ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Hi all, I apologise if I have posted this in the wrong section, first timer.
I have a 4002 5511 that I bought second hand about a year ago. All the maintenance I have done has been freeing up the tone arm mechanism and drive scrrew. It has been running well (with maybe some very slight speed fluctuations).
I recently played some 45's and although it started the first record fine, I noticed the platter slowed a few times then got back up to speed.
More recently it has significantly slowed to roughly half way between 33 and 45. Starting and stoping doesn't seem to help.
33 still seems to work fine and the speed selector switches as it should.
I have downloaded the service manual but thought I would ask for advice before pulling it apart.
Any suggestions would be appreciated.
Thanks
Since only the 45 speed is faulty I would would suspect dirty contacts on the speed change relay and/or the bad speed adjusters (trimmers) on the main pcb.
I had a 4002 that fluctuated on both speeds and that turned out to be the motor.
Regards Graham
Agreed, and don't forget the 45 thumbwheel potentiometer on the Keyboard panel - IIRC its a 1KOhm unit.
If that is the problem and it's non-repairable, it's very easy just to bypass it - it's really not necessary, if the speed trimmer poti on the main PCB has been set correctly.
Menahem
Thanks guys. The Thumbwheel pots seem to be reading consistanly with a dmm. (Not dirty) so I think they are ok. Haven't pulled the relay apart to have a look yet.
Which pot is the speed trimmer on the main PCB?
Ended up being a dirty R14 Pot. Cleaned up with some fluid and enthusiastic adjusting. All seems fine now.
Thanks again.
Mine was slow on 33 and varied from 31.577 up to 32.212. R15 pot took care of mine. Now running 33.014 - 33.118.
How did you measure the speed so accurately?
I do balancing of fans, pumps, etc. as part of my living. In order to measure the phase of the unbalance, I employ a laser tachometer. So to measure the RPM of the turntable, I put a piece of reflective tape on the platter and set the laser to measure the tape.
Unfortunately mine has started slowing down again off and on. I'm thinking I will purchase a couple new pots and put them on the board. Does anyone know what the values are for R14 and R15?
Dave
Once you've got the TT disassembled, do all 5 pots.
Use Piher PTC10 units.
Type 5513 DC
PCB1
4.7K R14, R15 (Can use 5K)
22K R56, R57, R88 (Can use 20K or 25K)