Other Amps

What happens to an amp that isn’t used for years?

26

Your concern for my safety is gratifying, but I assure you it is no greater than mine.

I’m not about to be a dead hero here, I love my wife way too much to make her a widow. I’ve been very lucky in the past and dodged many (unknown) bullets so please don’t think I’m about to do anything stupid based on your well intentioned advice. I’ll be very careful.

As I said I will pull the chassis to keep an eye on things, but I’ll not do anything stupid.

Again, your help is very welcome and I’m grateful for it.

27

If in any case you are happy to pull the chasis it is the best way to do it as you can see where an arcover starts. You then know exactly where and how to fix.

I am sorry if I sounded offensive. I know you are not an idiot. I get upset also if someone comes with all the warnings and assumptions of incapability. But, it has to be put that way, hope you understand.

I am glad to help you every step of the way and save you a possible 1000+USD.

28

No offence taken, I’m truly grateful for your concern. Best to assume total ineptitude rather than to assume any degree of competence, I’m totally on-board with that.

29

This is the variac I bought:

Link

Stage 1 - confirm pass-thru earth: COMPLETE, earth pin on output has continuity with earth pin on input.

Stage 2 - check output conforms to stated output: COMPLETE. printed legend is next to useless, but output is consistently 1-2v below digital read-out right up to 250v.

Will report back later once I’ve done the ramp-up.

30

Sounds good. Please remember to constrain variac at 240V. Even now after years I still nudge it past.. not good. Thats a very nice variac. Yep printed legend is always useless. They always print linear, but reality works slightly nonlinear with a variac. At least you have a constant offset. I have to deal with cumulative error on some of mine! I wont be available for next 6 hours, and will check again after that.

32

OK, time for an update. I started with the Showman as it was already accessible and has been sitting in the living room acclimatising for a few months. Here she is.

33

Firstly I inspected it closely for any signs of rodent or spider activity and it was all clean. I may have vacuumed it out when I retrieved it from the shed back in the early summer, but as you can see it's pretty clean.

35

Then I took out all the valves to make the chassis removal easier and popped the chassis out. This is the first time it's been out of its case in many years, maybe even since '95 when I did the rewire. There is absolutely no evidence of spiders or vermin, not even any webs. Wires all look clean with no obvious signs of oxidisation.

41

I followed Retnev's instructions to the letter and experienced no problems at all. No unusual smell, no arcing, no smoke, nothing. Some mains hum did creep in at around 150v, but I don't think the variac is the best of quality and it may have been a bit of interference from that as it was sitting very close to the amp (once it's all back together and plugged in without the variac if the hum is still there I'll take it to my guy to check the caps out).

Once it'd been at 240v for 5 minutes or so I ramped it back down, left it to cool a little then put it back in its case. I'm now about half way through the final hour that gets it nice and warm and dry.

Retnev, thanks once again for your invaluable help. I feel very confident to tackle the other two.

42

Just popped back at to the shed after an hour and all looks well. The mains hum does seem a little louder than I remember, even without the variac in circuit, but I may have still had the open-ended cable* in the input so that will have likely exacerbated it. Once I have it bolted back in and running through its proper cab I'll know for sure. I may get it looked at professionally anyway, but at least it's out of hibernation.

*I say cable, but it was actually an Xvive wireless - like I said, I'm all about safety...

43

The bypass caps are old. Do the filter caps look like this?

44

I don't see anything in there that looks like that.

45

Wait a sec, are they under a cover on the transformer side? If so I didn't remove that cover.

46

Yep, in the doghouse.

47

As far as I'm aware 99% of the components are original so yes, they probably look just like that.

A little history about the amp: I bought it in the late 80's or early 90's. The story it came with is that it was in Vietnam during the war and got bombed (the chassis is still very mis-shapen as you can see from the back panel, but has been straightened enough to go back into its case). The guy I bought it off of took it to legendary ex-Vox tech Alan Pyne in Dartford, Kent (locals will know of Alan; he worked for Vox and took over their premises to run an amp repair shop when they sold out). Anyhoo, between Alan and Dave they removed the O/T and replaced it with a Marshall one, and replaced the 6L6s for EL34s. They also bypassed (cut out?) the magic eye that controls the tremolo. Dave then built it into a combo cab he'd made and coupled it with a 1x15 Gauss speaker so he could use it as a bass amp. That's how it came to me.

I used it for a bit, but was never happy with the combo cab as it was open backed. I took the amp out and after scouring the early internet found not only the schematic (not really any good to me), but also the hand-drawn wiring layout. Now this I could use. I then methodically replaced every wire as per the original drawing. By sheer fluke of luck I managed to find not only a genuine period correct O/T, I also managed to track down a magic eye for the tremolo, so after rescuing the original case from Dave I was good to go.

I did upwards of a thousand bass gigs throughout the 90's with this amp and it never let me down.

48

Might be time to replace the filters.

49

I don't have a variac, but I made a lightbulb current limiter and use it a LOT. Perhaps I should get a variac!

50

Thanks for follow up, Deke. I look forward to seeing the rest of your treasures brought back to life.

I was an HF radio technician in the Army for 10 years, and I repaired a lot of guitar amplifiers after I got out. We have some very talented technicians and amp builders here, that amaze me with their expertise. Retnev gave you the absolute correct information, on how to wake up your amplifiers. I'll remember it, and put it into practice, should I need to. It makes far better sense than a "smoke test"! Best of luck with your other amps, and many thanks to retnev, for his expert recommendation.


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