Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: firemedic on November 02, 2012, 02:10:14 pm
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I'm wrapping up the AIMS Dual Twelve rehab job. The tremolo does not work. The nominal voltages for the tremolo circuit are pretty close to right on & I guess the weak link must be the optoisolator.
The LED flashes like it should but the light sensitive resistor looks really old and like it washed in from the sea. Also, the LED & resistor are just located next to each other with no covering at all.
My question: would Doug's roach work in the circuit? It's pretty much the same type circuit as what Fender did so I'm thinking the answer is yes.
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Also, the LED & resistor are just located next to each other with no covering at all.
I'd try putting a piece of shrink wrap over the 2 first to block any light in or out. And make sure the R has it's light reading element facing the LED.
Brad :icon_biggrin:
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Yeah, the element is right on the LED, and I tried the wrapping it in electrical tape just to make sure.
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Just turn off all the lights. Does the trem work now? If so, tape up the LED and LDR.
If the LED flashes OK, then go to RadioShack and buy that 5 pack of CdS Photoresistors (Catalog # 276-1657). Find one that works well and tape it up.
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Stand by for results. The local Radio Snack employees run & hide when I walk in because I ask for things they've never heard of, every time. And I never buy batteries or phones.
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A couple months ago I showed the sales guy the difference between shorting and non-shorting 1/4" jacks. He looked at me like I had just invented the semiconductor and remarked "I really need to learn more about the things we sell.".
They do know their batteries, though. :icon_biggrin:
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Just say "give me one each Catalog # 276-1657". They understand that. The package may be dusty! :icon_biggrin:
I bought the 5 pack a few years back when I restored a Sunn Sceptre.
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> Radio Snack employees run & hide .. I ask for things
Don't ask. Learn "The Look", which means "I know what I want and which wall you hide it on; so leave me alone until I need to pay".
> the sales guy ... remarked "I really need to learn more about the things we sell."
No he does NOT. Radio Shack actually had a policy of NOT hiring geeks. Knowing the stuff is not as good as knowing how to SELL. If he knew something, he'd have to hide that fact or never move up.
> They do know their batteries, though.
I was shocked. I thought you could still buy Ni-Cads at Radio Shack, _and_ that I could find a Ni-Cad quicker than the cellfone pushers. No Ni-Cads! Only LiON or whatever. I pointed this out, the young guy agreed, but the old guy (half my age, sigh) said "WAIT! Solar Driveway Light battery!" Sure enough, there was a special pack for solar lights (which is what I wanted it for), the fine print said Ni-Cad.
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There are some cool ratshacks in the tiny little towns around here.One is a gun/pawn/music/radio shack.I picked up some cool old germanium tarnsistors there.The othe ris a convience/gas/liquor/radio shack
No pressure to buy cellphones at those.
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No he does NOT. Radio Shack actually had a policy of NOT hiring geeks. Knowing the stuff is not as good as knowing how to SELL. If he knew something, he'd have to hide that fact or never move up.
And that my friend is why I still sing and play the blues. :sad2:
Brad :laugh:
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Don't ask. Learn "The Look"
I think I had that down pretty well, but they're kinda pushy down here and seem to take it personally that I don't want advice or help of any kind. In fact, I think they must believe I'm building bombs or something.
I had a great independent supply store not far from me, that had just about everything. Unfortunately they closed down last year, and the only other places that have parts, don't sell them; you're expected to leave your amp carcass & hope they can fix it.
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Well, the lady at RS was very nice and helped me find the package of photocells when I was too obtuse to see it myself. She also told me RS was going to start carrying more & various items in the near future. Plus they had desoldering braid. So I guess I'll have to stop slagging Radio Shack.
The tremolo works! Chalk another one up to the forum. Thanks, sluckey!