Thought I would introduce myself with my latest project. I picked up a non-working M1.5t a few months ago off that auction site. According to the seller it was recapped by their technician, however the unit smoked again shortly after it returned. The 50 and 80 volt caps were replaced with what looks like a Kall board. Original Spragues were still on the 125v rail. Not all caps were replaced, most of those that were are Nichicon FG in the power supply, which wouldn't have been my choice there.
Most of the damage appears in the right channel. Q2, Q4 and Q5 tested short out of circuit. Q13 and Q20 are short, with associated resistors burnt to a crisp but not open. Trying to figure out if these were a result of the output and first commutator shorting. Q17 is short as well. Q17 looks to have been replaced once before as there's an NTE component there currently. Other than these shorted parts, a diode or two are questionable and probably need to be lifted to confirm. The triac was replaced with a NTE part as well. I plan on double checking all boards and replacing the fried components. Then I will replace the diodes in the bridges with 6AT diodes, and upgrade the FGs in the power supply to Panasonic or Rubycon once its again functional. I've read the service manual many times and tried to learn a little more each time. Still have some questions on operation of parts of the circuits that I will need the techs to help me understand, but have the operation of these units down for the most part.
The M1.5t is a later serial number 14361, but has the "One thousand two hundred watts" face plate so kind of confused a little there. As I understand it, there was an issue with power ratings and that language was removed. Wondering if the original face was damaged and replaced from parts units.
I have been collecting test gear for a few years now. My most recent purchase was a HP 209A in nice condition, works with a clean signal but a side project is a go through on that. Also have a Rigol DS1054 that I bought to tweak some of my tube designs last year. Got a Metcal soldering station a year or so ago for a good price that works great, temp control is awesome. Last thing on the list is a set of load resistors. Leaning toward some of the aluminum cases 1000w units based on price, but if there are other recommendations, I'm certainly interested.
My OCCD started in 2011 with my first non-integrated receiver / amp. I defected to tubes until last year when I pulled out the carver gear and forgot how good they sound, even without a refresh. Looking forward to getting the M1.5t back in service and I will try to document as much as possible on this rebuild. Thanks