Sure...I was asking because I have a 700 Series II. It works nice but, for safety reasons, I would prefer to replace the mix of transistors in the output stage (complementary). Most of the output devices are the original Motorolas TP9054/MJ15025 but some Necs and Toshibas are running together with them.
Just few comments after retrospective reading:
1) Follow the amp. checkup procedure as very well described in P/L service manual + bulletins, use light bulb test when powering up - great advice of d3imlay that I appreciate.
2) As recommended in the P/L service manual ad further bulletins, output transistors (in each channel) should ALL be of the same type (e.g. MJ15024/25 or MJ21196/95 respectively for full comp. stage). In 700 Series II full complementary amp, the drivers and output transistors are the same. For example – the driver for the MJ15024 output transistor is a MJ15024. Same comment for the MJ15025 (PNP match for the MJ15024). In other words DO NOT mix different types of output transistors in a single channel. The previous statement is very important when doing service or repair work – not only with P/L equipment, but any kind / brand of amplifier.
3) In order to cure oscillations the capacitors a 22~47pF usually work well to damp out any such tendency. The factory recommended 150 ~ 270pF value might be too high, and can cause high frequency slewing at high output power. Ceramic types are recommended with at least a 100-volt rating.
3) I agree with d3imlay not to overshoot with a wide scale of replacements with all kind of kits generally available. My 'own list' for renovation musts, on top of output transistors mentioned above if mixed, includes however:
- electrolytic caps (for the PL-36 driver board I'd try to stick to one high class brand/make for audio applications; for power caps I'd go up to ca. 20.000uF paying attention to bridge rectifier and bypass small caps);
- IC LF356 replacement (might be done with your amp by the factory - TBC);
- resistors (per each channel: R1, R101, R103 - especially those getting hot may drift after 30Y+) and emitter resistors 0,33ohm (if you replace - pick HQ with 1% tolerance 5W);
- power cord (non-polarized - watch-out hum problems, valid for EU export versions)
- output protection circuit to be added - there are few options for P/L 700 series II (don't forget to reconnect RF circuit from speakers output...).
After the off-set regulation you will enjoy the sound of your beauty beast
!
Regards.