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A vintage SVT comes my way, tagged "no sound". I don't even bother powering it up to check, I immediately pull out the power amp chassis and have a look:
Something's odd about the PT and OT, especially the two extra wires seemingly from the primary with the quick-disconnect terminals. Hmmmm. Stampings on the transformer end bells are the clue -- they're 1990s SVT Classic parts, and weirdly the PT is the export model with the 100V taps (the FT is original with no 100V taps). The part numbers turn up on this attachment though I can't find the relevant post:
SVT-II combined early power amp
It's completely mind-boggling that this enterprising soul replaced the transformers and yet changed out only two of the axial electrolytics and half of one of the can caps. The electrolytic in the preamp was ignored while the dropping resistor was replaced, too. I'm guessing the "repair tech" had to change the fan too:
Not that it would have mattered any:
PROTIP: Molex still sells crimp terminals and crimp tools.
Now that y'all have had a good laugh, here's the question: has anyone run into a Rev. G or Rev. H (from 1975) SVT power amp schematic? All the ones I've found are Rev's A, D, F, or I. This amp has the Molex connector wired as:
1 - signal from preamp
2 - 350 V "E"
3 - no connection
4 - signal shield
5 - 485 V "B"
6 - AC neutral
7 - heater "F"
8 - heater "F"
9 - fused AC hot
10 - fan (AC neutral)
11 - fan (switched AC hot)
12 - switched AC hot
I can't figure out why the 350 V connection is there, it's never used in any preamp schematic I've seen.
Something's odd about the PT and OT, especially the two extra wires seemingly from the primary with the quick-disconnect terminals. Hmmmm. Stampings on the transformer end bells are the clue -- they're 1990s SVT Classic parts, and weirdly the PT is the export model with the 100V taps (the FT is original with no 100V taps). The part numbers turn up on this attachment though I can't find the relevant post:
SVT-II combined early power amp
It's completely mind-boggling that this enterprising soul replaced the transformers and yet changed out only two of the axial electrolytics and half of one of the can caps. The electrolytic in the preamp was ignored while the dropping resistor was replaced, too. I'm guessing the "repair tech" had to change the fan too:
Not that it would have mattered any:
PROTIP: Molex still sells crimp terminals and crimp tools.
Now that y'all have had a good laugh, here's the question: has anyone run into a Rev. G or Rev. H (from 1975) SVT power amp schematic? All the ones I've found are Rev's A, D, F, or I. This amp has the Molex connector wired as:
1 - signal from preamp
2 - 350 V "E"
3 - no connection
4 - signal shield
5 - 485 V "B"
6 - AC neutral
7 - heater "F"
8 - heater "F"
9 - fused AC hot
10 - fan (AC neutral)
11 - fan (switched AC hot)
12 - switched AC hot
I can't figure out why the 350 V connection is there, it's never used in any preamp schematic I've seen.
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