Attention Amp Gurus and Bench Warriors!

[KJRH]

Re: Attention Amp Gurus and Bench Warriors!

Okay, here's the update on the squealing verb pot. problem with the FSR. I did try different and new tubes throughout, save for the power tubes and rectifier valve, cleaned the RCA connectors and the valve pin sockets. Didn't improve things, in fact it may have made matters worse - now the Vibrato is also emitting microphinic chirping sounds when the intensity is turned up.
The reverb tank isn't the problem, as I connected the tank and wires from the 66' FSR to the 65' with the same results. I took the chassis out and cleaned all the pots with Deoxit, checked for loose or contacting wire that shouldn't be - it all seems to be in order. I traced the two wire connecting the pot for the reverb into a hole in the board that supports the various tone caps, but I did look underneath to see where they went from there. I did notice that the control panel where the pots are also seem to be slightly microphonic when tapped. The problem persists regardless of whether the reverb is connected or not, and whether there in a tube in V4 or not. Otherwise the amp seems to work fine when the reverb pot is dialed below 3, and the vibrato intensity pot is not up past 7. Any more ideas? Please save the jokes. Thanks!

 

[Gtrjunior]

Re: Attention Amp Gurus and Bench Warriors!

Do you have a local amp guy you can take it to? (I didn’t go back and see if you had already answered this).
You’ve tried everything I could think of and more.

 

[ehdwuld]

Re: Attention Amp Gurus and Bench Warriors!

While you had it out
Did you take the opportunity to touch the top of the tube socket solder joints with a hot iron?

 

[Tone Meister]

Re: Attention Amp Gurus and Bench Warriors!

Look inside the chassis, on the bottom, right underneath the controls. See that brass plate with bare braided wires coming from the tone controls and soldered to the brass plate? Those are grounds for the tone stack. Check to see if any of those grounds are any broken or if there is any excessive corrosion on or around those grounds. If they do need re-soldering, you will need a very high wattage soldering iron with a huge tip.

 

[Tone Meister]

Re: Attention Amp Gurus and Bench Warriors!

While in there, with the amplifier on and while exercising all tube amp precautions, grab yourself a wooden or plastic chopstick or anything non-conductive you can use to safely poke around inside the amp.

See the yellow and brown wires coming off the Reverb control? Follow those wires to the hole in the board - right next to that hole will be an eyelet where 3 resistors and a tiny ceramic capacitor all come together. Poke each of those resistors, and especially that tiny cap and see if you can induce noise.

Also, gently poke each wire on the V3 and V4 tube sockets, checking for poor connections or wires about to break.

 

[KJRH]

Re: Attention Amp Gurus and Bench Warriors!

EHD, that was the one thing that I did not do, as I thought I would have to drain the filter caps before sticking soldering irons into the tube sockets. However, I have been looking at several u-tube vids that illustrated that it could very well be a mechanical issue such as what you are suggesting. I will check into it the next time I pull the chassis. Thanks!

 

[KJRH]

Re: Attention Amp Gurus and Bench Warriors!

Thanks T.M! I'll check it out the next time I get a chance to pull the chassis. After watching a load of u-tube vids on the subject, I am beginning to think that the issue could be a faulty resister, or some mechanical issue with the wiring. The saga continues - unfortunately!

 

[KJRH]

Re: Attention Amp Gurus and Bench Warriors!

Yes, but not until I've exhausted the possibilities. However, it's quite possible that I'll have to go that route. Cheers!

 

[KJRH]

Re: Attention Amp Gurus and Bench Warriors!

Okay, here's the latest update on the on the Super Reverb issue (not re-issue).
I took the chassis out again and touched the tops of each tube socket solder joints with a hot iron, as recommended by ehdwuld, re-cleaned the sockets, changes the rectifier and power tubes - biased them, and cleaned the chassis. Afterwards I let the amp warm up agin and tested it to see if the problem persisted. With all of the control pots turned down, I plugged a guitar into it and turned the volume up. The sound was okay, but seemed to be lacking in volume, even on ten. Turning up the treble and bass added more volume, but before I got to the reverb pot the fuse blew. I again removed the chassis, and noticed that one of the resisters on the board had some fuzzy white stuff covering one of its lead wires which makes me think the stuff came out of the resister and that resister is bad. No other signs of damage was noticed, but since I am out of 2amp slow fusses, I can not check it again. So, at this point I have exhaused my limited capabilities at trouble shooting, and will defer to an amp repair person, as Gtrjunior suggested. Hopefully I didn't make matters worse than they were from the start. Thanks all!

 

[Gtrjunior]

Re: Attention Amp Gurus and Bench Warriors!

Okay, here's the latest update on the on the Super Reverb issue (not re-issue).
I took the chassis out again and touched the tops of each tube socket solder joints with a hot iron, as recommended by ehdwuld, re-cleaned the sockets, changes the rectifier and power tubes - biased them, and cleaned the chassis. Afterwards I let the amp warm up agin and tested it to see if the problem persisted. With all of the control pots turned down, I plugged a guitar into it and turned the volume up. The sound was okay, but seemed to be lacking in volume, even on ten. Turning up the treble and bass added more volume, but before I got to the reverb pot the fuse blew. I again removed the chassis, and noticed that one of the resisters on the board had some fuzzy white stuff covering one of its lead wires which makes me think the stuff came out of the resister and that resister is bad. No other signs of damage was noticed, but since I am out of 2amp slow fusses, I can not check it again. So, at this point I have exhaused my limited capabilities at trouble shooting, and will defer to an amp repair person, as Gtrjunior suggested. Hopefully I didn't make matters worse than they were from the start. Thanks all!

Bummer man...
You gave it a great effort though.
Let us know what the fix is!

 

[ehdwuld]

Re: Attention Amp Gurus and Bench Warriors!

At least you have found your limits
Exhale
We have all found a point where we need assistance
Now you know where yours is

Next time you may be able to push that wall back a bit farther
But for now it is time to call it

Good luck
Keep us posted

 

[GoldenVulture]

Re: Attention Amp Gurus and Bench Warriors!

Okay, here's the latest update on the on the Super Reverb issue (not re-issue).
I took the chassis out again and touched the tops of each tube socket solder joints with a hot iron, as recommended by ehdwuld, re-cleaned the sockets, changes the rectifier and power tubes - biased them, and cleaned the chassis. Afterwards I let the amp warm up agin and tested it to see if the problem persisted. With all of the control pots turned down, I plugged a guitar into it and turned the volume up. The sound was okay, but seemed to be lacking in volume, even on ten. Turning up the treble and bass added more volume, but before I got to the reverb pot the fuse blew. I again removed the chassis, and noticed that one of the resisters on the board had some fuzzy white stuff covering one of its lead wires which makes me think the stuff came out of the resister and that resister is bad. No other signs of damage was noticed, but since I am out of 2amp slow fusses, I can not check it again. So, at this point I have exhaused my limited capabilities at trouble shooting, and will defer to an amp repair person, as Gtrjunior suggested. Hopefully I didn't make matters worse than they were from the start. Thanks all!

That's unusual, resistors dispelling anything. They usually go brown in the centre [ like the one in the pic from the 5F1 build ] or are visibly burnt in the centre. I'm not saying it isn't the resistor, just that it's unusual for one to do that.

 

[NegativeEase]

Re: Attention Amp Gurus and Bench Warriors!

That's unusual, resistors dispelling anything. They usually go brown in the centre [ like the one in the pic from the 5F1 build ] or are visibly burnt in the centre. I'm not saying it isn't the resistor, just that it's unusual for one to do that.

Thats a great looking amp -I could eat dinner off that layout.

 

[Tone Meister]

Re: Attention Amp Gurus and Bench Warriors!

Where do you live?

 

[KJRH]

Re: Attention Amp Gurus and Bench Warriors!

Yes, I know it sounds a bit unusual, and perhaps it is just some sort of mold of some sort on that end of the resister wire. None of the resisters appear to be burnt, and no burnt smell. I did find some small bits of metal debris loose in the chassis when I opened it again after the fuse blew.One bit was a bare wire about three eights of an inch, which may have have been touching something that caused the fuse to blow. At any rate, I can not check that theory until I get more fuses. When I do, I'll see if another fuse blows, and if so, I'll know it's time to take the amp to a technician. Thanks for your input, and interest!

 

[KJRH]

Re: Attention Amp Gurus and Bench Warriors!

Currently, I am based in Houston (Tx.).

 

[Tone Meister]

Re: Attention Amp Gurus and Bench Warriors!

Don't feed the amp fuses. It's likely you made some solder bridges (shorts) when doing the touch up. Since you're taking it to a tech, leave well enough alone in order to prevemt more possible damage.

 

[LLL]

Re: Attention Amp Gurus and Bench Warriors!

Caps leak white stuff; not resistors. They go bad or get old and give up.

 

[ehdwuld]

Re: Attention Amp Gurus and Bench Warriors!

The problem has gotten worse
From a howl to blown fuses

The resistor is probably cap if its leaking

Take it to a tech
I applauded you for recognizing you couldn't fix it

Dont make me take that back
Stop before you hurt yourself

 

[Gtrjunior]

Re: Attention Amp Gurus and Bench Warriors!

Lol. But yeah, good advise.
It’s important to know when the say when.