Help!!! Hot rod deluxe noise

[Barakuda]

Hello everybody,

I have another hot rod deluxe that make a loud noise after a 10 minutes power on, and after, if i power off and on the noise come immidietly (when the amp is hot).
The problem starts after i forgot the amp 7 hours on. (Heard a loud noise suddenly)

In clean channel i cant control the noise with volume pot
In drive channel the master vol is controlling the noise.
When i plug the guitar to power amp in the noise stops.
So i think the preamp is bad. It is background loud noise and i hear the guitar with the noise

I replaced all the tubes,
The input jacks is good (new outside pcb)
All electrolitic capacitors replaced before a year (fromel supreme mod with recap kit)
I replaced all the preamp resistors (about 30 resistors)
I replaced 5w 470ohm resistors r78,r79
Replaced r57,58
Somebody have an idea?
I resoldered all points of the two pcb's


Link for video problem:
https://vid.me/A3FP

[nickb]

Has the the clean channel become noisier too?

What effect do the drive & tone controls have on it?

Best to approach logically, but my best guess without any more info would be the 100K plate resistor of V1A ( R4) is bad.

[Barakuda]

There is a loud noise in the clean channel (clean volume doesnt affect the noise)
The eq controls in both chnnels are working and changing the noise sound
Only in drive channel i can move down master volume to 0 and the noise will turn down.
I changed all the resistors in preamp section include r4
Still have a noise.
Thank you

[nickb]

That tells us it's after the clean pot R6 and before the tone stack. That narrows it down to about half a dozen components. I did see that you had changed all those resistors but I didn't know if that was before or after the problem occurred. Also, new parts can be faulty.

To confirm, pull V1 and the noise should go away. If that worked, then put it back in and let's do a test to see if the noise is on the grid on V1B - add a 0.1uF capacitor between pins 7 and 8 of V1 to kill any signal coming in.

[gbono]

https://www.youtube.com/watch?v=Z_16JSYzA8Y

maybe?

[Barakuda]

Thank you
I think i have the same problem
When im pulling v1 the noise dont stopping
When im pullling v2 there is no noise anymore
So it somwere between volume pot to the eq pot it the schematic like nickb said.
The resistora their has changed so the capacitors is my next replacment.
Thank you for the video

[nickb]

If pulling V1 didn't do it, then that only leaves the tonestack - the caps would be the first suspect- same as the video.

[Tone Meister]

If you (or someone else) installed the Fromel mod, then it came with a 250 pF silver mica treble cap (C7). Those are very easy to overheat, which will compromise its integrity and many times show up in the form of the noise you're describing.

Try swapping out that C7 cap, and if using another silver mica cap, use a heatsink and get your iron pretty hot (670-700 degrees) and "get in and get out, " meaning don't leave the iron on the solder pads very long.

[Barakuda]

Yes, i installed the mod and all this 3 capacitors has changed . (Part of them to other valves)
Today i will replace the silver mica cap first... i have a feeling that it will work...

[Barakuda]

I replaced c7 and i think the problem solved!!!
The amp is power on almost 2 hours and the is no noise.
Tone meister - i replaced all the preamp resistors to stock value and i would like to return back to fromel mod (because some of the capacitors has changed )
Do you know which resistors has changed her value?
I know r12 is changed from 130k to 100k in the tone stack for example.
Anyway thanks you all

[Tone Meister]

I replaced c7 and i think the problem solved!!!
The amp is power on almost 2 hours and the is no noise.
Tone meister - i replaced all the preamp resistors to stock value and i would like to return back to fromel mod (because some of the capacitors has changed )
Do you know which resistors has changed her value?
I know r12 is changed from 130k to 100k in the tone stack for example.
Anyway thanks you all

R12 is the slope resistor for the tone stack and stock value for vintage Fender amps is 100K. Many folks prefer that value over the Hot Rod 120K stock value, myself included. If the amp is working now with no problems, I'd suggest that you do another close inspection of your work and leave it alone.

There isn't anything inherently magic about the Fromel "mod kit" but it does include several standard reliability improvements and the amps generally sound much better afterward. I would suggest that you leave well enough alone and put it back together if it's working now.

But definitely check your work closely while you have the board peeled back.