got hold of a rotel power amp
the mains transformer has gone short circuit 2x 40v 0 40v
blown 5x 2SB817 2x 2SD1074 2x 2SB631K
what i would like to know is there an equivalent to the 2SB631K please see pic for the schematic
also the caps highlighted in schematic c609 & c606 should they be low esr or standard
c606 it only shows 1 on schematic but the pcb's are both populated with the caps
has anyone got a transformer or 2 that i could stack to replace the original UK ONLY
Regards Glenn
the mains transformer has gone short circuit 2x 40v 0 40v
blown 5x 2SB817 2x 2SD1074 2x 2SB631K
what i would like to know is there an equivalent to the 2SB631K please see pic for the schematic
also the caps highlighted in schematic c609 & c606 should they be low esr or standard
c606 it only shows 1 on schematic but the pcb's are both populated with the caps
has anyone got a transformer or 2 that i could stack to replace the original UK ONLY
Regards Glenn
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Are you 100% certain the mains transformer is toast? IME, Rotel's PTs are extremely reliable and rarely fail, especially the dual secondary toroidals.
Even if you had a single dead secondary, you could temporarily run both channels from the working secondary side, until you located a donor unit on ebay to scavenge the PT. The entire thing is SE common ground so it would be a piece of cake.
Even if you had a single dead secondary, you could temporarily run both channels from the working secondary side, until you located a donor unit on ebay to scavenge the PT. The entire thing is SE common ground so it would be a piece of cake.
it blew a 3A fuse in the mains plug
i haven't got a 100w bulb to put in series with it to test it for shorts ( it got broken ! )
the 240V primary's measure 5 Ohms
i haven't got a 100w bulb to put in series with it to test it for shorts ( it got broken ! )
the 240V primary's measure 5 Ohms
That seems quite normal for a +300-400VA transformer 😉
Remove/unsolder all secondary leads. Does it still blow the primary fuse??
C606 and R606 must certainly be present in both channels. C606 doesn’t matter too much but C609 conducts all the audio. It’s an amazingly high value at 1uF around the bias spreader. You could consider a film cap in this position.
2SB631K - KEC make an equivalent - KTB631K. It is fully encapulated but they work just fine.
You could try Profusion, they might have them.
You could try Profusion, they might have them.
Oops, I checked Profusion but they don't appear to carry them.
I have sourced them from LCSC Electronics, https://www.lcsc.com.
They are in China but a reputable source.
I have sourced them from LCSC Electronics, https://www.lcsc.com.
They are in China but a reputable source.
i have found a transformer with the right voltage but it only has 1 output 40-o-40 the original had 2 separate outputs
can i parallel the amp modules together as in connect both to the same transformer
or should i remove the rectifiers from the amp boards and just use one rectifier to feed the caps on both boards
can i parallel the amp modules together as in connect both to the same transformer
or should i remove the rectifiers from the amp boards and just use one rectifier to feed the caps on both boards