William,
Here are some links to the output transistors available today for the soundcraftsmen models with mosfet outputs.
http://www.profusionplc.com/pro/gex/...teral%20mosfet
Hitachi - Exicon replacement
N Channel
2SK133 - TO3 metal ECF10N16
2SK134 - TO3 metal ECF10N16
2SK135 - TO3 metal ECF10N16
2SK175 - TO3 metal ECF10N20
2SK176 - TO3 metal ECF10N20
2SK1056 - plastic ECX10N16
2SK1057 - plastic ECX10N16
2SK1058 - plastic ECX10N16
2SK2220 - plastic ECX10N20
2SK2221 - plastic ECX10N20
P CH
2SJ48 - TO3 metal ECF10P16
2SJ49 - TO3 metal ECF10P16
2SJ50 - TO3 metal ECF10P16
2SJ55 - TO3 metal ECF10P20
2SJ56 - TO3 metal ECF10P20
2SJ160 - plastic ECX10P16
2SJ161 - plastic ECX10P16
2SJ162 - plastic ECX10P16
2SJ351 - plastic ECX10P20
2SJ352 - plastic ECX10P20
Magnatecs...
http://www.semelab.com/magnatec/mosdata.shtml
These seem to be new by magnatec. I haven't compared the electrical characteristics with the original hitachis yet.
http://www.semelab.com/magnatec/alfet.shtml
And here too...
http://export.farnell.com/jsp/search...525460,1525560
I read a while ago in the diyaudio site that the exicons (profusion) and the magnatecs are made by the same manufacturer.
Renesas (previously Hitachi) does not seem to make them in the TO-3 packages (metal) anymore and only makes the in TO247 (plastic). Maybe I'm wrong.
Link...
http://america.renesas.com/products/...n_amp_root.jsp
Another link...
http://tech-diy.com/Store/LatFets.htm
Don't go for to ebay for the mosfets unless you want to get robbed.
I would replace all the capacitors (money permiting) on that amp. And maybe the bias trim potentiometer for something of a better quality.
See this link...
http://www.tnt-audio.com/clinica/bias_e.html
Once it is running it will impress you with is clarity, balance and control of the whole spectrum. You won't believe an amplifier that old can sound soooooooooo good.
I can provide a schematic. Shoot me a PM.
BTW, blowing fuses means shorted outputs. But just to make sure which channel is out just must disconnect power from these one at a time. Do not do this with the power on and make sure the ends of the wires you disconnect are taped to avoid them touching the chassis or you! There's 75 volts on the secondaries. If you don't think you can perform this diagnosis let someone with more experience do it. But if you're going to replace them with exicons or magnatecs you may as well replace all 8 mosfets.