I am sorry but I am not sure about the RPM.
Never came an issue that I need to measure it.

PS..I do not think it is high, 6500RPM one would suffice. Just guessing here

 

Well, ordered 3 motors and implemented one of them that seemed to fit best. Had a bit of space left in the cylinder and used some glue to fix it. Seems to run perfectly. The cooling is working and no resistors smoking, didn't replace any thus far. See the spec of the engine in attached pic.

Thanks for the support guys, topic can be closed.

 

Well done! I wasn't optimistic but you stuck to it and won. Feels good, huh?

 

It does... It sure does.
As I remember buying the set as a 14 year kid it's rather special to fix it myself as to be able to pass it on to my 9 year old daughter. Again thanks for the support!

 

I don't like to dampen your enthusiasm, but there's a fair chance the same thing will happen again at some point. The same resistor got hot in my SU-CH7 originally too - so hot that it melted itself off the board! It was not a fan problem. I replaced the PSU caps as noted in my other thread, and also replaced R573 and the nearby capacitor, C572/573. Now the resistor runs completely cool to the touch, whether the fan is on or not.

Capacitors can be bought cheaply from ebay. If you want your daughter to enjoy this stereo for many years, it's worth replacing the ones I listed. I also replaced these recently, just to be sure:

For the amp:
C713 and C714 = 16V100
C709 = 16V47

For the tuner:
C704 (10V220)
C709 (35V330)
C711 (16V100)

For the CD player:
C3 (2200uF, 25V) and C17 (100uF, 50V).

For the tape deck:
C602 (2200uF, 25V) and C603 (1000uf, 25V) and C830 (100uF, 100V).

All are related to the power circuits. If the system doesn't have good, smoothed DC then you will get overheating problems.