Rehab for a 61 Concert

[dreric]

Hi guys!

I just scored a cabinet for my 1961 concert so after a loooong time on the shelf it's time for a little re-hab. Despite missing it's cabinet the amp is pretty clean. I'll detail what I can see has been done by previous techs and my plans, but please feel free to make suggestions:

1. Replace the filter caps and dropping resistors. Two have already been replace but I think a fresh set is in order.

2. Replace the Vibrato channels volume pot. Should be 1 meg someone put a 500K in there.

3. Remove the death cap and replace the power switch with a proper one. Also someone added a convenience outlet in the tube cut out, that's got to go.

4. The bias was redone at one point and the 3uf an 2uf caps were replaced with 10uf. I'm thinking of taking it back to stock or I can keep the 10uf, suggestions?

5. Replace the electrolytic on the board.

I like pictures so I took a bunch:

[dreric]

More:

[dreric]

all done:

[Firestorm]

That is super cool! It looks like the ATOM filters are replacements as well: aren't they dated Dec. 1967? Same goes for the 2uF on the board. No way that needs to be 450V. My schematics show 8uF in the bias supply, so 10s aren't wrong, but I'd replace all the electros. I'll bet the coupling caps are all still fine.

[dreric]

Just brought it up on the variac to make sure everything works before I do the caps.

Channel one is weak about 1/2 volume

Channel two is awesome, I had forgotten how cool the vibrato is.

[overtone]

Eric, it is great to see this coming back to life.

Brownfaces are really rare over here. I have never heard one of these but have a similar condition Concert chassis waiting in the wings like yours did. Only it is the next generation, dates '64. Your thread is kicking me up the backside to get a move on!

tony

[Stevem]

With the way that amp looks with its surface rust and loss of a lot of the chassis zinc plating I would be sure to run a thin strip of card board soaked with contact cleaner through all the 4 input jack muting contacts on the jacks and then do the same with some WD 40 after running a strip of folded over 400 grit wet or dry sand paper through them first.

[dreric]

With the way that amp looks with its surface rust and loss of a lot of the chassis zinc plating I would be sure to run a thin strip of card board soaked with contact cleaner through all the 4 input jack muting contacts on the jacks and then do the same with some WD 40 after running a strip of folded over 400 grit wet or dry sand paper through them first.

Sounds smart! any other tips?

[martin manning]

I will disagree with the suggestion to use abrasive paper. It will cut through the plating, and then the base metal will quickly oxidize. If there are problems with the contacts, try contact cleaner on paper. If that doesn't work replace the jack.

[rp]

Fantastic! Don't replace anything stock you don't have too, make the rest stock, 10uf bis caps are fine, but find real tubes across the board. Find the dough for a really nice hide glue repro cab, it matters, you can hear it when you rap on them. $peakers?

A properly working Concert is a divine experience. A mighty amp. Way jealous.

[billyz]

Fantastic! Don't replace anything stock you don't have too, make the rest stock, 10uf bis caps are fine, but find real tubes across the board. Find the dough for a really nice hide glue repro cab, it matters, you can hear it when you rap on them. $peakers?

A properly working Concert is a divine experience. A mighty amp. Way jealous.

I agree with rp. Hide glue solid pine is the way. Mergili innovations can make you one that is vintage correct in every aspect possible.

[Stevem]

pulling a strip of 400 grit thru the switch contacks will not revove any plating, I have been doing this for 40 plus years and have never had a issue even on the amps I have gome back to me for re-tubing and caps in a 30 year span.

[billyz]

On severely corroded jacks I have use rolled up 600 grit with deoxit and pulled a folded strip through the shorting contact. Works.
But only if needed. First I would try deoxit and a qtip and a drop on the shorting contact. Probably all you need. I also loosen the jack and put a drop between the chassis and jack, of course retighten all the jacks and pots.

[Firestorm]

I have an old sheet of something called "crocus cloth" which is a fabric-backed abrasive used for soft metal polishing. Something like 1500-2000 grit. Removes dirt and oxidation nicely, but you would have to work very hard to remove much of the plating.

[Gibsonman63]

I use a burnishing tool, gently. If they are too far gone, I just replace them.