT D5 and spray the connectors on the cable and make sure the rca connectors on the tank are clean. You can (carefully) use the cleaner there too.

You should undo the tank from the case and inspect it to make sure there are no dangling connections from the rca connectors to the transducers. Take a photo and post if you can.

I have worked on a few of these PA heads. I typically use the DeoxIT F5 on all the pots, as they get dirty over time. You can tell if you try to turn the knobs and feel some resistance. The pots should turn easily.

Try this first. If you still have a problem, I am sure others will chime in with troubleshooting the circuit.

[Chuck H]

Here's a schematic to keep us all on the same track. Click on the image to open in it's own window. Then click on it in the new window to expand it.

[Chuck H]

Start by giving the amp a whack to see if the reverb crash is at seemingly normal level. That's a decent way to tell if the recovery stage and reverb output are functioning ok. If they are, check the output of U16A first to see that the reverb is actually being driven.

[Leo_Gnardo]

Here's another possibility - has the reverb tank ever been changed out in this unit? Reason I'm asking is tank inputs come in a variety of impedances & if you have the wrong one, reverb will be weak. You can measure the DC resistance of the tank's interior transducers easily enough by pulling off the RCA plugs, measure the resistance by putting one meter lead in the jack and the other on the exterior part of the RCA jack. You should read somewhere between 30 and 80 ohms on the input side. All of 'em read about 200 ohms on the output.

If you read about 1 ohm on the input side, the tank is meant to be driven by a tube/transformer circuit commonly found in guitar amps, and can't be properly driven by your transistor/op-amp circuit.

Should take a couple minutes at most, it's worth a check.

[Enzo]

Agree^^^
The correct reverb pan in there should be a 4EB2C1B or an 8EB2C1B. Look printed n the pan. If you have instead some other letter than E in the second position, it is wrong. Also it is possible the thing has the two cable plugged into the wrong jacks. See if reversing them helps.

[Jazz P Bass]

Stored for years?

Check for insect residue in the tank.

Clean & lube the tank connectors real good.

[clinkous]

Thank you all for the suggestions. At work but will check for reverb when bumping the tank when i get home. I'll also check the tank itself and clean cable connections.

In reply, the problem is in all channels and the tank hasn't been changed. I don't believe the connector has ever been disconnected from the tank side.

I'll do these checks and report back this evening.

Thanks again.

[clinkous]

I'm pretty sure that the loose spring laying in the bottom of the amp under the reverb pan MIGHT be the cause of my weak reverb. The wire is broken from the end of one of the springs.

Thanks for all of your help. I do have a twin reverb tank and if any one knows off the bat if this is doable or not I'd appreciate a response. Otherwise I'll just run my quadraverb for effects. In the future I will procure another tank because this head is worth keeping.

Thanks again!
Chris

[clinkous]

Answered my own question about using guitar amp reverb tank by re-reading thread. Sorry about that!

[NoelJB]

Kinda sounds like the drive to the reverb tank is weak.