RB800 Gallien Krueger volume problem.

[filibertin]

Has anyone ever had the problem of volume fluctuation with their Gallien Krueger? Lately when playing the volume decreases and increases on its own. Any suggestions as to the cause and how to fix it?

[WingKL]

Try the ole clean/bypass the effects send and return jack with a patch cable trick.

[B-string]

Yep effects return jack internal contacts are dirty.

[filibertin]

I have the same problem with my RB800 a friend of mine told me it could be the capacitors. ? My amp is 10 years old,I'm thinking to buy a new amp or maybe take it to be repair ( ? $ )
note: I cleaned the contacts all ready and it worked fine for two gigs than go back with the same volume problem.

[B-string]

Originally Posted by filibertin

I have the same problem with my RB800 a friend of mine told me it could be the capacitors. ? My amp is 10 years old,I'm thinking to buy a new amp or maybe take it to be repair ( ? $ )
note: I cleaned the contacts all ready and it worked fine for two gigs than go back with the same volume problem.

Then you probably did not do a through job of cleaning the effects return jack! A tech could do a better job of it for you, probably cheap.
I doubt the caps are bad yet.

[Filthybass]

Could the humm on my gk be capacitors?

[B-string]

Originally Posted by Filthybass

Could the humm on my gk be capacitors?

Yes, as well as a poor ground connection.

[will33]

It's easy to do a thorough cleaning job if you take to top cover off. All the jacks and pots are easily accesible inside there. Get the cleaner on all the jack contacts and spray it in the little hole you see on the side of the pots inside.

Yep, caps and grounding are usual suspects for hum, though I don't think 10 years is quite long enough for normal wear and tear unless you either been playing the thing constantly, like dozens of hours every week, or more likely, it has set not even being powered on for a long time.

Check the grounding/connections, etc. at the input jack too. Possible something is intermittent there if cables been stepped on, amp has fallen off stack or generally been knocked around a lot. Most old 800RB's look like they've been through at least 2 wars and are known for holding up pretty well but everything has it's limits.

[Z-Bass]

Originally Posted by B-string

Yep effects return jack internal contacts are dirty.

Would something like this cause the amp to drop in volume and then cut out. I have a '92 400RB that started doing this recently. Basically while playing, the volume starts to drop and then no sound, amp power is still on. I shut the amp off, wait a few seconds, turn back on; volume is back but when I start playing again, same thing happens. Not getting the fluctuations like the OP indicated on his 800RB.

Note that this only happens at loud rehearsal volumes. With individual practice (low volume) settings, the amp operates fine for long duration.

Could this be a dirty effects loop? Any other thoughts? I am going to have a local tech give it a thorough cleaning/once over but wanted to check to see if I could gather some info before hand.

[B-string]

Originally Posted by Z-Bass

Would something like this cause the amp to drop in volume and then cut out. I have a '92 400RB that started doing this recently. Basically while playing, the volume starts to drop and then no sound, amp power is still on. I shut the amp off, wait a few seconds, turn back on; volume is back but when I start playing again, same thing happens. Not getting the fluctuations like the OP indicated on his 800RB.

Note that this only happens at loud rehearsal volumes. With individual practice (low volume) settings, the amp operates fine for long duration.

Could this be a dirty effects loop? Any other thoughts? I am going to have a local tech give it a thorough cleaning/once over but wanted to check to see if I could gather some info before hand.

It could be. Try an instrument cable to loop the effects jacks. It could also be the idle bias has drifted and under heavy use the output is overheating. When the heat sink temp gets too high the thermal limiter will de-rate the power output. Simple adjustment to correct the bias for a tech.

[Z-Bass]

Thanks. I'll try the patch cable in the effects loop at next rehearsal to see if that clears things up.

Regarding the heat sink bias, I'll add that I had used the amp at many rehearsals prior to this occurring without failure. I won't lie, I was pushing the amp but not into it's upper limits. The heat sink felt warm but not at all hot. This started happening all of sudden. But it is a '92 and I did buy used. Maybe just needs to TLC (hopefully).

[skychief]

If all else fails, check the Molex connectors . They build up a patina on them and can go intermittently open, causing loss of signal. Usually just the action of unplugging them and re-plugging them a few times can break up the patina.

[B-string]

It is output transistor bias by the way. The heat sink would be hot before it started to de-rate. More than likely the effects return jack as the amp heats the metal the contacts are on looses some tension on a corroded connection (especially if you never use the jack). A 21 year old amp could always benefit from a checkup and general maintenance

[B-string]

Originally Posted by skychief

If all else fails, check the Molex connectors . They build up a patina on them and can go intermittently open, causing loss of signal. Usually just the action of unplugging them and re-plugging them a few times can break up the patina.

Patina, not a bad layman's term for the microscopic fretting of low voltage connections. May use that myself as it is much more visual.

[skychief]

Originally Posted by B-string

Patina, not a bad layman's term for the microscopic fretting of low voltage connections. May use that myself as it is much more visual.

Roger that, B.


The "fretting" on my '86 RB800 was so bad, I could actually see it (fine white powdery residue) & scrape it off with a knife.(which i did).

I live pretty close to the ocean, so exposure to the salty air probably hastens that process considerably.