guys,
Finally found time to restore the basket case Spec-4 I bought 2 years ago.
The amplifier boards were clearly from different batches as they had different components, one board did not even have the sleeves around strategic resistors. As both had a lot of burned parts I decided to remove (almost) all components and do a full rebuild.
I selected most parts from the part lists and advices of MtF, EW and Mattsd, including the MY-02 relay swap EW-style.
Everything worked first time right, bias and DC balance are rock stable and I get 2x180W into 8 Ohms without a problem. Power output into 4 Ohms is 390W, I tested this in burst mode to reduce dissipation in the amplifier, this translates into 10A. Following the manual the current limiter should be adjusted to 7A but the MJ21193/94 can handle more power than the originals so I took the risk for now. Anyone has an opinion?
Some negative points:
- the front has two deep and large scratches
- I'm missing the rear 'bumpers
- the housings of the two mains relays were broken into pieces, I glued them back together but I want to replace them in the end because I don't trust them, every now and then at least one of them makes a buzzing noise, haven't found what's wrong there.
Thanks for the inspiration.
regards, Peter