I posted this question before on previous thread but I think was offtopic.
I Have 2 1400mk2. I changed all electrolic capacitors from both last month for maintenance. One of them works perfect, the other has a speed problem at 33 RPM +1.1 PITCH or slower.
The problem is the same as you can see at the following video (here is with a 1200mk2)http://www.youtube.com/watch?v=vAWjh3MKLX4
If I pulse several times the 33 RPM switch, the problem seems to be ended(until I brake the platter with my hand or change to 45 RPM and then to 33 ...). If the pitch is equal or over 1.2% the platter spins perfect. At 45 RPM all is working well...
I've a scope and I can view some strange things: for example a 2 HZ pulse (15 V to 0V) at 20 PIN of the AN640 'Drive' IC (this pin is for "Phase condenser"). Some noise at cap C5 of the PSU at 2 hz too. AN640 is OK.
All components (resistors, caps, diodes and transistors) were tested with my multimeter and seems to be OK... The motor system is OK too (turntable were tested with the motor of the other one), Power transistors TR1,4,7 were changed...
I don't know sure if there's relation but I can hear slightly some high frequency noise from the transformer (at 33,45 and stoped, that noise ends if I accelerate or slow the platter down with my hand).
Do you know what could be wrong? It's going me crazy!.