DIY Audio Projects Forum
 NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

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 Post subject: Sansui QRX3500 No power
PostPosted: 20 Feb 2015, 18:09 

Joined: 20 Feb 2015, 17:55
Posts: 2
I would really like to fix this amp ive had it since 1973 I blew a fuse and replaced it when i turned it back on it made a humming and lost power fuse didnt blow was supposed to be a 4 amp but couldnt get any and used a 5 what could i have blown up in it thanks I love this amp would like to revive it

PostPosted: 21 Feb 2015, 23:13 

Joined: 26 Oct 2012, 21:00
Posts: 203
Location: ontario canada
output transistors; diodes in the supply; filter caps and potentially any combination of the three!! :eek:
fuse ratings are not to be taken lightly or ignored, they're in there for a reason! :eek:
before going any further in diagnosing or attempting to service your amp assemble a "dim bulb tester"(there's a thread in this forum about it and it's use. sorry can remember off the top where it located)
what sort of test equipment do you have at your disposal?

PostPosted: 22 Feb 2015, 02:20 
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Joined: 08 Aug 2009, 03:11
Posts: 2229
Location: Chilliwack, BC
An amp that old needs a recap, plain and simple.

Use standard diagnostics for the rest of the stages (a DMM on diode test will be invaluable for the transistors and diodes).

-= Gregg =-
* Ratings are for transistors - tubes have guidelines*
Home: GeeK ZonE
Work: Classic Valve Design

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