Hello!

[johndaniels]

New here today. 

I'm slowly getting a Rock-Ola 445 (EU 220/240V model) back operational for a friend after decades of neglect and disuse. It is located at my friend's house a few miles away so I have only occasional access to it.

So far I have:

1. acquired the 444/445 service manual

2. discovered that the 25V AC 3A fuse had been removed, so I replaced it

3. with the fuse in discovered the gripper motor was getting very hot!

4. freed off and lubricated the gripper mechanism causing no. 3 above and hence the reason for the missing fuse

5. repaired a broken section of the read-out carriage Bakelite moulding around where one of the reset hammer mounting screws was

6. gently cleaned the contacts of the A and B lever detectors on the read-out carriage, and all the wiping contacts

7. rewound one of the carriage hammer reset coils which had previously been rewound by a previous owner/tech but with far too thick enamelled coper wire (0.25mm diameter) giving only 15 ohms DC resistance instead of 50 or so. I used wire half that thickness but evidently too much of it as the DC resistance is now 125 ohms, but it seems to work. I may redo it again with slightly thicker wire to try to get it closer to what it should be. I didn't want to risk damage by opening up the working one to measure the wire thickness.

8. now I've got it to play something I've found that it will now only play side B of any single - the read-out mechanism spins incessantly looking for an A-side selection (the write-in mechanism/circuitry works properly and sets the levers). It's probably going to be the A-B snap switches not changing over due to a gummed up dog, now that I've done a little research and watched various videos on the matter since last working on the machine, so that'll be my first action when I next visit.

9. found that the right hand channel of the amplifier is dead. A simple listening test reveals no hum in the right speakers but I need to trace through the circuit diagram to see where the signal stops. Hopefully something easily replaceable and not unobtanium. I will work through testing the transistors as necessary. In case I need any, if anyone has any suggestions for suitable replacements for the two op-amp chips and the power transistors I'm all ears. Hopefully the circuit schematic in the manual represents the 47160-A model fitted to this machine.

10. replaced the turntable motor rubber grommets at the motor was sagging to the point where it played at 33 1/3 rpm instead of 45 rpm.

If anyone has a copy of the power supply schematic I'd be most grateful. It's the EU 45750-1-A 220/240V AC version. I'm hoping that as most of the machine works, the power supply itself is fine. I'll check for any dodgy looking capacitors throughout and replace as necessary.

Cheers all.

UPDATE:

The A-B switch mechanism was indeed all gummed up and not swapping over at each full turn of the basket, so has been cleaned and lubricated and now working reliably.

Whilst my rewound hammer reset coil worked fine out of the machine, in use it didn't have quite enough power to actually reset the A levers, so I rewound it again in 0.16mm enamelled copper wire (size was an educated guess) which got me to 53 ohms but with rather more turns than I thought it would need so the overall diameter of the coil is a little larger than anticipated but still within the physical limits of the mounting frame. Hope to install in a couple of days to test, but have also purchased a used carriage with known good coils on ebay which should arrive later this week, just in case it's needed. For future reference if I was to rewind another one sometime, I would suggest 0.15mm wire.

The missing right channel audio was down to a (very) dirty volume pot and a dodgy connector, both of which have been sorted, so thankfully no dead electronics. Quite a relief!

Almost there!