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Old 23rd July 2014, 02:13 PM   #11
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Enzo, will measure diode bridge using diode test of DMM since the secondary AC connections are removed.
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Old 23rd July 2014, 03:13 PM   #12
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Remove the wires that feed the + - 48v rectifier. Test again.
Blowing a 4A fuse in the primary is a substantial short circuit! Disconnecting the transformers secondary windings will rule out either the rest or the transformer.
Keep it simple and take photographs on your mobile phone to aid rebuilding.
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Old 23rd July 2014, 03:18 PM   #13
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Jon, the T1 secondary wires that supply the AC to the rectifier were removed and DLB good. Transformer is good.

Are you saying to remove the DC output from rectifier and test again? This would tell me the rectifier is good.
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Old 24th July 2014, 12:34 AM   #14
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confirmed tonight pair of output devices and a pre driver on one side of the amp are blown. confirmed by finding shorts between pairs of leads on each of the devices.
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Old 24th July 2014, 12:45 AM   #15
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Good to know, but a bummer.. I imagine finding replacement transistors for this amp could be a little tricky.
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Old 24th July 2014, 02:05 AM   #16
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2SB755 and 2SD845 Toshiba does anyone have a set they want to sell?
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Old 24th July 2014, 09:00 AM   #17
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Nobody does, and if you find them they will be fake. You'll have to find modern equivalents. That is, different product number, different (but compatible) specs. Start by looking at the datasheet and case type, then look for new transistors with the same case. You're bound to find something similar.
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Old 24th July 2014, 09:21 AM   #18
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2SB755 TRANSISTOR (JR 2SBB1) | eBay

2SD845 Original Toshiba Transistor D845 BRAND NEW FAST DISP x 1 pieces Uk Seller | eBay

I would use a pair of T03p transistors of a similar grade and drill and tap the centre of each mount.
There are still plenty about.
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Old 24th July 2014, 09:23 AM   #19
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Have you tried an established Technics/Panasonic Repair Agent in your area, for spares?
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Old 24th July 2014, 09:24 AM   #20
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Quote:
Originally Posted by rfitts46 View Post
Jon, the T1 secondary wires that supply the AC to the rectifier were removed and DLB good. Transformer is good.

Are you saying to remove the DC output from rectifier and test again? This would tell me the rectifier is good.
Sorry but I could see no reference to you having removed the secondary load.
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