Restoring a blackface 6G15 Fender Reverb Unit

[bram9206]

Some weeks ago I bought this old Fender Reverb unit. When it arrived I was surprised to see that it was in very bad shape. Woodworms had eaten away huge pieces of wood underneath the tolex. I debated building a new cabinet for the reverb unit, but in the end I decided to restore the original cabinet and keep the original tolex.
I also needed to replace the original 110V US power transformer with a 230V European transformer.
Now here's, just for the fun of it, a photo report of the restoration of this wonderful peacy of Fender history.

Starting with the tolex coming loose because of the woodworm-damage underneath.

So I took off all the tolex in order to clean it and restore the wooden cabinet.

Then I treated the cabinet with an anti-woodworm product.

Cleaning both sides of the tolex to get rid of the glue and other dirt. I wanted to keep the original tolex because it was still in acceptable condition and it adds to the authentic vibe of the unit.

Then it was time for the biggest part of the work: restoring the wooden cabinet with wood filler. Especially the rounded corners where a challenge, because they were almost gone so I had to kind of 'rebuild' the wood with wood filler as if it was clay. I had to do this in different stages, wait for every layer to get dry and sand with sandpaper in between the stages. Quite time-consuming...

Finished, all sanded and now ready to glue on the original and cleaned tolex! Check out the corners, quite happy with the results.

After gluing the tolex the unit looks wonderful and still has the authentic looks! Really happy with it!

The original 110V US power transformer.

Now with a TAD power 230V EU transformer. These transformers don't have a central tap, so I had to make an artificial central tap by soldering two 100R resistors from the filament wires to ground. Also, this original unit still uses a half-wave rectifier, so there's only one HV lead that goes to the rectifier, the other HV lead goes to ground.

Still housing all the original components!

And the best thing is, it works! Sounds wonderful and very quiet.

 

[dmp]

Looks very nice - good restoration. Nice you were able to save the original cabinet.
Looks like a very early one, late 1964.
Funny there's the one astron cap, which were typically used earlier. 

 

[pH]

Great job, I did a similar restoration years ago to a Magnatone Troubadour amp that was in pieces. Wish I had photo documented it.

Now get rid of those dried out electrolytics! 

Paul

 

[bram9206]

Yeah, I know those electrolytics should be replaced, but since the unit still works great (no hum, noise or whatsoever) I would like to keep it original. Maybe I'll change the filter caps, always worth doing that when they are 50 years old (still works though). Is it true that when one day all of a sudden they go bad they can really damage the circuit?

 

[andyfromdenver]

Yeah, I know those electrolytics should be replaced, but since the unit still works great (no hum, noise or whatsoever) I would like to keep it original. Maybe I'll change the filter caps, always worth doing that when they are 50 years old (still works though). Is it true that when one day all of a sudden they go bad they can really damage the circuit?

No expert, but have apprenticed for a tech and build amps.
I don't believe it will damage the circuit.  Just compromise the intended sound/hum/frequencies.

You really get the labor of love reward for keeping that wood! 

If you are gonna keep it forever and ever, just change the electrolytics and maybe put a silver mica and poly on the tone pot, imo.
I think most buyers would appreciate the service too, especially having to reveal the extensive work done on the cab.  Sadly, it is no longer a collectible imo and should just be brought to peak performance and enjoyed. My 2 cents

*and ps, by saying "I don't believe" read as seek further opinions *
*edit:  I was doing some reading on elytic failures.  Seems more likely that an oldie with fail open, and might not ruin other components, but if it shorted, that could be bad.  Probably don't want to risk that.  There are some guys who stuff new caps in the old shells.  I'd only take issue with that if you didn't reveal it at sale etc.  if you do replace them, you could always keep em in a Baggie for nostalgia/ completeness* crap up to 4 cents now
Also, I don't think I said, but really good job on the restore

 

[lassoharp]

Yeah, I know those electrolytics should be replaced, but since the unit still works great (no hum, noise or whatsoever) I would like to keep it original. Maybe I'll change the filter caps, always worth doing that when they are 50 years old (still works though). Is it true that when one day all of a sudden they go bad they can really damage the circuit?

Provided you have the correct fuse the worst would be a blown fuse.  The electrolytics in the PS filter will either lose capacitance and leak hum or go dead short and blow the fuse.  And, they eventually will fail at some point.  The 250uf cathode bypass on the 12ax7 gain recovery could contribute hum if it gets really weak.  Ignore the odd voltage ratings and just use a 470uf/25V to replace.

You are lucky to have a quiet one that interfaces with other amps without buzz.  I've built one succesful clone and have just completed the second one.  The first one was hum/buzz free but the second is not and is proving very difficult to correct.  Many people wind up using a transformer iso box to break ground loops or even resort to lifting the AC ground which I would not recommend for safety reasons.

Very nice work on the restoration!

 

[mjrippe]

Very nice job!  My one concern is that the edges might crumble if they get hit.  The Tolex should contain things, but regular wood filler on edges is not super strong.  When I was working with a guy who restored jukeboxes we would use Bondo auto body filler for repairs like this.  Just for future reference