woodhawk1
Montana59457
Happy New Year - and with the new year it is time to dust off the Sherwood S8000. I picked up the receiver back in 2015 with hopes of restoring it over the holidays. I did go in and re-stuff a couple cans with the help of gadget73 and jaymanaa. Thanks again for the guidance.
http://audiokarma.org/forums/index.php?threads/another-sherwood-s8000-rebuild-question.645624/
And then it went on the shelf. Now a few years have passed, and it is time to get back to work.
A few images of the S8000 are attached. Faceplate and chassis are both in good shape (I really love the sleek Sherwood look). I tested the tubes on my Jackson 658A, and all pass (some are marginal). The 12AT7 was dead, and so at present a 12AX7 holds its spot (new tube is on its way).
All switches and bulbs work. Aux is clear and strong in both mono and stereo (sounds great!). FM mono is clear and strong too. FM mx is very weak (barely comes in), but what comes is in stereo. There is a minor hum that becomes audible at about 1/2 way up on the volume, and it increases as I turn up the volume. It is present on all settings (aux, phono, FM).
My goals are to:
1) get FM stereo up and running.
2) find the source of that hum and eliminate it.
3) add 10 ohm ¼ watt resistors so I can measure current on the output tubes. Right now the bias is -17.2 vdc (I don’t think there is any way at present to adjust this – my S5500ii has a pot to adjust all at once).
4) replace resistors and capacitors as needed (or as suggested).
5) add cl-80 thermistor (maybe after I determine the fate of the two 120 uf cans above - space could be an issue).
And so – first things first - later today I am hoping to add the 10 ohm resistors but I must admit the connection points are less than obvious to me at the moment. Based on the recent great rebuild thread by Dave 451 on his S8000 IV and my own experiences with my S5500ii I am guessing pin 3 is the correct connection point for the resistors, but there are wires heading off from pin 3 that cause me to pause (see attachments). One shielded wire (red arrow) heads off to the power transformer. At the opposite end of the output tubes another thin brown wire heads off to where I have yet to determine (perhaps just ground? - two wires are connected to the pin marked by the red arrow – one is connected to pin 3 on the adjacent tube – the other ???). I am also searching for a good spot to bring the resistors to ground. There is little room and no obvious great choices.
Thanks for now!
http://audiokarma.org/forums/index.php?threads/another-sherwood-s8000-rebuild-question.645624/
And then it went on the shelf. Now a few years have passed, and it is time to get back to work.
A few images of the S8000 are attached. Faceplate and chassis are both in good shape (I really love the sleek Sherwood look). I tested the tubes on my Jackson 658A, and all pass (some are marginal). The 12AT7 was dead, and so at present a 12AX7 holds its spot (new tube is on its way).
All switches and bulbs work. Aux is clear and strong in both mono and stereo (sounds great!). FM mono is clear and strong too. FM mx is very weak (barely comes in), but what comes is in stereo. There is a minor hum that becomes audible at about 1/2 way up on the volume, and it increases as I turn up the volume. It is present on all settings (aux, phono, FM).
My goals are to:
1) get FM stereo up and running.
2) find the source of that hum and eliminate it.
3) add 10 ohm ¼ watt resistors so I can measure current on the output tubes. Right now the bias is -17.2 vdc (I don’t think there is any way at present to adjust this – my S5500ii has a pot to adjust all at once).
4) replace resistors and capacitors as needed (or as suggested).
5) add cl-80 thermistor (maybe after I determine the fate of the two 120 uf cans above - space could be an issue).
And so – first things first - later today I am hoping to add the 10 ohm resistors but I must admit the connection points are less than obvious to me at the moment. Based on the recent great rebuild thread by Dave 451 on his S8000 IV and my own experiences with my S5500ii I am guessing pin 3 is the correct connection point for the resistors, but there are wires heading off from pin 3 that cause me to pause (see attachments). One shielded wire (red arrow) heads off to the power transformer. At the opposite end of the output tubes another thin brown wire heads off to where I have yet to determine (perhaps just ground? - two wires are connected to the pin marked by the red arrow – one is connected to pin 3 on the adjacent tube – the other ???). I am also searching for a good spot to bring the resistors to ground. There is little room and no obvious great choices.
Thanks for now!