Continental AMI Juke Box Fault Finding

[rob1948]

Thanks Guys !!!

[rob1948]

Hi Norman/Ron,
I replaced the 0.047uF capacitor on the Sprag Relay. I replaced the 100uF and 0.047uF capacitors on the 'Terminal Strip Assembly' in the Search Unit, which I assume are for the Pulse Control Relay ? The replacement capacitors are minute compared to the old ones being replaced (and I understand that capacitor technology has advanced in the last 50 years). However I switched on and still the selection solenoid and 2 x scan magnets in the scan control unit did not operate. I manually operated the magnets and pushed in a record selection pin and all was good. I did this manually once or twice and then the 100uF capacitor exploded ?? The old capacitor's one end was marked + but the new capacitor had no polarity marking and the supplier I bought the capacitors from said polarity did not matter The new replacement 0.047uF capacitor also with no polarity marking survived ? I have an old spare Search Unit but with no 0.047uF capacitor in the 'Terminal Strip Assembly' but a resistor in its place ? Should I replace my 0.047uF capacitor with a resistor ? I am battling with this last stretch of trouble shooting with the Pulse and Sprag relay. Please any suggestions. Thanks Rob

[Ron Rich]

Hi Rob,
You have me confuzzed?-- never saw a "paper" cap with a "+" mark-- Electrolytic type, sure-- and they MUST be connected correctly ! Older paper types had a band on the "outside foil" end-- which is supposed to be the "most negative" end. What was the voltage rating on the original, and the new, exploded one ? What does the schematic/parts list say should be there ? Ron Rich

[jukenorman]

Hi Rob,
The 0.05uF capacitor on the sprag relay is not critical to its operation (suppression) so don't get overly hung up on it (unless it has shorted of course)! Are you sure it's a resistor on your spare unit; some old capacitors can look very like resistors with similar colour banding?

The 100uF capacitor is however critical to the operation, you will not be able to make selections without it!

Norman.

[Ron Rich]

Hi Guyz,
I had forgotten all about those old paper caps-- yes, color coded banding, similar to resistors was used, and I think AMi, used them. Ron Rich

[rob1948]

Hi Norman/Ron,
This is what I got from Mantech Electronics a local supplier and I sure he has sold me the wrong capacitors. The sale slip reads 'Capacitor ELECT AXL 100uF 50v (I assume this is an Electrolytic capacitor?). It does not say DC on the capacitor and it does not have + and - markings and the guy said I can connect it any way and this tells me it must be AC ? The other smaller capacitor reads 'Capacitor Polyester 47nF 630v P-15', again with no indication of it being DC ??. The capacity and voltages are correct as per the original where the 100uF 50v is marked DC and with + and - and the 0.047MF 600v has an orange band on the one end indicating 'most negative' as you guys have said.
Back to the supplier I go. If I do not come right should I not order the 100% correct capacitors from America ?? Thanks Rob

[jukenorman]

Hi Rob,
Yes it looks like you should have got an axial electrolytic capacitor. The convention these days with axial electrolytics is that the positive end has an indentation band around the capacitor and there are arrows pointing to the negative end. You might find that 63V electrolytics are more readily available than 50V and that would be OK. If you did get an electrolytic and connected it the wrong way round, it would pop. The polyester capacitor should be fine and 47nF is 0.047uF. I cannot believe that you would need to get a 100uF from the US!

Norman.

[Ron Rich]

Rob,
The supplier is correct in what he sent you, markings are OK -- if the item was supplied correctly--
That cap should have been OK--BUT you must find the + - indicators on it -- as Norman said- most today have the indent ring on the positive side--
if neither side, or both sides, are marked that way, its a "non-polarized" cap--not use-able to replace polarized style. Ron Rich

[rob1948]

Hi Norman/Ron,
Yes you guys are right I called the supplier this morning and he pointed out to me that the capacitor has an indent ring on the one side which is the positive side and an arrow pointing to the other end which is the negative side. I have installed another new capacitor 100MFD and have installed it correctly with the indent ring to the positive side.(I must have installed the other capacitor incorrectly with it popping on me !). I have sprayed the the relay contacts once again with DeoxIt 5 and will leave them overnight. Will switch on in the morning. Thanks for your help guys, much appreciated !!! Rob

[Ron Rich]

Hi Rob,
IMHO, Deoxit -5 is NOT for relay contacts-- clean them with a plastic safe, safety solvent--zero residue, should be on them ! Ron Rich

[rob1948]

Hi Ron,
Thanks for that and for picking up that detail in my post !!! Just as well I came and read your posts once more, I have not yet switched on the JB and will now clean the 3 relay contacts with plastic safe, safety solvent as you recommend before switching on. Thanks again Rob

[Ron Rich]

Rob,
Be sure that stuff has dried prior to switching it on-- it may explode, if wet/fumes are present ! Ron Rich

[rob1948]

Hi Ron,
Thank for warning !! I have cleaned the contacts with safety solvent and have not switched the JB on since cleaning them so they should be dry. I am procrastinating the 'switching on' being scared the relay issue has not been resolved. But I will keep you and Norman 'posted' Thanks Rob

[Ron Rich]

Hi Rob,
Didja read the FAQ's, here on "contact cleaning" ?? Ron Rich

[rob1948]

Hi Ron,