Egnater amp class marshall JCM800 noise issues

[Curranproducer]

I have a wonderful Egnater JCM800(mojo tone) kit amp I built at one of Bruce E's amp classes in Michigan years ago! It has been a staple here in my studio and now it needs some help. I noticed some hissing and popping in the amp and if I smack it then big explosions of noise happen through the cab. I wiggled the tubes and found the V1 tube to be microphonic and the PI tube to make huge smashing and banging sounds through the amp when I wiggle it. I re-tubed it and Biased the amp and it does sound better, I also re-tensioned the PI Socket and cleaned all the sockets. I did also change the main input jack from the plastic cliff jacks to a switchcraft 12a. When I was smacking the amp I blew the B+ fuse in the amp, which was weird, and this prompted the tube re-do. the PI is still noisy as all get out when you wiggle is and the amp itself seems a bit fizzy now. If I chop stick through the board it is very noisy and the tapping of the chop stock comes through the amp, as well as the occasional loud bang or explosion of noise. I am thinking I should replace the tube socket on the PI and also replace the Carbon Comp resistors on the plates. I have had the amp for years now(5-6) and it does get used with some regularity, I just want to quiet it down and get the fragile as glass feeling out of the amp when I am handling it.

[xtian]

Blew a fuse by smacking the amp?!? First guess is one or more intermittent connections, possibly in the power string. Dropping resistor going south? Chopsticking around should help you locate the trouble.

If plate resistors are going, they'll usually make "bacon frying" sounds on their own, without chopsticking.

In addition to tubes, coupling and snubber caps can be microphonic. Again, tapping them with a chopstick can help identify.

[Curranproducer]

when I chop stock through the board it is just plain noisy. I am pretty sure the bacon fry thing is in the plate resistors since it is a hard working amp AND all carbon comp resistors. Where are the snubbing caps on an amp like this. i have schematics and layouts for this amp but I am still a noob when I comes to certain things

[xtian]

I'm not saying it has any snubbers. Just guessing.

[Curranproducer]

oh Ahhhhhhhhh (FNG driving peeps cray zay)

[statorvane]

when I chop stock through the board it is just plain noisy.

There's a technique to this. Chopsticking in my experience usually reveals a lose solder joint . Try chopsticking the various wires. If you find one that is microphonic, then there is a bad electrical connection at one end or the other.

[Curranproducer]

changed up the plate resistors on each stage of the amp, V1 V2 and the PI, things got much better as far as noise, I still have issue with the tubes POPPING and BANGING when I wiggle them in the sockets, more so in the PI socket. so I am putting in replacement ceramic sockets today. I am hoping this will take care of the last of my issues with the amp. this thing is so awesome sounding and full of dimensional tone!!!!

[Stevem]

First get rid of the blowing fuse issue and deal with the hiss latter!
You likely as posted before have a failed solder connection, or a bad power tube.
To diagnos the power tube tube thing place them in another amp if you can, or install them back in this amp one at a time and smak the amp and tube around and try and reproduce that noise.

Just because you have good tension in the tube socket does not mean that the tube pins them selves are clean enough for making good connections, and a poor connection in the preamp section can make for a high resistance and high noise in turn!

You may also have noisy 68k carbon types on the input jacks, and these can make a ton of noise as you have all the total gain stages in the amp jacking up the noise!

[Curranproducer]

I re-tubed it 1st to see about the noises and banging stuff. I have tried to clean the sockets, and now I am moving to replace them on principle. the tubes all seem good as far as the tapping and chop stick tests for noise and microphonics. I already replaced the CC68k's with dale metal films a few months ago to get rid of the RFI. I will post back after the socket swap!

[Reeltarded]

Chopstick away but so carefully as to barely rub on each component. Don't tap it, scrub along the bits and you will find the ugly one.

[Curranproducer]

cool will do!

[Stevem]

Hey , you got 3 amp repairs up on here we are helping you out with, when do we get a cut of the action !? Lol!

[Curranproducer]

well, two of them are my personal amps(the trainwreck and the Egnater) the 3rd one is a friends since we seem to not have anyone worth a damn here in akron for tube amp repairs. I can vouch for this since I wouldn't take my gear to any of the clown shops in this fucking town!!!! And being a noob to the entire adventure of amp building and now trouble shooting and repair you guys here are super skin saving!!! HAHAHAHAHA

[Curranproducer]

On a side note! I replaced the sockets and all the plates resistors and MAN ALIVE I remember why I love this amp!!! Power and tone for days, and now I can hit it with a hammer and NOTHING but dents and shattering glass!!! HAHAHA J/K no more banging explosion noises or anything!!!! Love this amp!

[Reeltarded]

Good deal!