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Reverb Howl [message #15453]

Sat, 26 March 2011 20:41

Explorer's Club
Messages: 9
Registered: March 2011

Junior Member

So I saw another topic on this with no resolution. I have the exact same 200 pa head with 4 inputs and vol,trb,bass and rev controls for each channel. I have the reverb disconnected now because it goes into runaway feedback.

The rest of the amp works fine other than the hiss that seems to plague these as things drift.

Is there an easy fix to this or something I can tell a tech if it's not easy?

Also how different are these circuit wise compared to the guitar and bass models? I plan to use this for bass and keys (Rhodes piano and an old combo organ)

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Re: Reverb Howl [message #15463 is a reply to message #15453]

Sun, 27 March 2011 15:13

stevem
Messages: 4733
Registered: June 2004
Location: NY

Senior Member

Hello.
This was a problem with quite a few K200-5 models made before Aug of 68 when Kustom came out with a fix in one of their service letter/service bulletin issues.
The fis involves changing the value of 4 resistors on the PC803 board, so for you or a tech to make these changes you will need a copy of the PC803 schematic which I can fax you if you like around mid week.
If your amp was produced after Aug of 68 the problem could be as I have found in many amps due to the quailty of the connection between the RCA male plugs on the two Reverb cables and the Female RCAs on the 803 board.
Over the the years these Aluminum parts start to look very dull gray in color when they need to be shinny clean to make a good connection.
Also regardless of when your amp was made there is no garranty that at this point in time you still have the right spec Reverb pan in the amp.
The Reverb pan for these amps need to have the pans output jack labled RCA connector grounded to the pan and the amps chassie thru the RCA output cable, the Input side cable has no ground connection point made other than at the pan.
If you PM me your fax number I will blast you out this service bullletin.

[Updated on: Sun, 27 March 2011 15:14]

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Re: Reverb Howl [message #15464 is a reply to message #15463]

Sun, 27 March 2011 17:30

Explorer's Club
Messages: 9
Registered: March 2011

Junior Member

Thanks for that. I'll pm ya with my fax.

I went ahead and just used some contact cleaner on the rca jacks for the board and pan and played it for a good 30-45 min with no issues so maybe that will do it, but I'll check out that service bulletin just to be sure.

Again has anyone compared the overall circuit of the early PA models to the guitar ones. I'm curious if I'm getting in the same ballpark sound by plugging a guitar or bass straight in.

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Re: Reverb Howl [message #15467 is a reply to message #15453]

Mon, 28 March 2011 12:40

chicagobill
Messages: 2005
Registered: April 2003

Senior Member

All of the K200-B series amps shared the same power amp regardless of what preamps were included, so there is no difference as far as the output section is concerned.

As for the preamps in the PA models, they used the very same PC board as the straight non-boost instrument channels. The difference was that the PA channels have a reverb control mounted in place of the bright switch that is included in the instrument preamps.

The PA heads also have an additional mixer/reverb board that the instrument heads do not have, but this will not change the sound much.

So in answer to your sound question, the PA models sound very much the same as any K200B with a non-boost channel, like a K200B-1.

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