Hello all,
Going through first restoration steps on this Sherwood:
- two voltage doublers (120uf) replaced with 150 uf
- can cap of 120 uf and 40 uf replaced with discrete components mounted on perf board
- 4 output capacitors couplers replaced
- a couple of other caps replaced, I left the blue ones for now, especially in the FM section and in the tone control loudness part (practically unreachable)
What remains is replacing double 50uf 500v can with a JJ (for now, I use two 47 uf/450v caps with alligator clips for testing, I know not enough voltage ratings), replacing quad can (30-30-20-60) with a JJ 32-32 and discrete components underneath. Also, adding 10 ohms sensing resistors from cathodes to ground (I saw a bit of redplating yesterday, maybe the old Fisher's 7868's are on their last legs...?).
So, I placed an order today for the two can caps, one 80uf 500v to replace the 60uf part and a quad of EH 7868's.
Now, stereo fm is operating with outstanding separation (even if some tubes in the fm and mpx string test low on my Jackson). How do I know: when doing the sound test, a Beatle song was playing panned hard right and left and there was no trace of Paul's voice in the left channel.
Here's the bug: the neon light doesn't respond to stereo reception. It light up sometimes but between stations with a lot of hiss...! It also lighted up yesterday randomly when selector was placed at phono position???
Is it possible that the neon is just shot? Something more touchy with bad alignment?
Anyway, this thing is a beast, heavy and cluttered inside. Quite dirty too...
Thanks,
Patrice
Link to schematic: https://1drv.ms/b/s!AsCftN_jdRMFr1W8Ry9ppj8CsgMy
Going through first restoration steps on this Sherwood:
- two voltage doublers (120uf) replaced with 150 uf
- can cap of 120 uf and 40 uf replaced with discrete components mounted on perf board
- 4 output capacitors couplers replaced
- a couple of other caps replaced, I left the blue ones for now, especially in the FM section and in the tone control loudness part (practically unreachable)
What remains is replacing double 50uf 500v can with a JJ (for now, I use two 47 uf/450v caps with alligator clips for testing, I know not enough voltage ratings), replacing quad can (30-30-20-60) with a JJ 32-32 and discrete components underneath. Also, adding 10 ohms sensing resistors from cathodes to ground (I saw a bit of redplating yesterday, maybe the old Fisher's 7868's are on their last legs...?).
So, I placed an order today for the two can caps, one 80uf 500v to replace the 60uf part and a quad of EH 7868's.
Now, stereo fm is operating with outstanding separation (even if some tubes in the fm and mpx string test low on my Jackson). How do I know: when doing the sound test, a Beatle song was playing panned hard right and left and there was no trace of Paul's voice in the left channel.
Here's the bug: the neon light doesn't respond to stereo reception. It light up sometimes but between stations with a lot of hiss...! It also lighted up yesterday randomly when selector was placed at phono position???
Is it possible that the neon is just shot? Something more touchy with bad alignment?
Anyway, this thing is a beast, heavy and cluttered inside. Quite dirty too...
Thanks,
Patrice
Link to schematic: https://1drv.ms/b/s!AsCftN_jdRMFr1W8Ry9ppj8CsgMy