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Hi,
I currently restore an old Beogram 4002, and I have already performed the following:
My problem is that the speed is too low.
Despite the VR15 (used to adjust the 33rpm) and VR14 (adjusting 45rpm) are both at their maximum, I obtain:
Do you have suggestions of what I could do to fix this speed problem ?
Can it be the relay ? the motor that requires to be lubricated ?
Thank you for your reply,
Wrong belt? The standard belts sold on f.e. Ebay are typically too tight, putting a to high load on the motor.
Relays are almost always bad but typically cause instability or complete failure rather than a permanent low speed.
Do you have an AC or DC motor version deck?
"the C10 caoacitor has been changed from 0.33µF up to 10µF has it is said on this site that this helps to fix the speed stability problem."- Where did you read this?
Martin
Hi Dillen,
The belt is new, it has improved the results over the previous one...
By reading the various posts related to the Beogram 4002, it appears that the speed and instability problems are very common. There are multiple causes that may explain this...
Regarding the C10 cap, I have read this on Beolover here: https://beolover.blogspot.com/2017/03/
The guy had the same pb and the capacitor change solved the issue....
I agree that the relay might be defective, it is probably the next replacement I will do.
"Do you have an AC or DC motor version deck?" --> I check and I comme back to you (I believe it is a DC motor but not sure)
As there are various possible causes, I try to get advices...
The C10 capacitor swap was a final fine tuning of the platter motor speed stability after a rebuild of the DC platter motor where the two bearings are re-infused with oil and, if necessary, new snubber diodes are replaced on the motor. After that Beolover did a long term (24 hour) speed stability test. He determined in that case the 10uF performed better than the original 0.47uF (in his case). You have missed two important restoration steps - rebuilding the platter motor (the most likely cause of your speed instability) and replacing the speed select relay (another problem source). The order to restore these are motor rebuild first followed by changing the speed relay and recapping the control board. I also like to replace the two speed adjustment trimmers to multi-turn type trimmers but that is optional. As I said earlier, the motor is the most likely problem and will start to misbehave before you start hearing it squeaking. After all it is over forty years old on the original oil-infused bearings.
-sonavor
One other thing about the C10 capacitor...It is interesting that the Beogram 4002 and 4004 service manual schematics both call out 0.33uF for the C10 capacitor but we have seen units with 0.33uF, 0.47uF and 10uF capacitors. So it is something B&O changed based on some sort of testing or evaluation that I have never found any documentation for. I would recommend keeping your original value of C10 until you can test out that one of the other values performs better (by plotting the speed stability over a long period of time the way Beolover did). Also, the change in C10 for his example got rid of some occasional spikes in the speed that were too short and too infrequent to have been noticeable by human hearing. The C10 capacitor by itself would not be contributing to your slow speed issue.
Something else bothers me about your speed issue. Are both your 1R14 and 1R15 speed adjustment pots maxed out (for 33 1/2 RPM and 45 RPM)?If that is the case are you certain you replaced the them with 5KOhm trimmers? What about the 2R1 and 2R2 trimmers? What position are they in?
nounours18200:The belt is new, it has improved the results over the previous one...
Where did you buy your belt ?
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