Got the TV Tweed Pro all working

[chopstuck]

This is about my old Tweed pro I got as a project 20 oe more years ago.

OK, got the MM OT mounted as simply as possible. Was going to do a bracket and bent legs and angles and and....... never mind.

I got it all wired up and plugged into my limiter.
Power on
Nothing.
Then replaced power switch with new one, - POWER !

We got guitar type noise after letting the caps form/charge for a few minutes.

I then put full voltage to it and ... no smoke. Sounded like angry bees on a snare drum.

I had between 3 and 6 Vdc on my 6L6 grids. Replaced those two coupling caps with some salvaged Sprague blackies and got it down to about 10- 20mv. All I had were 400v rating, seemed ok there as the voltages were under 300.
I had 12 volts ac at my first node. I replaced the last paper E-lytic and got that number down to 6 volts.
Amp is pretty quiet but got a little ghosting going on.

Sounded better and output section current draw was down 16ma to 48ma/ 6l6 pair. Seems like 27v on the 260 ohm Kr is a lot as the cap was only rated at 25vdc. Hmm

Still has a bunch of rude non-musical distortion. I figure if those ugly wax dipped cap were bad in that position, the others probably are too.

I should say I have had this amp for over 20 years and bought it in pieces from the Chicago store in Tucson.
I found it in a few different places, the chassis in the repair pile and the cab in a different aisle. I was stoked as the serial numbers matched !
I bought three Tweed Pros that day as well as a Gibson GA 55v. Later traded it to Mark Sampson. I wonder if he got it working in the Pre- internet world.
Anyway,it was dead when I found it all that time ago, even deader now.

I replaced each cap and listened for an improvement until all of them were deemed "crap". The last one was the worst, it was the poly tone cap.
It made a big difference.
All pieces were subbed with old molded parts.

I now have a pretty good sounding amp. Seems like the more I play it this weekend, the better it sounds. Psycho-acoustic ....? maybe.
It's not perfect yet. I still have to do a little tube tweaking, I may build a clone to mess with. Funny that a simple amp that can sound so good.

Before you say anything about being messy, I'm not done redressing the leads and cleaning up the cold joints. These big amps with the FC speakers have to lay face down and my bench is too cluttered yet.
Was unmolested before but now it's working. Looks OK to me- sorta period correct .

Overall I wish I would have done this sooner.

[Reeltarded]

Excellent! Looks great!

[rp]

Funny that a simple amp that can sound so good.

You have found wisdom, grasshopper.

[Structo]

I don't think it looks bad at all.

I think it looks great!

Did you check the resistors for drift?

I worked on a amp with those type of carbon comp resistors and many that were subject to high voltage had drifted up substantially.

[M Fowler]

I agree I love seeing these old amps get new life.

You can always do improvements as needed later.

Mark

[chopstuck]

Yes I checked all the resistors and found them to be at about 20% drift,
The 5 megs were 4 megs and the 250k were all around 275 -295K.
Is 5vac acceptable at the first node ?

[Structo]

5vac on the heater?

[chopstuck]

No I have 5vac ripple on my 388v dc first node.

AND....... today I turned the amp on.

BRAAAAAAAAAT !

Sounded like a V2 pulse jet. like this one:

http://www.youtube.com/watch?v=teQXaqeEnl8

Since it sounds like 60 hz, I may still have some bad PS caps me thinks.

OR
one of my salvage pieces is bad.

[rp]

Your ps caps are from '95 - might be bad. You should have started them up real slow with a variac, 50% for several hours then 10V/hr, or a DBL changing wattage every few hrs. At this point I would just replace all for with fresh and be done till 2032.

That'll be a sweat amp in the end. Nice that you kept the field coil.

How do I combine a DIY pulse jet with a potato cannon?

[chopstuck]

RP, I like the look of the old Atoms but I realize they weren't great caps to start with.
Is there a way to put new small caps in the old shells without too much cancerous goo exposure ?

[rp]

I tried it once, but was a halfhearted effort. Not as easy as it looked. You need to unroll the edge and then roll it back up as a penny roll, but 60 year old machined paper doesn't want to do that. Maybe try for a clean cut 1/2" in from the edge around the circumfrence with a nice new exacto blade, or one length-wise cut and hide the cut side towards the board. You then need to hacksaw the can and pull the innards out and that's unpleasant, and drill the ends. Put it all back together so it doesn't looked hacked by a reptile. There is no space btwn the paper and the can either for tape or anything. The can must be closed up flush like new. If the paper had unrolled nice I would have spent more time on it. Either cut just the metal ends off the can, or tossed the can and made some new faux slugs for the ends and filled the cardboard tubes with something for support, something removable in the future, a pill jar or plastic tube or foam.

My thought now is a length-wise cut on one side, cut off just the end caps, put the new smaller cap inside with some packing and go that route.

Not sure if it's PCB in the old ones and cancerous, mutagenic, toxic or whatever. Probably no big deal if you use gloves, don't lick your fingers, wash up and clean up nice. Maybe best to not do if there's babies or pregnant women around. Anyway my unrolling and hacksawing came out ugly enough that I gave up. It was long ago and I wasn't as interested in a perfect looking restoration as I would be now. If you have extra caps practice on those, or try and get some old ones from members here or ebay.

Be great if someone whose done it well could pass on the knowledge. Maybe there's already a Youtube vid?

At this point my guess is that as amps go from vintage to antiques non working originals will be worth more than restored ones. So you have to decide to keep the bad but orig parts in a ziplock for a future non working restoration, or mess with it as is your inclination as a TAG tinkerer. As it's already re-tolexed I say tinker away.