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Post by shrimpeater on Nov 10, 2022 1:54:57 GMT
Rockola 425 I can pick a selection and write in does the serarch,stop at number,and that's it.
The light downstairs comes on,but no hammer action. If I move a selection by hand,I get nothing also.
Not sure where to begin to look. Was told it might be missing the -28 volts,but where does that come from?
Thank you
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Post by jukenorman on Nov 10, 2022 11:02:30 GMT
The -28VDC comes from the power supply which is the unit shown on page 18 of the parts list, if you have one? The Rock-Ola service manuals generally gloss over the power supply unit. There will be two fused -28V rails. Remember that if the fuses are blown, they are that way for a reason!
Norman.
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Post by shrimpeater on Nov 12, 2022 3:36:36 GMT
Looks like I need to focus on accumulator coil,which activates the write in hamme,and wooble plate solenoid.
I got more from reading the "jukebox theory of operation" for this box,than I did looking at the flow charts in the manuel.
I guess we all understand things differently.
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Post by jukenorman on Nov 12, 2022 9:50:12 GMT
Well yes, of course you can focus on these items for your write-in issue because, as with any fault, you have to start somewhere! But that part of the write-in circuit relies on -28VDC to operate whereas the operation of the write-in motor (which you told us carries out the search OK) relies on AC power. You also said that nothing happens when you manually set a selection pin, another -28VDC circuit; hence the suggestion to check the DC power.
Norman.
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Post by shrimpeater on Nov 14, 2022 1:24:00 GMT
Ok. I pulled the power supply out.
What I don't understand is negative voltage. How and were would I check this voltage.
Other than the transformer,there is a rectifier and a set of contacts in unit.
Any help is appreciated.
Thank you
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Post by jukenorman on Nov 14, 2022 10:11:15 GMT
A DC power supply (or battery) has a positive and negative terminal. In a jukebox, the metal parts (referred to as ground or earth) are connected to one terminal of the power supplies, both AC and DC. This is referred to as 0V or ground. If the negative terminal of the DC power supply is connected to ground, the DC voltage is positive with respect to ground or 0V. However if the positive terminal of the DC power supply is tied to ground, the DC voltage is now negative with respect to ground.
If you use a digital meter, connecting the black lead to ground and the red to the DC source, it will read -28V. With an analog meter, the leads must be reversed to read negative DC voltage, ie red lead to ground. Does that make sense?
Norman.
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Post by shrimpeater on Nov 14, 2022 23:55:45 GMT
I do have a digital meter. I took readings off the rectifier and i'm getting -23. A little short of the -28.
I'm really not sure where to take the readings . I don't think the motor in the selector unit is working either.It must be -28 also.
So,If I can get the -28 from wherever to wherever,I'm sure I'll be in busisess. BUt at this point I'm just ready to push aside for now.
I was using the scan switch and realized the carraige wasn't going back to home...which I figured it should.
I went to check to see what my mAX does,and it's on the blink as well.It was working fine when I put it to the side.So,I'm going to start working on the MAX again since I do have schematics and troubleshooting manuel .If I had a wiring diagram for the 425 I could most likely figure this issue out.I just don't know where the -28 comes from from.
Thank you
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Post by jukenorman on Nov 15, 2022 11:18:26 GMT
You have previously largely answered your own question regarding where the -28V comes from - transformer and rectifier! I would recommend you get a decent manual.
Norman.
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Post by shrimpeater on Mar 18, 2023 22:29:53 GMT
I pulled the box out today to start troubleshooting.(again) Voltages look good.Box doesn't go home when first started. If I make a selection it will find it and hammer activates. That's it .Selection made,no action. Fuses checked
So I'm going into the manuel flow chart to see if I can figure this out.
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Post by jukenorman on Mar 19, 2023 10:23:57 GMT
Are you saying the carousel motor doesn't operate?
Norman.
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Post by shrimpeater on Mar 19, 2023 16:58:09 GMT
Correct. After making selection the limit lamp flashes as normal. No carousel movement. I though these machines where suppose to go to home once finished,or turned on when out of sequence. Checked wobble plate and switch In my manuel ( yes,I think I have a good one) it says that is what should operate and close switches once the selection is made.I actuaaly know that,but i"m in troubleshooting mode. However,not sure why it isn't homing. I'm pretty sure my -28 is there since the contacts on the stop relay and coil on hammer fires?
It doesn't scan with switch either. I'm going to look for the switch settings. I know the cam switches,but not this style,but right now all 3 closed.
Thank you |
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Post by jukenorman on Mar 20, 2023 11:12:39 GMT
When you operate the scan switch, is the play control relay energising (located in the power distribution unit)?
Norman.
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Post by shrimpeater on Mar 20, 2023 13:54:15 GMT
Yes. I also cleaned the contacts and made sure they worked properly.
I'm guessing the motor might have went out.
I have to fix this issue first of course,before going further. I'm hoping I have the same motor on 2 of the mechs I have for parts.
Thank you
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Post by jukenorman on Mar 20, 2023 15:46:20 GMT
Yes, the motor next - always worth servicing the motor anyway - although it's not yet guaranteed that it's a motor problem.
Norman.
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Post by shrimpeater on Mar 21, 2023 0:51:57 GMT
Not a motor problem. I swapped motors. Used a known good one from that 437 I was working on.Same model#. Nothing
When I put machine in scan,the turntable spins,and that's about it
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