Technics SA-400 Repair(STK-0040)

Noodle

LISTEN! I smell Hi-Fi.
First, a pre-"thanky" for any help
I'm not too familiar with Technics units, I always piddle with Pioneer.
But a friend has let me diagnose a unit for him that blows the main 4A fuse on power up.
I put a 3A fuse in it's place, hooked the unit to a DBT and the bulb stays bright.
I did pull diodes D701-704 and D705 & D706, they all checked out.
So without removing the STK-0040 power packs, I did de-soldered pins 1,2,3,7,8,9 from the board, checked for no connections from these pins to the solder pads, good there.
Hooked the unit back to the DBT, powered up and the light went dim.
I check for a short from pins 2 to 3 and 8 to 9 on both packs, one pack showed a short between those pins.

Questions:
I suppose there is no replacement for this shorted pack?
An original replacement is my only hope, correct?
 

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I have a Technics SA-300 that bas 0039 Paks in it. If the inside layout is similar I'm quite sure they would fit. The discrete replacements are wired.into the power board(not pins like a standard pak) so there is some flexibility in how they mechanically attach. Take a.picture and I can compare it to mine.
 
I have a Technics SA-300 that bas 0039 Paks in it. If the inside layout is similar I'm quite sure they would fit. The discrete replacements are wired.into the power board(not pins like a standard pak) so there is some flexibility in how they mechanically attach. Take a.picture and I can compare it to mine.

Pic as requested.
 

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I have a Technics SA-300 that bas 0039 Paks in it. If the inside layout is similar I'm quite sure they would fit. The discrete replacements are wired.into the power board(not pins like a standard pak) so there is some flexibility in how they mechanically attach. Take a.picture and I can compare it to mine.
would have to do some checking of supply voltages before down rating .
 
Chinese STK-0040 and 0050 are available from multiple sources, I'd search a bit here at AK to see the experiences of other buyers and buy from some source mentioned here. They are cheap, so if they fail you can buy another one from other vendor. They usually work. Some don't, but most of them work fine.
 
First, a pre-"thanky" for any help
I'm not too familiar with Technics units, I always piddle with Pioneer.
But a friend has let me diagnose a unit for him that blows the main 4A fuse on power up.
I put a 3A fuse in it's place, hooked the unit to a DBT and the bulb stays bright.
I did pull diodes D701-704 and D705 & D706, they all checked out.
So without removing the STK-0040 power packs, I did de-soldered pins 1,2,3,7,8,9 from the board, checked for no connections from these pins to the solder pads, good there.
Hooked the unit back to the DBT, powered up and the light went dim.
I check for a short from pins 2 to 3 and 8 to 9 on both packs, one pack showed a short between those pins.

Questions:
I suppose there is no replacement for this shorted pack?
An original replacement is my only hope, correct?
I picked up a forlorn, grimy, cigarette-smoke-impregnated SA-400 at a local thrift shop that would not power up. After the obligatory De-Oxit/Simple Green/Windex flush-out, I desoldered the STK-0040s, pulled them out along with the large heat-sink, and re-installed STK-0050s with super-conductive (read: EXPENSIVE) thermal compound. The monster sprung to life, and, after an hour or so of major, high-decibel rocking out, the upgraded power packs were loafing along at a balmy 76 degrees!!! Whenever possible, upgrade.
 
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