RK I feedbacks/squals loudly when reverb is switched on

[IkarusOnFire]

I own a mesa road king series 1 that has served me faithfully for years. Recently, however, a strange problem has occured: whenever i switch on reverb, the amp start squaling and feeding - makes it unplayable - it's quite loud.

- This goes for all 4 channels. It's less prominent in the clean channels.
- The noise occurs also whenever I switch on my fx loop

This is what I have tried:
- changing preamp tube in position V1 - this actually defeated the problem - but alas it reoccured only a week after
- changed preamp tubes one by one to see if it could be another problem. I had no luck (except, with a temporary fix with the v1)
- I have checked that I have russian tubes in v1,v2 and v5
- switched gz34 for 5U4s

What's in my amp:
- 2 x gz34
- 2 x JJ EL34
- 4 x JJ 6L6GC
- v1: JJ ecc83
- v2:JJ ecc83
- v3: JJ ecc83
- v4: JJ ecc83
- v5:JJ ecc83

What's in my fx loop:
- 1 t-rex analog delay pedal

Cables used:
- George L solderless

Guitars used:
- JEH custom with emg's
- JEH custom with BKPs

Amp works perfectly fine in all other states (meaning whenever reverb and/or fx loop is switched off).

Any ideas what this could be - or how I should locate the issue?

Thank you very much in advance!


//Marcus

 

[bendo]

Sound to me like the tube still needs to be replaced, and might have been replaced with a faulty tube. This is typical for the behavior you describe.

I would change the tube again with a KNOWN NEW and GOOD tube. V4 is your reverb stage.

 

[IkarusOnFire]

Sound to me like the tube still needs to be replaced, and might have been replaced with a faulty tube. This is typical for the behavior you describe.

I would change the tube again with a KNOWN NEW and GOOD tube. V4 is your reverb stage.

Thank you kindly - I'll get to work on the v4 then =)

//Marcus

 

[siggy14]

I also own a RK1 and my reverb died, when going through the tubes to try to fix it and found out that on the RK1s the reverb is not tube driven.

It is possible your tanks is going bad or check the cables and make sure they are connected correct.

 

[IkarusOnFire]

I also own a RK1 and my reverb died, when going through the tubes to try to fix it and found out that on the RK1s the reverb is not tube driven.

It is possible your tanks is going bad or check the cables and make sure they are connected correct.

Thanks mate - I've checked the cables on other amps and double checked that everything is connected right. Could you expand on the definition of a "bad tank"? How do I uncover wether or not it is crapping out on me?

I realized also, that I have russian tubes in v3 and v4 - I might try and change theese to some chineese tubes.

//Marcus

 

[siggy14]

The tank would be the reverb unit, I would try switching that out first and see if that will fix the problem.

I also own a RK1 and my reverb died, when going through the tubes to try to fix it and found out that on the RK1s the reverb is not tube driven.

It is possible your tanks is going bad or check the cables and make sure they are connected correct.

Thanks mate - I've checked the cables on other amps and double checked that everything is connected right. Could you expand on the definition of a "bad tank"? How do I uncover wether or not it is crapping out on me?

I realized also, that I have russian tubes in v3 and v4 - I might try and change theese to some chineese tubes.

//Marcus

 

[bendo]

I also own a RK1 and my reverb died, when going through the tubes to try to fix it and found out that on the RK1s the reverb is not tube driven.

It is possible your tanks is going bad or check the cables and make sure they are connected correct.

No, but the circuit is most definitely tube driven. A bad tube in that position will display the characteristics the OP described.

OP. Also make sure the cables are connected in the right order for the reverb tank. If they haven't been touched, I would not worry about it.

siggy, if the reverb tank somehow got damaged, the yes you would be correct.

 

[IkarusOnFire]

I also own a RK1 and my reverb died, when going through the tubes to try to fix it and found out that on the RK1s the reverb is not tube driven.

It is possible your tanks is going bad or check the cables and make sure they are connected correct.

No, but the circuit is most definitely tube driven. A bad tube in that position will display the characteristics the OP described.

OP. Also make sure the cables are connected in the right order for the reverb tank. If they haven't been touched, I would not worry about it.

siggy, if the reverb tank somehow got damaged, the yes you would be correct.

I will try both - can't hurt to buy a couple of new tubes and pull out the reverb tank and check it too I will let you know if it resolves the problem. I am grateful that for you help so far

//Marcus

 

[IkarusOnFire]

I pulled out the amp from the chassis, cleaned the contacts, put in a new set of preamp tubes all together - figured and did some testing with the old ones, to see if any were faulty. I found v4 to be faulty Reverb now works perfectly fine, as does my loop. Thank you very much guys! I know also know to check the tank if a similar problem persists

I might also add, that a couple of sovtek ecc83 LPS in v1 and v5 made this amp really snappy! Might've been the cleaning of the sockets too though - but it sounds awesome now. Cheers!


//Marcus

 

[bendo]

Glad to hear it worked out! We are here for help anytime. 8)