1986 GK 400RB schematic

[e_c_mccollum]

Looking for the preamp schematic for the 1986 GK 400RB with boost channel and 1/4 direct out. The 200 watt amp schematic would be good to have if avaiable too.

Not sure, but that TL604 chip may be out. I know their obsolete. What can I use??

[gibsonripper]

I have a copy of the GK 400RB schematic (actually, the service manual).
I can't remember if GK has a few of those chips, but you might want to contact them to see if they still have some "reserve" stock, just for this purpose. If they don't, then you can remove the I.C. and just jump from pin-3 to pin-7. I've done this for several of my customers who didn't want to bother with a replacement. This scenario is the same as having the boost on all the time. That is, you can still control the level of boost, as if the amp were in it's normal state (no footswitch plugged in). If you don't use a footswitch to boost, than this is not only acceptable, but no different than having the I.C. in the circuit anyhow.

[e_c_mccollum]

I'll probably just remove the chip and jump the pins. I would like a pdf copy of the schematic if possible.

[doctor]

I have a copy of the GK 400RB schematic (actually, the service manual).
I can't remember if GK has a few of those chips, but you might want to contact them to see if they still have some "reserve" stock, just for this purpose. If they don't, then you can remove the I.C. and just jump from pin-3 to pin-7. I've done this for several of my customers who didn't want to bother with a replacement. This scenario is the same as having the boost on all the time. That is, you can still control the level of boost, as if the amp were in it's normal state (no footswitch plugged in). If you don't use a footswitch to boost, than this is not only acceptable, but no different than having the I.C. in the circuit anyhow.

Gallien Krueger 400RB preamp schematics

[Enzo]

Peavey used a ton of the TL604 back in the 1980s. When the IC became history, they made up a small board with long pins, you install it in the same pc board holes and it does the function. Not as cheap as a jumper wire, but if you want to keep control over that switchable function it is worth the price. Their parts department would sell you one.

On amps with more than one 604, sometimes you can move them around. For example, I'd rather have reverb always on that be stuck in one channel. SO if the channel switching 604 dies, I jumper the reverb one and move its good IC to the channel switch spot.

[gibsonripper]

I can email you a copy of the service manual. No problem... where should I send it to?

[e_c_mccollum]

Thanks...... I'll just use the pdf's you sent. More than enough......

[ferrox]

service manual

hello gibsonripper, could you send me a copy of service manual GK 400RB to my mail. Thanks, see you

........................................................ ...........................................
I can email you a copy of the service manual. No problem... where should I send it to?

[J M Fahey]

Please try to post it here, for future reference for others.
Thanks.

[letsonwilliams]

I can email you a copy of the service manual. No problem... where should I send it to?

hey man, i could use a copy of the service manual if you wouldn't mind, i'm having power loss issues with my amp.

letson@me.com


thanks!

[gbono]

I would appreciate the schematic for the 400B or service manual - THX

[DrGonz78]

Okay I am gonna post what I have already right now. Here it is... Also, will add more if I find the other ones too.

[doctor]

Okay I am gonna post what I have already right now. Here it is... Also, will add more if I find the other ones too.

Here are the 400B schematics.

[gibsonripper]

Hey everyone, my apologies for having been absent from this particular thread for so long. I was working 60 hours a week for many years, so had little to no time... also, I had all email notifications turned off. I'm turning some of them back on.

Glad to see someone go the 400RB schematics uploaded. Again--I'm sorry for being a deadbeat on this.

[Jazz P Bass]

Welcome back.