Traynor YVM-1 much needed repair

[fossilshark]

Hi all, back with another doozy. My rythm guitarist saved this YVM-1 from destruction a few years ago and in 2020 I replaced the filter caps, removed the death switch, threw in some electro harmonix tubes, and biased it. Since then it has been his favorite amp to play.

Its always had this issue where distortion just sounds like crap through it (in my opinion) and recently it started doing this thing where when you strike a note the volume drops quickly before going back to normal (power supply sag?). Any ideas how I can fix this?

Furthermore it was converted to EL34s at some point and channel 4 seems to be modded to take guitar better. The pots are clearly original but seem to work fine after I hit them with the magic spray. I would like to mod it to sound closer to a JCM800 (as thats what I play and when we jam he just sounds boomy and muddy).

I don't know where to start and to be honest I am kind of afraid of this thing 

Any advice on how I can get this sounding a bit better is greatly appreciated.

[fossilshark]

I believe this is the schematic for this unit but like I said its been converted to EL34 and quite frankly been through alot.

[PRR]

6CA7 and EL34 are practically the same thing.

I would try 10k-47k in series with each EL34 signal grid right AT pin 5.

Being a vocal mixer, it may never be a great guitar amp.

[fossilshark]

I will definitely try that thanks. I also suspect there isn't much ill be able to do but we shall see.

[bmccowan]

If that does not help much. Why not scrap the existing board - it looks pretty crusty anyway - and build up a new circuit? You have a lot of what you need to build the 2xEL34 of your choice. I see the preamp tubes are grid leak bias, but that's easy enough to change. Of course I love oddball projects and you may not.

[fossilshark]

I may rebuild the board as its clearly on its last legs. My friend would like to keep this stock as much as possible and make an original looking cabinet, I don't think he will want me to rebuild this into a completely new amp (as much as I would like to).

I will try PRRs idea and if that doesn't help much ill try to convince my friend to let me turn it into a jcm800 

[Latole]

If that does not help much. Why not scrap the existing board - it looks pretty crusty anyway - and build up a new circuit?

IMO no need to do that. The board is ok.

This amp can easily mod to a good guitar amp .

[sluckey]

If that does not help much. Why not scrap the existing board - it looks pretty crusty anyway - and build up a new circuit?

IMO no need to do that. The board is ok.

This amp can easily mod to a good guitar amp .

Did you look at the pics of this board? The board looks like shit and so does the soldering job!

[Latole]

If that does not help much. Why not scrap the existing board - it looks pretty crusty anyway - and build up a new circuit?

IMO no need to do that. The board is ok.

This amp can easily mod to a good guitar amp .

Did you look at the pics of this board? The board looks like shit and so does the soldering job!

It is a old board easy to fix for me

[shooter]

 
as long as all your shots are up to date!  maybe talk to the Doc about mold in the lungs 

[fossilshark]

haha yes that board is crusty. But if nobody has concerns about the OEM capacitors then im not too worried. the wiring on the other hand is very sketch.

If that does not help much. Why not scrap the existing board - it looks pretty crusty anyway - and build up a new circuit?

IMO no need to do that. The board is ok.

This amp can easily mod to a good guitar amp .

do you have any suggestions latole on any values i should change to make it take distortion better?

[sluckey]

I would convert only the first preamp from grid leak bias to cathode bias. Like the attached pic. Notice R5 has also changed to a 100K. This should take distortion pedals better. If so, then consider converting some more preamps.