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Another One Bites The Dust: SDS-DOA


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I would have to agree that finding someone willing to work on any of these amps is going to be a difficult road. It's not just the complexity of the repairs (even on the "simpler" models) it's the liability associated with doing so that may have even good-hearted folks heading for the hills.

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For neil's amp, the 4 pots on the front panel HAVE TO CHANGE. Plus

they have to be wired differently. Schematics of the modifications

have indeed been tested and work fine. But spritzer needs to test

his way on his amp.

Good news, Mouser treated me to some free Fedex International Priority so I should have the parts soon. :)

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Out of college 34 years ago i went to work for zenith radio

and learned lots from the true tube masters that worked there. Most of which

were at least 30 years older than i was at the time.

Damn when you say something like that I picture something out of an old kung fu flick where there's like some badass kung fu master who has retired into seclusion where he continues to train and refine his chi in some hermit cave somewhere.

I want to meet one of those dudes. Frankly I thought you were one of those guys, but apparently there's a level or two up? Well I guess knowledge is broader in many ways.

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From what I understand, aside from that useless "bias pot"/voltmeter crap on my amps front panel, fixing the inside to 'generally work' can be done by my tech. The issue with the power supply is more problematic as it is essentially built to fail ("go boom" as Kevin likes to repeat to all of us). If I can get Justin or someone to build me a Blue Hawaii supply that is compatible, and inside my current casing (don't worry we'll slash off the "SP ES-2" and write "Justin Rules" or something like that ;), I would have a working amp again.

An alternative solution is getting someone to build, from scratch, Kevin's "fix", but into my casing.

Hmmm... maybe Kevin could do that?

Neil

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Good news, Mouser treated me to some free Fedex International Priority so I should have the parts soon. :)

If this all works out I'm going to fly you out to my place so you can stay with me for a few days, get a vacation out of it.... oh, and fix my amp :beerchug:

Trust me, I live in a vacation spot for sure.

Neil

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I want to meet one of those dudes. Frankly I thought you were one of those guys, but apparently there's a level or two up? Well I guess knowledge is broader in many ways.

Hey at the time i was one of those wippersnappers that did (god forbid)

"sand" The art performed by those tube wizards was amazing. Especially

the stuff that zenith did for the military. There were all these rules that

everyone paid attention to back then, like the fact that all passive components

had to be secured at both ends. All wiring had to be tied together every inch

with a loop and continue... None of mikhail's air mounting of components.

Or mounting a component at one end and soldering unsecured wire to the

other. That kind of crap would never have been tolerated. Go and look

inside any 50 year old tektronix tube scope and see how the stuff was built

to last forever.

Most people don't know this, but image intensifiers was a zenith invention.

The BHSE supply will supply +400, -400, one of the 2 filament supplies and

the bias supply. And it will certainly fit in that box. To finish the thing correctly

you need one more filament supply (a transformer is just fine) and a small

C- supply, plus new umbilical cables and connectors.

Then in the amp box you gotta get brutal. Unsolder every fucking piece of wire.

Get the board out there. Take a dremel tool and cut away circuit lands to seperate

the two filament sections. Then modify to take the 4 new output tube bias pots.

Then replace the 50k pots with 5k pots and hide those inside somewhere...

Use 10 turn pots and hopefully they will fit in place of the old ones on the front

panel (pretty sure they will fit if they are at least .9 inch center to center).

Use really cool locking 10 turn turns counting dials.

And when you get done it will work forever.

But an all tube power supply would be way cool, and a bunch more work.

And i forgot the best part. Take the fucking orange drop cap out from being

in series with the audio note cap that is already rated for voltage.

Edited by kevin gilmore
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Hmm... sounds like a walk in the park. A park in HELL. I have no idea how to do this. But... for someone who does and has the proper 30-40hrs to burn, it seems like this could work.

When my tech saw the orange drops he laughed, shook his head, and refused to comment further less he sully his perfectly cordial and mild-mannered English nature.

Neil

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  • 3 weeks later...

THIS JUST IN!

ironbut reports that he has resurrected Satan's Demonic Sauce! Steve has had the amp for a couple weeks and after reading all of the comments in this thread and testing parts and replacing some parts and doing some kind of deal with the devil, the amp is back to form as of this evening. I am thrilled and hopeful that we can keep it that way for awhile. Thanks so much for the help of KG and the rest of those who posted here. I may yet have a new PS built at some point along the lines Kevin proposed but for now I will just cross my fingers and listen to it.

Most thanks go to Steve, of course, and I really owe him for his efforts (in more ways than one!) ;) Maybe there is hope for some of the others out there struggling...

In honor of the passing of the great Walter Cronkite, I will borrow his sign-off:

And that's the way it is. :)

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Thanks everyone. I don't think I will be taking this one to meets anytime soon. Thanks for the offer JP, and we can chat about how to retrieve it eventually. For now, Steve is burning in the new parts and making sure it stays functional. Hopefully he'll listen along the way too. :)

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