The PM665-VXi refurbish project

[wkloppen]

Hello Gents,....got my hands on PM665-VXi from Romania. Planning to refurbish it just like 640-VXi and 645-VXi. Threads and pics can by found on this sub-forum.
Measured the DC offset and Idle current and they were a bit off. Luckily you can adjust both DC and Idle on it so after adjustments I got

DC Offset:
CH-1: 2 mv
CH-2: 1 mv

Idle current:
CH-1: 27.8 mv
CH-2: 28.1 mv

So that's the starting point. The amp sounds good but not a immediate difference compared to my refurbished 645-VXi (daily driver). We'll see after the refurbishment
Thinking of buying this upgrade set with the nice Nicichon caps besides doing all the swithes, the fusible resistors and probab ly some resoldering as well. At least a nice project for the winter. ...Yes it's still wet and cold in the Netherlands.
Will use this thread posting pics of the process.....

CU

Willem

 

[The Judge]

I have found the PM665 Vxi manual is wrong regarding the bias setting. The 28 mV setting in 8 Ohm mode will not get 50 mV at the check TP´s. You may either set 28 mV in the 4 Ohm mode OR set 50 mV in 8 Ohm mode to get around 50 mV at the confirmation TP´s.
With the 0,27 Ohm emitter resistors this will give 92 mA idle current in 8 Ohm speaker mode.

Compare with the PM665 unit that has 0,33 Ohm emitter resistors and 50 mV setting (75 mA idle current).

HTH