66 Deluxe Rev cutting out

[jimmybcool]

as the title says. Works fine provided I turn the intensity knob to 0.

If you think this is a tube could you tell me which one so I don't experiment with all of them?

Thanks

[zenas]

Is the amp cutting out or just the reverb?
When was the last time a a GOOD techs looked at this? It could be a tube or a bad solder joint.
Can you give a bit more onfo?

[jimmybcool]

Thanks for the response.

In the dry channel there is no issue. In the wet channel I can do what I want with reverb and volume provided the intensity knob for the vibrato is all the way off and there is no problem. When I turn the intensity knob on the volume level cuts in and out and there is static/distortion.

I haven't' a clue when a tech last saw this amp. I purchased it last July and have been gone 3 months so I have little time spent with it. Since this post I have ordered a full complement of new tubes for it.

My assumption (I am no amp tech) is that since this only happens when the vibrato is activated is that the signal path shares a common tube with the vibrato function which works OK until the vibrato kicks in.

[soldersucker]

Try cleaning the pot first.

[Blue Strat]

If you haven't yet, unplug both foot switches and see what happens.

[jimmybcool]

Hi,

I tried it without the footswitch. No change. I don't have anything to clean the pot with. What do yo use? Compressed air?

BTW, the problem comes and goes with the pot in one position if that makes a difference.

Thanks

[Blue Strat]

Hi,

I tried it without the footswitch. No change. I don't have anything to clean the pot with. What do yo use? Compressed air?

BTW, the problem comes and goes with the pot in one position if that makes a difference.

Thanks

Could still be the pot. Caig DeOxit (online) or "tuner cleaner" from Radio Shack.

[jimmybcool]

Could still be the pot. Caig DeOxit (online) or "tuner cleaner" from Radio Shack.

OK. I'll see if I can get some and give it a try. Thanks

[zenas]

I don't think it's a dirty pot. Anyway you could post some gut shots ?
Seems to me that if you pulled the footswitch that shuts the trem off so it should change things. But even with the trem off on these thay still affect things that's why some guys disconect the trem or put a switch in.
Look for bad grounds and cold solder joints while your in there. (Or maybe some modding)

Just for fun try pulling V5 the trem tube and see what happens. If it goes away try another tube.

[jimmybcool]

I'll give V5 a shot. I've been like a chicken with its head off lately but today I'm free. Other than I have to meet a guy who is delivering my new (to me) 64 Vibroverb. :banana

[Mr. SD-1]

The issue is not tube related.

[jimmybcool]

OK. I'm putting off troubleshooting until the new set of tubes arrives. When I change them all out I'll see what happens.

If it isn't tube related and that fails to fix the problem where do you suggest I look?

[Mr. SD-1]

replace intensity pot

[zenas]

If the tube doesn't do it. One other thing that will make a pot noisy is DC voltage from a coupling cap, tone cap (or whatever we're calling these things today). These almost never go bad in these amps.

[jimmybcool]

Thanks guys. I receive the new tube complement tomorrow per USPS. If that doesn't work I'll give a new intensity pot a shot and look at the caps.

Lucky me I am distracted anyway with my brand new (to me) 64 Vibroberb. :bounce

I got a feeling I might need to learn a bit about maintenance of these things. Any decent books on these old Fender amps out there? I was (at one time long ago and far away) a graduate of a technical school as an electronics technician. I might still remember some of that. Not that I own a working multimeter or soldering iron (which might be a good thing).

I am particularly curious about my upcoming retube and "bias". I'm wondering if I need to do that or if I CAN do that.

[zenas]

Lots of good books on amp repair and most are full of Fender info. Gerald Weber has a few and I think it's Dave Funk that has a book or two Aspen Pitmen as well.
G Weber has DVDs out that may be very helpful haven't seen them myself.
Just never forget you can get a hell of a shock working on amps even unplugged. The books will cover that as well.
Oh and Vibroverps aren't worth a crap I'd be glad to take it off your hands for say 50 bucks. I'm so nice I'd even drive down and pick it up for that!

[Blue Strat]

Also clean all sockets and existing tube pins. One oxidized pin can wreak havoc with any function of an amp. It's easy to do and eliminates one possible problem from contention.

[jimmybcool]

Lots of good books on amp repair and most are full of Fender info. Gerald Weber has a few and I think it's Dave Funk that has a book or two Aspen Pitmen as well.
G Weber has DVDs out that may be very helpful haven't seen them myself.
Just never forget you can get a hell of a shock working on amps even unplugged. The books will cover that as well.
Oh and Vibroverps aren't worth a crap I'd be glad to take it off your hands for say 50 bucks. I'm so nice I'd even drive down and pick it up for that!

Thanks for that. BTW, I'll have the Vibroverb on the curb by 10 AM. Pick it up at your leisure. :p

Blue Strat - good idea. I just got it and it may have sat for a while. I'm really waiting for tomorrow to start anything. I have a new guitar teacher who is a 50 year professional player and former employee in Fender in the amps department. He isn't a tech but he knows about Fender amps from 50 years of playing thru them and modding them himself. This first lesson might be spent looking at amps and discussing goals.

[jimmybcool]

Just an update for those of you offering guidance. I appreciate the help.

Today I received my new tube complement from Eurotubes. I installed them in the amp and as predicted this did not resolve the problem.

I have spoken with a local amp tech here and will be taking it to him. It is his opinion over the phone that I have a bad capacitor. In any event, there are a few other things I wanted done and don't want to do myself like proper bias and repair the frayed looking connections to the reverb tank. And check for aging caps.

I got to say that with the new tubes and the intensity switch to 0 the amp sounds GREAT. Those tubes really made a difference. I can't wait to get it back from the tech.

When I get it back I'll update again.

And again, thanks for all the help.

[jimmybcool]

OK, I got my amp back from the tech. And the problem was (drum roll):

shorted lead on photo cell in vibrato assembly

Weird problem.

[mxvin]

I don't think it's a dirty pot. Anyway you could post some gut shots ?
Seems to me that if you pulled the footswitch that shuts the trem off so it should change things. But even with the trem off on these thay still affect things that's why some guys disconect the trem or put a switch in.
Look for bad grounds and cold solder joints while your in there. (Or maybe some modding)

Just for fun try pulling V5 the trem tube and see what happens. If it goes away try another tube.
the intensity pot can be a culprit here.

[zenas]

Glad to hear you got it fixed !

[jimmybcool]

Thanks. Now that it is fixed and retubed it is MUCH louder too. And I am discovering I have a speaker about done. Get to replace that next. THEN it should be golden :p

[mrface2112]

shorted lead on photo cell in vibrato assembly This is why it's often virtually impossible to diagnose a problem over the internet. This is typically the sort of problem that one discovers by poking around inside with a chopstick.

Glad you got it sorted out!

cheers,
wade

[jimmybcool]

This is why it's often virtually impossible to diagnose a problem over the internet. This is typically the sort of problem that one discovers by poking around inside with a chopstick.

Glad you got it sorted out!

cheers,
wade

Yeah. Sometimes it is a "common problem" with a product and experienced owners can spot it right off. That was my hope. But if they can't no harm and no holding anyone accountable like they should have known. I mean, they are also working based on incomplete problem definition from the owner - ME. :rotflmao

[phsyconoodler]

Never heard of a shorted trem connection having anything at all to do with reverb.The two circuits are separate completely.
I'd sure like to know how that had anything to do with it.

[jimmybcool]

Never heard of a shorted trem connection having anything at all to do with reverb.The two circuits are separate completely.
I'd sure like to know how that had anything to do with it.

The reverb wasn't the problem. The volume would cut out due to some short in the vibrato circuit. And I have no clue how they interact. :bonk

[phsyconoodler]

Ah,yes! The vibrato connects to the phase inverter and that's definitely going to do funny things to the volume.Good news on getting it fixed!

[jimmybcool]

The tech did say something about an inverter. Lost me there. :rotflmao