Mystery Sylvania Console 7868 PP Amp

Andyman

Scroungus Stereophilus
Subscriber
Coming home from the library today, i just HAD to swing by a Moving Sale. Not much in the garage, but I was told there was more inside and once in the kitchen I see a big picture of a console taped to the fridge. I find it in the basement and with the use of a flashlight I see it has not the usual 6BQ5 or 6V6 tubes, but 7868s. a quick call to Kegger confirms it is worthy and with his help I get the very heavy console home.

But I'm not finding much on line about this amp at all and there's some handiwork been done on it (not the extra caps and the sloppy solder on the filter cap, which may be a replacement.

Anybody have any experience or ideas on what I have here? FWIW, the iron looks to be very hefty, so I think this amp has a lot of possibiliy :yes:

BTW, the last pic of my new buddy is pretty cool too. He came along home with the console :D

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Heck the Louis statue is worth a lot! Very nice; wish I had it.

The amplifier, well average stereo not so hi fi.
 
Louis is a bit dinged up, but still looks good and has managed to keep his smile.

As to the amp, do you have any experience with it? I ask because the Maggie amps can be made to sound quite nice; Kegger really did a great job with my 8802.

And the transformers in this one are way beefier than the Maggies, so I'm hopeful for them.
 
spec wise, the 7868 looks like a nice little tube. I'm seeing 28 watts for push-pull class AB1 at 450v and its rated for up to 550v on the plate. Thats pretty darn beefy. If the transformers can keep up with the tubes you should have a nice little rocker on your hands.

and yeah, previous repair job looks shaky. Poor solder and a zip tie to hold the cap in place? tsk tsk.
 
Yep, I'm wondering about that whole second filter cap as it also has that big silver Mallory under the chassis tied in too.

It sure would be nice to find some sort of schematic for this to see what's supposed to be there. the chassis has "12AU7" scratched into it by the driver sockets, but they have 12AT7s stuck inside.

Very interesting...:scratch2:
 
Yep, I'm wondering about that whole second filter cap as it also has that big silver Mallory under the chassis tied in too.

Looks like a previous owner tried to repair it by strapping new caps in parallel with the old possibly failed open caps. You want to replace it all. Old caps can short out, which can ruin the power transformer. Look at the ratings of the original filter caps to find out what new caps you will need. New individual caps mounted underneath would work, as finding can multicaps in harder than individual caps. And replace that red cap under the chassis too.
 
Understood, but that second cap has some big values on it, so I'm a bit surprised. I don't recall seeing a filter cap over 100 uf, but the big one had ratings as follows:

120 uf @ 250 VDC
60uf @ 250 VDC
40 uf @ 475 VDC paralleled with the silver 40 uf @ 475 VDC under the chassis for an effective 80 uf. Those 250VDC ratings seem a bit low to me also

That brown one is "interesting" too. It's a dual stage 100/10uf cap with the 100 uf lead clipped off and the 10uf leg installed in parallel with the 40 uf@ 475 VDC leg of the smaller cap.

This is why I'd like a schematic, as those ratings on the replaced large cap with the nasty soldering job seem too unusual for stock to me. I think something just got tossed in there and hoped for the best :dunno:
 
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That's a very cool tube to find in a console amp. I'm betting if they went to the trouble to use that tube, the iron is pretty good too, maybe even excellent.:dunno:
 
Yeah, that's pretty much what Kegger and I talked about too when I called him on it. I'm going to guess it will wind up on his bench at some point in the future as he seem pretty intrigued with it yesterday.

I like the layout on it too with the 3 tubes split by the power tranny; it makes a nice statement and doesn't have the filter cans mucking up the view either.
 
Yeah, but the scratchings on the chassis say 12AU7, so more monkey bidness :dunno:

I know Keg likes the ATs too though..:yes:
 
Indeed!

He certainly did a killer job on this Maggy 8802 of mine I've been playing for the last week. :thmbsp:

This 7686 could wind up being my big (ger) gun as it could be around 25 wpc based on my finest WAG :D
 
Oh yah we can do something nice with that guy I'm sure, it even looks like a choke
in the supply there as well, dam though gunna have to go solid state rectification..:sigh:
 
Oh yah we can do something nice with that guy I'm sure, it even looks like a choke
in the supply there as well, dam though gunna have to go solid state rectification..:sigh:

That's a good thing ol' Pard.:D Get yourself some nice 6 dollar hexfreds from AES.
 
Is it rectified already? There looks to be a couple little diodes off the power line on that terminal strip already, but hey, I know squat about these circuits...
Look over the big red cap and to the right and above the brown disc cap...
 
Yep the little black diodes there are doing the rectification.

Just drop that thing off here and will figure what to do............:naughty:
 
Lots of houses here for sale for probably less than you make before lunch buddy :D
 
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