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Post subject: Re: Some TLC for my 1965 6G15 Reverb Unit
Posted: Sat Mar 25, 2017 8:11 am
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OK so the Orange Drops have arrived, 0.1uF / 600V. The new super-fangled Rectifier diodes will be in my mailbox this afternoon. An interesting day ahead!

Today's Stoopid Question: I notice there is no polarity marking at all on the Orange Drop caps and both leads are the same length, no indication of polarity at all... does polarity not matter with these or is it time to break out the Ouija board?
:?: :mrgreen:


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Post subject: Re: Some TLC for my 1965 6G15 Reverb Unit
Posted: Sat Mar 25, 2017 2:30 pm
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Well, good news then bad news...

The Orange Drop caps went in and sound was somewhat improved, although still very harsh, brittle and "squanky" on the treble side - entirely hard on the ears with the bridge pickup, much more liveable with the neck pickup. Makes me really wonder if I just have a whole bunch of bad tubes at this point...

Before pausing to take voltage readings I decided to go ahead and swap out the filter caps since I was on a roll, and also had the UF4007 rectifier diodes and decided to put them in too.

That's where apparently things took a wrong turn. It was easy enough, I used some small copper clips on the rectifier diodes to act as heat sinks.

However now. although I get a pilot light, the unit is pretty dead. The tubes aren't warming up, a see about 68 volts DC at the first rectifier and then not much past that. And worse, I heard some sizzling sounds while it was on, coming from the transformer. I turned it off but even coming back a few minutes later the transformer was pretty hot to the touch.

Not sure where I screwed up, maybe I can work backwards and out the old diodes back in. I should have been more careful just changing things one at a time and measuring, but I got overconfident.

Pics below... anyone see anything blatantly wrong?

Image

Image

Yeah, I know this didn't come out very pretty....

Image


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Post subject: Re: Some TLC for my 1965 6G15 Reverb Unit
Posted: Sat Mar 25, 2017 3:46 pm
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Well are the polarity of those diodes correct(I've never worked w/ them), doesn't the banded side = the +.
Some of your soldier work is possibly bad, needs a touch up(reheat/flow) or is a little light/heavy in areas.
Are you using a good electrical type rosin core 60%tin/40%lead solder? a little Silver % doesn't hurt as long as you get good flow. Seems to me your getting cold flow joints. Remove the globs w/ braided copper or a sucker and re-do.
Those PSU caps are 8 years old? I would have returned them if purchased new recently.


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Post subject: Re: Some TLC for my 1965 6G15 Reverb Unit
Posted: Sat Mar 25, 2017 6:42 pm
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Eric, the diodes appear to be put in backwards. Check my photo of board, on 4th page of thread.

Image


Versus your bridge:

http://img.photobucket.com/albums/v148/ ... g8uqqf.jpg

As for the tone... give the OD a bit more time to break in --- a few playing hours. If it's still brittle, try PIO caps. Do you have any 12AT7 you can replace for the input tube?


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Post subject: Re: Some TLC for my 1965 6G15 Reverb Unit
Posted: Sat Mar 25, 2017 6:54 pm
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BTW... I remove the two screws holding down the top fiber board where the diodes are located. Remove old part. Clean hole. Place new parts in, adjust lengths... then solder. To get short straight components.

Vintage Jupiter Yellow polyester caps maybe what you need.

http://www.partsconnexion.com/capacitor ... _tone.html


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Post subject: Re: Some TLC for my 1965 6G15 Reverb Unit
Posted: Sat Mar 25, 2017 7:08 pm
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:oops: OK, THAT was embarrassing.... yeah, things work MUCH better with those diodes installed the right way!!! Jeeeeez.... thanks guys!

Never installed diodes before obviously and misread the marking info I found on the interwebs. What a moron. And now, I know a much better way to do it thanks to your last post. Thank you!

Things sound MUCH better now. I spent quite a while playing through it and it's still apart on the bench. Any remaining brittleness in tone seems to be coming from the little old Fender Bullet amp I have out by my workbench. But this is ready to be heard through a proper amp now. Tomorrow I will get the 1M grid-to-ground resistor mod installed on pin 2 of the output tube per the other thread here.

I have a an RCA 12AT7 already (in the input tube which is specified as 12AT7, right?) and a JJ 5751 in the 7025 position. I do definitely feel that any further refinements from this point forward are just going to be a matter of experimenting with the right tube combos. What I don't have is a proper 7025 tube, and I need to go re-read all your tube recommendations and do some ordering. Oh OK maybe I'll play with some of those other caps too if need be, I have the bug now to keep wanting to work on this. Specially when you keep posting links to cool parts, dangit! :lol:

I also need to get the original reverb pan connected back up and see how that sounds but that will happen when I get things cleaned up, it needs a good solid cleaning on the outside, tolex and faceplate, which will be a pleasure to do now that things are running right. DeoxIT GN5 did a GREAT job cleaning up the pots, no scratchiness at all now, nice and smoooooth and I gave the tube sockets and plugs a good going-over as well.

Thanks for the patience, help and guidance, guys. Really appreciate it and things are lookin'/soundin' good!

:mrgreen:


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Post subject: Re: Some TLC for my 1965 6G15 Reverb Unit
Posted: Sat Mar 25, 2017 7:18 pm
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[quote]Eric, the diodes appear to be put in backwards. Check my photo of board, on 4th page of thread./quote]
Yes that's what I did after I posted, I copied your photo and his photo to my photo viewer to compare. Its easier for me to see @ 200% zoom.

As far as the tone caps, I gotta say I'm really digging the SoZo's in my Strat in place of OD's. They seem to mellow out the spikey treble tones and are relatively inexpensive and cheap compared to Jupiter or PIO caps.
I realize we may be talking apples and oranges in this application though.


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Post subject: Re: Some TLC for my 1965 6G15 Reverb Unit
Posted: Sat Mar 25, 2017 8:53 pm
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On another board, I've read about a couple of instances where Sozo caps prematurely failed in in high DC voltage situations (leaked DC). So, for more vintage tone --- I've been using Jupiter Vintage Yellow or Red labeled caps.

Of course, I have a stash of Jupiter and Russian mil spec PIO caps. They have been stone cold reliable. But get highest voltage rating possible.

Glad you got your Unit working. And the diodes were ok. UF are pretty tough cookies. :)


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Post subject: Re: Some TLC for my 1965 6G15 Reverb Unit
Posted: Sat Mar 25, 2017 9:19 pm
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As for my experience with tubes with my Reverb Unit...

1.) You need a strong, quiet 12AX7 (7025). My all times favorites are the Raytheon black place mil spec 12AX7A. And the BP RCA 7025. Gray plate of either are also very good.

2.) The 12AT7 input tube doesn't need to be a special mil spec tube. A nice, strong (black or gray plate) Sylvania, GE, or RCA will be fine. As new tubes go... The Gold Lion 12AT7 is a very good tube.

:mrgreen:


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Post subject: Re: Some TLC for my 1965 6G15 Reverb Unit
Posted: Sat Mar 25, 2017 11:35 pm
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Stoopy wrote:
:oops: OK, THAT was embarrassing.... yeah, things work MUCH better with those diodes installed the right way!!! Jeeeeez.... thanks guys!

Never installed diodes before obviously and misread the marking info I found on the interwebs. What a moron. And now, I know a much better way to do it thanks to your last post. Thank you!

Things sound MUCH better now. I spent quite a while playing through it and it's still apart on the bench. Any remaining brittleness in tone seems to be coming from the little old Fender Bullet amp I have out by my workbench. But this is ready to be heard through a proper amp now. Tomorrow I will get the 1M grid-to-ground resistor mod installed on pin 2 of the output tube per the other thread here.

I have a an RCA 12AT7 already (in the input tube which is specified as 12AT7, right?) and a JJ 5751 in the 7025 position. I do definitely feel that any further refinements from this point forward are just going to be a matter of experimenting with the right tube combos. What I don't have is a proper 7025 tube, and I need to go re-read all your tube recommendations and do some ordering. Oh OK maybe I'll play with some of those other caps too if need be, I have the bug now to keep wanting to work on this. Specially when you keep posting links to cool parts, dangit! :lol:

I also need to get the original reverb pan connected back up and see how that sounds but that will happen when I get things cleaned up, it needs a good solid cleaning on the outside, tolex and faceplate, which will be a pleasure to do now that things are running right. DeoxIT GN5 did a GREAT job cleaning up the pots, no scratchiness at all now, nice and smoooooth and I gave the tube sockets and plugs a good going-over as well.

Thanks for the patience, help and guidance, guys. Really appreciate it and things are lookin'/soundin' good!

:mrgreen:


Do you have the original footswitch for this tank?

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Some TLC for my 1965 6G15 Reverb Unit
Posted: Sun Mar 26, 2017 12:36 pm
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Retroverbial wrote:
Do you have the original footswitch for this tank?
Arjay


No sir. I found this tank in a dusty dark shop in San Berdoo that sold mostly used old amps. It was sitting in a pile in the corner, I do remember the guy in the shop said something about a cap job maybe being needed but the price was right and it powered up and played so I went with it. I think the guy was surprised anyone was looking for one of these, it being the early 80's at that point. Using it in our little surf band, I never had much need to turn the reverb off. 8)

I've seen the repop foot switches but they seem to use RCA jacks these days.


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Post subject: Re: Some TLC for my 1965 6G15 Reverb Unit
Posted: Sun Mar 26, 2017 1:45 pm
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Now for the Happy Ending... :lol:

After putting in the recommended 1M-Ohm 1/2-Watt resistor on pin 2 of the 7025 socket to the ground plug of the footswitch (visible in pic below) and running one last functional test, I spent some time cleaning up the case, gently scrubbing the tolex with some warm soap and water (S p i c N'Span) several times to remove ages of dirt and dust. It was a little tempting to put some Armor All on it but, ya know what, I like the patina look right now.

Putting everything back together gave an opportunity to plug the original Gibbs tank back in and it sounds GREAT. You can just feel the salt water hitting your face. Breaking in these OD caps is gonna be a hoot!

As a last touch I screwed on a repop Fender badge on the front. The screw holes lined up perfectly with the decades-old unused screw holes barely visible in the grill cloth, and the screws were a perfect fit - I don't feel one bit bad about having a "new" piece on a vintage unit. So she can now wear her new badge proudly in all her glory. :P

I'm probably gonna experiment with some of those other caps like the Jupiters way down the road, but in the short term I'm definitely gonna buy a new set of tubes based on recommendations above, and report back. And I'll definitely keep hanging out here, I think I have the bug to work on this stuff more now (just gotta pay better attention to schematics and markings, D'oh!).

Steve/BMW2002Ti, Arjay/Retroverbial and sfceric64 - I cannot thank you enough for helping me get this far with this project. This far exceeded expectations, and there's just no way I would have been able to do it without you. This unit has come a long way and is in way better shape than even 30-some years ago.

My greatest thanks!

-Erich

Image

Image

Image
8) 8) 8) 8) 8)


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Post subject: Re: Some TLC for my 1965 6G15 Reverb Unit
Posted: Sun Mar 26, 2017 2:31 pm
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Outstanding!

You do know that you owe us a drink, right......?

:wink:

Arjay (who hankers for a single-malt)

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Some TLC for my 1965 6G15 Reverb Unit
Posted: Sun Mar 26, 2017 3:18 pm
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Retroverbial wrote:
Outstanding!

You do know that you owe us a drink, right......?

:wink:

Arjay (who hankers for a single-malt)


Yes I do! I almost put it in my post above so will say so now - feel free to PM me your favorite libation and a ship-to address! :mrgreen:
8)


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Post subject: Re: Some TLC for my 1965 6G15 Reverb Unit
Posted: Sun Mar 26, 2017 4:06 pm
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Good to hear "happy endings." :)

I think you are going to like the OD caps in the unit --- as the months go by. This thing is wicked plugged into a tube driven oscillator-vibrato amps. Like BF or SF Vibro-Champ or Princeton amps.

Thanks, for the kudos. Have fun! Keep us posted.


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