OT - Fender Twin Reverb Reissue Problem - Reverb and Crackle

[mikemaddux]

RCA cables are working fine

Reverb tank is fine - took it out and tried it with a new twin reverb reissue and it worked fine (That amp's reverb tank gave me the same results)

the return is working fine - I hear the reverb loud and clear when I tap on the tank

the tube is working fine - swapped it with the new twin reverb's and mine actually sounded a bit better (unexpected)

with both amps side by side my reverb on 10 sounds like it's reverb on 3

Am I just doomed to my own personal hell of Fender amps with no reverb??? lol

All kidding aside, Any and all help you guys give me is much appreciated....Id like to take it back to the tech that just repaired it and give him a better idea where to look for the problem at...

[wavley]

Just an opinion, I think that it's sad that a tech would give it back to you not working and make you diagnose it for him.  A tech's job is to diagnose and repair problems, it's his only reason for being.  My old boss would have yelled at me for an hour if I charged someone for a repair that wasn't complete.  Of course it's almost an obsession for me to "find out what the heck is wrong with this danged thing"... of course that's the sanitized version of the drunken sailor thought that's in my head after a few hours on the bench.

Enough talking smack about someone that I've never met, I somewhat apologize for my outburst.

Keep us posted and I'll try to help however I can no matter how stab in the dark it may be sometimes.

[Paul Marossy]

Just an opinion, I think that it's sad that a tech would give it back to you not working and make you diagnose it for him.  A tech's job is to diagnose and repair problems, it's his only reason for being. 

Agreed. Unless it was working in his shop and something happened to it during transport. Which would seem to point to a mechanical connection... like a dodgy ribbon cable?

[gmoon]

This is reaching a bit--check the ground connection on the input transducer. If the reverb signal is very weak, you might be hearing only the mechanical vibration of the cab.

I've had amps where the reverb tank input cable wasn't grounded, and the input / output shared the output ground. Prevents a ground loop, I suspect. In my case, a replacement tank wouldn't work until the ground was bridged inside the tank itself.

I guess this is a vote for "loose connection" at the input...

[MikeH]

Just an opinion, I think that it's sad that a tech would give it back to you not working and make you diagnose it for him.  A tech's job is to diagnose and repair problems, it's his only reason for being.  My old boss would have yelled at me for an hour if I charged someone for a repair that wasn't complete.  Of course it's almost an obsession for me to "find out what the heck is wrong with this danged thing"... of course that's the sanitized version of the drunken sailor thought that's in my head after a few hours on the bench.

Enough talking smack about someone that I've never met, I somewhat apologize for my outburst.

Keep us posted and I'll try to help however I can no matter how stab in the dark it may be sometimes.

I don't think this is smack- the tech should have gotten it right the first time!

I have a really obvious question but I'd be remiss if I didn't ask: Is the reverb tank perhaps connected backwards?

[mikemaddux]

Tech is a Fender authorized tech (and many other brands) that has done great work for many of my clients for many years....

I have spoke to him and he has agreed to take a second look at it....

The tank is not connected backwards.....

Seeing as though the problem was happening before I took it in the shop - then the tech "repaired" it - and the same thing is happening now, I don't believe anything was damaged in transport.  BTW, the tank wires and tubes are fine - I cant say anything for the ribbon cables inside the amp...

And the tubes have all checked out good in a tube tester....if I didnt mention that before...

[Ronsonic]

Tech is a Fender authorized tech (and many other brands) that has done great work for many of my clients for many years....

I have spoke to him and he has agreed to take a second look at it....

The tank is not connected backwards.....

Seeing as though the problem was happening before I took it in the shop - then the tech "repaired" it - and the same thing is happening now, I don't believe anything was damaged in transport.  BTW, the tank wires and tubes are fine - I cant say anything for the ribbon cables inside the amp...

And the tubes have all checked out good in a tube tester....if I didnt mention that before...

Easy enough to check the drive side of a Fender reverb, connect it to an 8 Ohm speaker or load and see what it's putting out.

The input side of the tank should show about one ohm DCR on your meter. The secondary of the drive transformer will also show about an ohm DCR. I throw my ESR meter on things like that, it'll show a lot more than one Ohm but not open. The primary, I forget what you'll read on that but easy enough to look up.

IIRC the reverb drive ckt is one of the few hardwired bits in there, tranny connects to RCA jack. This is the same design Fender used for 50 years so it should be simple enough to get sorted.   

[Ronsonic]

New Fenders have a TERRIBLE problem with solder cracks.  I would also suspect the ribbon cables coming from the controls to the board. 

I've heard a lot about cracking solder joints in the new Fender amps. That's another good possibility. Ribbon cables are less likely to fail, but it's possible that it might have a dodgy connection in it.

The only reason that I suspect the ribbon cables is because they are the pierce the insulation type cables.  The Mackie 1604 mixer makes me suspect ribbons more than I should sometimes, they were on like Rev. G or H when I left the shop four years ago.  It was the joke around the shop when somebody brought a 1604 in that had been in the prior year that it was time for the new cable revision, and it was usually true.

After Rev G they kept releasing new cable sets but stopped upping the revision number, it was all Rev G after that. Don't think it's ribbons in this part of this amp though.

[wavley]

New Fenders have a TERRIBLE problem with solder cracks.  I would also suspect the ribbon cables coming from the controls to the board. 

I've heard a lot about cracking solder joints in the new Fender amps. That's another good possibility. Ribbon cables are less likely to fail, but it's possible that it might have a dodgy connection in it.

The only reason that I suspect the ribbon cables is because they are the pierce the insulation type cables.  The Mackie 1604 mixer makes me suspect ribbons more than I should sometimes, they were on like Rev. G or H when I left the shop four years ago.  It was the joke around the shop when somebody brought a 1604 in that had been in the prior year that it was time for the new cable revision, and it was usually true.

After Rev G they kept releasing new cable sets but stopped upping the revision number, it was all Rev G after that. Don't think it's ribbons in this part of this amp though.

Yeah, I couldn't remember exactly what Rev they were on because it was a few years ago.  I was just throwing the ribbon out there because there is a ribbon for the reverb control between the control board and the main board.

[Paul Marossy]

  I was just throwing the ribbon out there because there is a ribbon for the reverb control between the control board and the main board.

Yeah, seems like it could be the source of the problem to me.

[mikemaddux]

got it back.........finally.....

bad reverb transformer

[MikeH]

I'm taking all bets!!  3:1 on a solder joint gone bad, 7:2 on a bad component, 15:1 on a bad reverb OT, 20:1 on a bad reverb tank.  Place your bets! Place your bets!





*Note: I am not actually taking any bets

Damn! 15 to 1 is a pretty good payout...

At least it was one of the "cheaper" irons.

[Paul Marossy]

got it back.........finally.....

bad reverb transformer

Huh. Good to know for future reference.

[Quackzed]

nice! glad to hear you got it fixed. in my opinion, the twin reverb is 'king of the springs'
it doesnt get much more sweet and drippy than a twin with the reverb around 4-5. which is about as far as i dare go. 
now go play some dick dale and some ventures tunes.

[mikemaddux]

Ya, I dont know why it took him so long to find out what the problem was....But hey, its good to know where the typical issues pop up at.

The Twin Reverb is truly the "king of the springs"!  lol

[Paul Marossy]

Viva King Of Springs! 

[wavley]

If you REALLY want to heat that thing up, I've got some capacitors filled with Dragon's Blood that I can sell you.

[mikemaddux]

If you REALLY want to heat that thing up, I've got some capacitors filled with Dragon's Blood that I can sell you.

??   

[Quackzed]

I have a TwinReverb II. it has an fx loop with a gain control, so if i patch the effects in: to the effects out: i can crank up the fx loop gain and drive the reverb section, which comes right after the loop. kind of a reveb boost, and it really gets swampy even at low reverb level with the loop turned up a bit, from there it gets over the top fast. 

[Davefx]

I just happen to have a '65 Twin RI on my bench for repair.  It too had a reverb problem, lucky it was a broken wire going to the output transducer in the tank. But your experience gave me some education if I ever come across a similar situation..  Those things must be under a lot of stress, that or they're made crappy.. You wouldn't think they would have that much electrical stress but I'm not a wiz on reverb circuits.