Advice on refurbishing 5E9a Tremolux?

[jackg]

Been lurking for a while ... great forum! First post ... I intend to refurb a 5E9a Tremolux that's been through a house fire. Some smoke evidence, no water damage apparently. I'll post separately about the cabinet. What I'm looking at is capacitors .. attached photos of the interior. We're getting some sputtering and crackling once it's well warmed up .. though it passes signal fine and doesn't sound bad overall. In photo 1 (chassisright) the three 16uF caps wereapparently replaced a while back - replace again, yes? In photo 2 (chassisleft) .. green arrows show a couple of orange-drop looking caps, and the red line encloses 5 others, either coupling caps or parts of the tremolo. These look older .. originals?
Should I do a wholesale replace? Or get out the meter and check for leakage and leave any that seem good?
Thanks.

[jackg]

Second question ...

Related to the first question .. the "chassisright" photo has a green arrow to a 10K resistor, which was apparently was put in to replace a 2500 ohm one - this resistor was the first in the power supply chain. Attached is a section of the schematic - red arrow to the R in question. The schematic calls for 290 V at pt. B, while this amp measures 253V there. That much drop is sorta reasonably consistent with the increase in that resistor. Point B feeds the tremolo, the PI, and the input section. If I do the recapping from post 1, it seems reasonable to me to take this resistor back to the 2500 ohm that was original ..yes?
Thanks again.

[tubeswell]

Hi Jack

Good luck finding those old caps. In terms of circuit values, it'd be good to put everything back to 'stock' at first and see how it goes. Check all the coupling caps for leakage

Check all the voltages (heaters, rectifier, filter caps, plates, screens, grids and cathodes)

Here is a gutshot and backshot of a 5E9A (if that's any help)

[bob p]

Bhat I'm looking at is capacitors .. attached photos of the interior. We're getting some sputtering and crackling once it's well warmed up .. though it passes signal fine and doesn't sound bad overall. In photo 1 (chassisright) the three 16uF caps wereapparently replaced a while back - replace again, yes?

None of those PSU caps look original. They look like something that somebody cobbled into place when the amp was being serviced. I would not hesitate to replace all of the 'lytics.

Is there any specific reason you've got an arrow pointing to the domino cap at the bottom of the photo? Its not original either.

the only cap that looks original is the red one that's dead center at the bottom of the photo.

[bob p]

In photo 2 (chassisleft) .. green arrows show a couple of orange-drop looking caps, and the red line encloses 5 others, either coupling caps or parts of the tremolo. These look older .. originals?
Should I do a wholesale replace? Or get out the meter and check for leakage and leave any that seem good?
Thanks.

No, those orange drops aren't originals and there's nothing special about them. I don't think that any of these red caps are original either. I think that their body styles are later than the manufacturing date of the amp, that the lead dress looks very shoddy and non-factory, and the solder joints look reworked. I'd say that they're the result of a lame service job that was performed a while ago.

Red caps 3 and 4 could be very old, but I don't think they're original 1950s. Red caps 1,2 and 5 definitely don't look original to me. To me they look like pressed film foil caps with radial leads that have been bent axially. Its hard to be certain from the photo. The solder joints also look reworked, suggesting replacement. I suppose that if they're not pressed caps, then maybe they could be rolled caps that were just deformed by the heat.

I wouldn't worry too much about keeping these caps. My first priority would be preserving the integrity of the circuit, not preserving individual caps on an amp that's been through a fire. I wouldn't hesitate to pull them all out and replace them. But I wouldn't necessarily throw the original caps away right away.

Interestingly, all of those caps look like they have soot on them. Is that just smoke damage, or did the amp get hot enough to damage them? Some of them also look like they're deformed. If that's the case then you can't trust their integrity and that's another reason to pull them all out.

I'd replace all the caps on an amp that's been in a fire, especially if you're hearing symptoms of cap failure. Caps are cheap and time is money. I'd also test all of the carbon comp resistors for tolerance, and I'd replace anything that is out of spec.

My main concern would be that the transformers' insulation and the speaker weren't damaged. And the cabinet. Those are the only important original parts that I'd worry about after a fire.

If it were my amp, I'd make a case for how bad the amp sounds and I'd ask the insurance to total it. I'd also point them toward the cosmetic/smoke damage to the tweed. Then I'd exercise salvage rights to buy it back at 20% of the settlement price. Then I'd start the restoration project.

[jackg]

Thanks ...

I forgot about marking the domino cap - I was curious about its originality.

bob p wrote: "If it were my amp, I'd make a case for how bad the amp sounds and I'd ask the insurance to total it." - That's been done - they did so and anted up for a '60 5G9 replacement, and left the old one with us (this is my brother's amp...). So there's nothing to lose on the old one, monetarily at least.

The darkening on the caps is smoke/soot. It doesn't appear to have gotten hot enough to soften anything.

The cabinet survived intact. It has no tweed left other than the back panels - a previous owner apparently removed it, stained the wood, and then varnished it, pre-fire. I intend to re-tweed it as part of this project. The speaker's been replaced as well, and so will likely be replaced again .. P12Q seems the appropriate choice, yes?

Thanks for the comments - looks like it's time to replace all the caps, any of the resistors that don't spec out, and see to some basic cleaning where I can.

[Bruce / Mission Amps]

The only capacitors that are original are the ones on the tone control... that includes the E caps.

[jackg]

Update ... with pics

Just thought I'd update on the results. New caps throughout, mostly new resistors, and new tweed job for the cabinet. All the voltages measure right, everything runs cool and serene, and it sounds GREAT, as expected. We've got a late 50's reconed P12Q on the way, and I'm looking forward to it being totally done and back making good sounds. Thanks for the advice and recommendations.
Here are the new chassis interior, and the top panel

[jackg]

And a couple more pics

The front and back. Had to make new upper and lower panels for the back, as the old ones were the only parts of the cabinet that still had old tweed intact (though badly smoke damaged) and my brother wanted to keep them.