100-77 Topaz - playing slow

[alanj]

Hi, newbie here.  Recently bought a 100-77 Topaz in working order.   After a couple of weeks it is now playing records slowly.  I am in UK, and I already checked I've got the UK model with the correct gears (yellow dot), it was working fine before anyway, so I know it's a UK model.

I have taken cover off the select-o-matic unit and checked obvious.  It's all nicely lubricated and seems to run fine in scan mode, just when playing it's obviously slow.

I de-soldered the Motor run capacitors and tested.  1.65uf and 0.75uf.   When scanning both capacitors are switched in parallel giving 2.4uf.    When in play mode only the 0.75uf is connected (i checked the switch that cuts out the other capacitor and it's working fine.   

I re-soldered the caps and still got the issue.

Next: I tried (temporarily) adding the 1.65uf cap back into the circuit in play mode.   This improved the situation and the speed increased, but not as fast as it should be.   Why is that, I thought a larger cap would slow it down? Unless the extra torque is helping it to overcome some physical resistance issue I have???

Any pointers greatly appreciated please.

Many thanks,

Alan

[alanj]

Update: Checked all the electrics and all looks fine. Checked the rubber/plastic connector between the motor spindle and the gear worm drive is not broken or slipping. I am awaiting full service manuals from USA, but in meantime I have a pdf service guide for a very similar model.

The service guide almost seems to imply you have to totally strip the mech down to components parts and re-build. I don't feel confident (yet) in doing that - so I'm just a bit stuck now on what to look at. I'm sure Ive got mechanical resistance rather than an electrical fault.

[jukeboxmarty]

Hi Alan,

If the problem is mechanical, it would be rather difficult to turn the motor coupling (and worm gear) by hand.

If everything spins freely by hand (with the power off, in play position), it's not likely to be mechanical resistance.

Even if your motor capacitor tested good with a meter, that doesn't mean it's not failing under load.

I would remove the existing motor capacitor from the circuit, than temporarily try a new 1.0 MFD capacitor in the circuit to check the speed. I just use a regular 1.0MFD 630V capacitor for this test.

Hope you get it sorted out.

[alanj]

Thanks jukeboxmarty - I will try a different capacitor. I can turn the motor coupling and everything seems to turn smoothly, so looks like you are perhaps right.

[alanj]

ok so I disconnected the run capacitor and temp replaced with .8uf 250v capacitor (that’s the nearest I could find). This has speeded the record playing speed up, but it is still a bit slow. So my next question is: how sensitive is the speed to the capacitor value? And, is that why it’s still a bit slow?

[jukeboxmarty]

If the temporary .8 MFD capacitor makes the motor turn faster than your original, I would replace the motor capacitor with a new one.

The original value Seeburg supplied for motor capacitors (on earlier machines) was 1.4/1.0 MFD. They later changed it to 1.65/.75 MFD (same motor, same gears), so I don't think is extremely sensitive.

I'd try it with a (50hz) strobe disk to see how slow it's really turning.

[alanj]

Confirmed, no autospeed unit - the motor is connected directly to the 120v mains supply and also, of course via the 0.75 / 1.65 MFD capacitors.

The 0.75 is used in play mode and both are used for loading and scanning. Not sure why but I'm guessing more torque?

I have printed off a strobe sheet, so will work out how long it's taking to perform 45 Revolutions.

I have got the correct capacitor on order too.

[jukeboxmarty]

May 23, 2024 15:47:54 GMT alanj said:

The 0.75 is used in play mode and both are used for loading and scanning. Not sure why but I'm guessing more torque?

Yes, more torque (and less speed!).

[alanj]

the disc is playing at 42.5 rpm. I will test again once I get the correct value capacitor installed.

[jukeboxmarty]

May 24, 2024 8:40:46 GMT alanj said:

the disc is playing at 42.5 rpm. I will test again once I get the correct value capacitor installed.

It will be interesting to see your results!

[alanj]

Put in a 0.75uf cap - fixed, now running at the correct RPM. (To measure the RPM, I tried one of the strobe discs, which is more or less stable, but quit hard to see. So as well: I painted a white line on an old single B side, and counted the time for 180 revolutions. Came in on my stopwatch at 4 minutes and 01.34 seconds.)

[jukenorman]

Here is a link to a decent 50Hz strobe disc:

www.dropbox.com/scl/fi/6kuptakgmval1aoj18vy1/Strobe_45_50hz.pdf?rlkey=7p51inslo450vniyaq1yvnpts&st=uvfmfh74&dl=0

Print it off and fix it to an old 45. You will see that at 50Hz, the closest speed is 45.1 rpm. I'm sure you are aware that you need to view the strobe either with the jukebox fluorescent lamp lit or with some other form of mains powered light. Good news that you resolved your issue.

Norman.

[alanj]

May 31, 2024 10:00:11 GMT jukenorman said:

Here is a link to a decent 50Hz strobe disc:

www.dropbox.com/scl/fi/6kuptakgmval1aoj18vy1/Strobe_45_50hz.pdf?rlkey=7p51inslo450vniyaq1yvnpts&st=uvfmfh74&dl=0

Print it off and fix it to an old 45. You will see that at 50Hz, the closest speed is 45.1 rpm. I'm sure you are aware that you need to view the strobe either with the jukebox fluorescent lamp lit or with some other form of mains powered light. Good news that you resolved your issue.

Norman.

Thanks, thats a much better one that the one I found on t'web