Peavey KB60 acting up

[Frank Simpson]

Hi all! I'm new here, and really don't know ANYTHING about servicing amps, but am having troubles with my 1995ish Peavey KB60. I did a search here and did not find a similar problem, and I would be grateful for any insights.

I am the original owner of the amp, and a couple of years after I got it it started acting a bit wonky. If I plug in my synth and power it up, I can barely hear any sound coming through. If I turn the gain all the way up it is very quiet. If I'm lucky, all of a sudden it will jump to full volume (scaring the $*%@ out of me, incidentally) and then it works OK. Other days it will simply not come up at all, and I end up having to play through a d-box which I hate.

Does anyone have any insight as to how I might fix this? I have a gig coming up on Thursday, and would love to be able to use my amp.

Thanks for your time and attention!

[Robert M. Martinelli]

Hi,
It could be you have one or more bad solder joints inside your amp ( input jack ? ). Next time the problem occurs, try to whack the amp with your fist and see what happens.

Hope this helps

Best regards

Bob

OOOOOpssss... I just realized I missed to welcome you....my apologies and a heart-felt welcome to the "place"!

[oc disorder]

Hi Frank and welcome to the forum.
There is a simple fault that is common to a lot of equipment where there is a patch point for inserting effects in-between the pre-amp and the power amp.
Most modern amps have a send and return for this but in your case (correct me if I'm wrong) you have a single jack for this.
It uses the tip and ring and sleeve connections (same as a stereo headphone plug) but in this case the tip has the pre-amp signal and the ring is the input into the power amplifier section.
When not in use there is a small contact that connects the two together allowing the signal to pass through.
What happens over a period of time is the contact can get dirty or oxidize
sometimes a bit of grit can get in there and so no signal can get through.
Sometimes just the action of putting a plug in (tip and sleeve or mono is fine)
will clear "the blockage" other times a contact cleaner such as Caig Deoxit
will clear it.
A test to see if the power amp is ok is to partially insert your synth into that socket so that the tip of your synth lead connects with the ring or amp in connection.If that is clear although it will be quiet as there is no pre amp stage to boost the signal, it shows the power amp is ok.

Another point where the same thing can happen is the headphone outlet which disconnects the speaker when a jack is inserted.
Plugging a pair of headphones in when the amp seems quiet will show if the full signal is at the headphones.
Like the patch point pushing a jack in and out may clear it or you may have to bring in the big guns ie Craig Deoxit.

If they are not the problem its also possible that there are some cracked solder joints particularly on the input jack and also the 2 mentioned above.
If the nut has ever come loose on the input jack the jack could have worked loose on the PC board it is mounted on.
This entails removing all the knobs and nuts from the front panel and the
other fixing screws that hold down the printed board so it can be removed and flipped over to be resoldered.

Well the above is the entry point simple stuff..... post back your findings
and someone may be able to help you further.

[Frank Simpson]

Many thanks for the warm welcome and tips thus far!

I am led to believe it is not an input jack issue, as each of the two channels has a low-gain and a high-gain jack, and all four of them exhibit the same properties.

I did try thumping it with my fist, but this thing is built like a tank, and all I got for my effort was a throbbing fist! I did try lightly bouncing the amp on the floor to see if anything would "shake loose" and once again, to no effect.

There are separate pre-amp ins and outs, and I have tried plugging things into them in an effort to "clear" them, if need be, and there has been no change.

If I plug something into the headphone jack it does cut the speaker completely, and upon unplugging it, it returns to the same quiet condition as before.

All knobs, and input-jack nuts are as secure as the day I bought the amp, and have never shown any sign of working loose.

I really do appreciate your thoughts and efforts!

[ricach]

In line with what ocd suggested, plug your keyboard into the Power Amp In jack on the front. Do you have a decent (but low) signal? Take a cable and patch the Preamp Out to the Power Amp In jack. (This will bypass both contact points on each jack that ocd referred to) Any difference? Plug headphones into the headphones jack - you should hear good volume through the headphones.