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Post by jukenorman on May 15, 2022 21:01:11 GMT
Hi Pete,
Yes, you have the -28VDC at the start and we are making it to WI sequence 10 so it's unlikely to be a power supply issue, in my opinion of course. Actually the K2-1 test you have just done is really good news because it eliminates so much. But we still haven't nailed it - more thinking required!
Norman.
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Post by prime on May 15, 2022 21:05:50 GMT
I really apricate your help with this. thanks pete
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Post by jukenorman on May 15, 2022 21:34:43 GMT
Try the card procedure on the normally open contacts of the stop relay one at a time, see if any of these stops the DC voltage dropping. If that does stop the voltage dropping, we can always identify the culprit later, there will be a diagram in the manual showing which contact is which.
Norman.
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Post by prime on May 15, 2022 22:14:02 GMT
OK, These are my findings, stop relay 5 switches, 3 at back 2 at front , back first, top switch card no change write in wont stop, second switch ,-7.2 vdc, 3rd switch -6.8 vdc. front top switch no change write in will not engage, second switch -6.8 vdc. Something else i just happen to notice ,voltage drop when carriage starts spinning -12vdc. this might explain why the carriage spins slower than my other Rockola, i thought it was because it was an older tube model. Just a thought can any part of the selection assembly cause a voltage drop, it is one area we have not looked at?
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Post by jukenorman on May 16, 2022 8:51:20 GMT
Hi Pete,
The write-in carriage is operated from 25VAC so that shouldn't have a direct effect on the DC voltage. I think we may be getting to the limit of what we can do here, I think this is now probably a job for an experienced tech.
There is one other thing you could try. There is a second -28VDC feed for the read-out circuits and motors that is supplied from the same rectifier. It has (should have) a 1.6A fuse. You could pull that fuse and see whether that restores the voltage to the WI DC. We might be barking up the wrong tree - there may be a read-out fault that's pulling down the DC and that is having a knock on effect to the write-in circuits.
Norman.
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Post by prime on May 16, 2022 11:42:47 GMT
Would that fuse be one of the fuses on the power supply?
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Post by jukenorman on May 16, 2022 13:31:53 GMT
Yes it will be but I cannot identify it any further. The -28VDC supply wire to the read-out circuits is purple if that helps in any way. I'm beginning to go off the idea that it may be on the read-out side anyway. I seem to recall you saying that the read-out section works OK? But worth a check, I suppose.
Can I clarify, when you said "carriage" above, you do mean the write-in carriage aka write-in arm and not the record basket?
Norman. |
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Post by prime on May 16, 2022 13:54:55 GMT
No im speaking about the basket,
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Post by jukenorman on May 16, 2022 14:30:56 GMT
OK Pete,
Try removing the read-out DC fuse anyway and see if that has an effect on the write-in process. As I've said above we're getting to the point where in order to make further progress, I would really need to see what's going on with my own eyes and to be able to check things out.
With regard to the carousel motor pulling down the DC voltage, had you serviced the motor?
Norman.
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Post by prime on May 16, 2022 14:34:34 GMT
Just oiled shaft etc, it turns fairly easy. Should i remove and rebuild.?
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Post by jukenorman on May 16, 2022 15:59:31 GMT
Hi Pete,
That's what I would have done. It's a 56 year old jukebox after all. By servicing the motors etc up front, if I was then to see an issue where the -28VDC is reading -12, then I would know that the motor itself shouldn't be the issue because I have fully serviced it! I think we have probably taken this as far as we can, if not further! There are now too many unknowns to be able to make reasonable judgements on how to proceed.
Norman.
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Post by prime on May 24, 2022 18:49:34 GMT
Hi Ron and Norman, I have a question that im sure either one of you will know the answer to. If i read this correctly, when the write in wiper blade reaches a live contact and segment, a break is applied to the carriage motor ,then a hammer coil operates moving a selector lever into play, this engages the wobble plate switch. In my case when the write in stops, it does not push down the lever but the wobble plate switch engages and vibrates. Am i correct in thinking that switch should not get power until lever is moved?
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Post by jukenorman on May 24, 2022 21:42:36 GMT
No Pete, you are not correct! What happens is explained in the manual in the accompanying text to WI Sequence 10 and I also think that we may have covered it in previous replies. WI Sequence 9 deals with the WI indexing, braking of the Write In Motor (not carriage motor) and the energising of the Stop Relay K4. Sequence 10 goes on to say that a contact of K4 energises the Wobble Plate SOLENOID (which in turn closes the wobble plate switch). The same contact of K4 energises the Accumulator Reset Coil which in turn operates the switches K2-1 and K2-2. This is the point where we were losing the will to live! Anyway switch K2-1 operates the WI hammer coil and K2-2 operates the ADR Relay on a time delay to produce the fat pulse - remember? We had ascertained from measurements you took that something is pulling down the DC voltage. I would suggest that you read back through this thread and study the "friendly" manual!
Norman.
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Post by prime on May 25, 2022 21:15:56 GMT
Ive been thinking about my two voltage problems ,ac and dc and have taken a photo of the rectifier, i think half of the rectifier is gone. If you a agree can you direct me to what i would use to replace it. thanks pete  |
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Post by Ron Rich on May 25, 2022 23:24:27 GMT
H Pete,
Can you smell it-- smells like rotten eggs ! DO NOT power up that unit till after, you replace that whole rectifier. That's probably the result of the 2 amp fuse ? You have the schematic-- read it--and figure out what you need to replace it, with. Ron Rich
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