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Post by bonnie59 on Jan 19, 2021 12:43:45 GMT
Hi There,
I have a Rockola 1475 that has not long been restored and when in any category the machine will not register any selection from button 14 - 40.
I have removed the keyboard button slider contacts and carefully cleaned all of them with deoxit. I have checked that the sliders are making contact when fitted in the machine and the buttons are pressed.
Based on the that fact I get the same issue in all categories (and after looking at the schematic in the manual) I don't think it's category switch related? I am coming to the conclusion it must be pin bank related . . O am looking for any thoughts on what else I should check before a serious disassbly is umdertaken.
Many Thanks
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Post by jukenorman on Jan 19, 2021 14:26:29 GMT
These sort of problems and "recently restored" don't hang well together! You should check the Jones plug/sockets to the button bank and the selector assembly. Inside the accumulator assembly there is a set of contacts, make sure they are clean. Also in there is a dual can capacitor, has it been changed - the 300uF section provides the pulse to the selector coils? Finally, check the 28V DC.
Norman.
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Post by Ron Rich on Jan 19, 2021 14:26:58 GMT
Hi Bonnie,
Try the following--
Make EVERY selection--If NONE of them fire a pin, the likely-hood of it being in the pinbank, is very low, IMHO. I am not familiar with that system, but I would look for a blown fuse, or a broken (ground) wire -- Is this phono new to you--has it been working an just quit-- has it been moved since it ran last ? Ron Rich
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Post by bonnie59 on Jan 19, 2021 21:00:27 GMT
Thank you for the responses, much appreciated.
Juke was delivered to me restored coming on for 12 months ago and hasn't moved. Buttons 31-40 were intermittent for a while a couple of months back but once "warmed" up would start working again.
Now not working along with 21-30 and 14 - 20.
So some selections work.
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Post by bonnie59 on Jan 19, 2021 21:03:36 GMT
These sort of problems and "recently restored" don't hang well together! You should check the Jones plug/sockets to the button bank and the selector assembly. Inside the accumulator assembly there is a set of contacts, make sure they are clean. Also in there is a dual can capacitor, has it been changed - the 300uF section provides the pulse to the selector coils? Finally, check the 28V DC. Norman. Pretty certain Capacitor hasn't been changed. Would you expect this to have been done? Will also check the contacts in the accumalator. Where should I check 28V DC? Thanks again. |
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Post by jukenorman on Jan 19, 2021 21:53:32 GMT
The 300uF capacitor is important because that is discharged through the reset relay which in turn operates the set of contacts in the accumulator assembly to make the selection - and you want a good solid pulse to pull in the selection coil. Change it for a new 330uF or maybe even 470uF. You can check the 28V DC at the 150uF capacitor, the other section of the 300uF. You could change the 150uF, not quite so important but removing the dual section capacitor would free up space for new capacitors.
Norman.
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Post by Ron Rich on Jan 20, 2021 0:25:34 GMT
Bonnie,
If the cap is a dual cap in one can, chances are it has not been changed, and they do have a history of failing ! Ron Rich
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Post by juke46 on Jan 20, 2021 11:56:31 GMT
I have a Rockola 1478. It suffered from random and intermittent problems of not pulling some of the pins. I finally ended up removing the dirty appearing pinbank, disassembling it and cleaning every piece. The interior of the pinbank was rather dirty but, much less than the exterior. With all the pieces (many small parts) making up the pinbank I purchased a spare one from Bill Butterfield (Musical Fun For Everyone). I just knew I would lose a piece or two and it would be nice to keep an extra for spares. Amazingly, I managed not to lose anything with my clumsy hands and lousy eyesight. Final assembly was difficult but possible. It has worked perfectly since. It was not the easiest job in the world. I do wish I had replaced that dual capacitor first. I shall look into that now even though the machine has performed flawlessly since cleaning the pinbank. Seeburg pinbanks are much easier to do than the Rockola round one was (for me).
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Post by bonnie59 on Jan 20, 2021 12:12:57 GMT
One piece of information I have failed to give is that whatever selection button I press the magazine will always start scanning. Looking at the schematic this must mean that the capacitor is pulling in the reset coil? . . . . . .it's just the selector pin that doesn't then fire.. . . .
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Post by Ron Rich on Jan 20, 2021 14:04:28 GMT
Hi Bonnie, and David,
I do not have the schematic for that model, but judging by what Mr Rockola, once told me*, and what I know of Seeburg's systems, I would guess the scan control add coil receives a "24 VAC" direct pulse when-ever any button is pushed. This MAY, or MAY Not come directly from the keyboard, or it may come from the pricing unit's relay being energized ?
* with a wink---"we used the same engineers-- only old J.P did not know it". Ron Rich
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Post by jukenorman on Jan 20, 2021 15:22:57 GMT
Yes, I wasn't suggesting that the reset coil wasn't being energised - but the length of time it remains energised is determined by the charge in the 300uF capacitor. And the size of pulse being delivered to the selection coil is determined by how long the reset coil is energised (milliseconds matter!). So if the capacitor is failing (and if it's original, it's over sixty years old!), the pulse is consequently poor - but not non-existant.
Replacing a capacitor is much more straightforward than stripping a pinbank so I think it might well be worth a try.
Norman.
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Post by Ron Rich on Jan 20, 2021 15:56:56 GMT
Hi Norman,
Thanks for clarifying that ! Yep, changing that dual-cap is, much easier, then working on that pinbank ! I have seen people become confused by the can-- remember the neg's of both caps, are common, inside that can. Ron Rich
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Post by bonnie59 on Jan 20, 2021 20:18:23 GMT
Hi Norman, Thanks for clarifying that ! Yep, changing that dual-cap is, much easier, then working on that pinbank ! I have seen people become confused by the can-- remember the neg's of both caps, are common, inside that can. Ron Rich Sound reasoning Norman, thanks very much indeed. It does make a lot of sense and certainly a simple place to start on a component that should be replaced anyway. I see you are based in the UK. Where would you suggest I try to get a replacement dual-cap? |
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Post by jukenorman on Jan 20, 2021 22:07:36 GMT
Hi Bonnie59,
Although a much better selection of multi-section capacitors is available in Europe than the US, I'm 95% certain you won't find 300/150uF. You will have to install two capacitors, 330 and 150uF and common up the negative leads. Capacitors these days are physically smaller than sixty years ago, so you will have no issue fitting them in. I normally buy my capacitors in bulk packs but on occasion I buy from Cricklewood Electronics who will supply single units - but buying two capacitors (total cost 90p) from them might not be cost effective because of shipping charges. On the odd occasion that I need something desperately, I usually buy from ebay. Make sure the voltage rating is 50V although you might get a betetr selection at 63V.
Norman.
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Post by Ron Rich on Jan 20, 2021 23:41:26 GMT
Hi Bonnie,
Please mark your signature area with the country you reside in. Thank you, Ron Rich
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