424 Princess Royal, odd selections after C or D not working

[steve]

I've had the selector out and apart, everything is clean, and no resistance in any of the switches.  All selections work except for the odds after those two letters. Just continually searches (write arm carriage) until power is reset.  Have ohmed out the harness, and I get good continuity from each pin to various wiper rings and rivets. Except for one.  Had one pin that read like 80 ohms (meter was in diode range to get the beep).  All the rest read zero.  Not sure if that's my problem or not.  I tried, but there is so much going on in those wiper and contact diagrams I struggle to follow it.  I assume I have to be missing a connection somewhere.  About ready to get another selector off Ebay that looks worse than mine (mine is clean and shiny).  I think it has to be a connection inside the selector pancake itself, but I don't know.  I do not believe it's a bad wiper connection. I have cleaned and cleaned all that (out of the unit), with spring tension very good on each leaf.  Thanks.    Steve Preston

[jukenorman]

Hi Steve,
Your problem will most likely be with the C or D buttons, there are series links through them in their reset state. I think your method of testing is suspect, continuity testing of contacts with a digital multimeter invariably produces misleading results because of the very small current generated by the meter. A small battery and test lamp would give you more meaningful indications or an analogue meter if you have one - although I very rarely use mine because it's just so big!

Norman.

[Ron Rich]

Hi Norman,
BUY a "new", smaller, meter !!
Steve,
I agree with Norman here-- a digital meter will not show if a contact is able to handle current, even if on the "Ohms" range--. Didja READ, the above sticky on 400 series jukes ?
Ron Rich

[steve]

Thanks for the replies. I did read the sticky pertinent to my issue, and I do agree that analog meters are better to check for noisy or erratic switches, but to be honest, my Fluke 12 has never lied to me in 30 years. With repeated pressing of each switch and it comes up 0.3 each time or whatever it was, I have to call it good.  The keyboard contacts are as clean as I can get a switch. I took it back out last night and ohmed each contact in each letter and number in low ohms range, with no resistance. It's not a contact in the buttons.  I recleaned all the switches again, and even took a magnifying glass and inspected every wire link from from switch bank to the next, giving everything the wiggle test.  I really can't see it being a switch.  Tks.

[steve]

There isn’t any valid reason I can think of why I measured resistance on one pin of the selector harness. There aren’t any resistors inside it. Any continuity read from plug to selector at all should have been zero ohms, unless I was reading through the coil

[steve]

Ron, you were correct. I took the selector back off, polished all contacts with Mother’s until everything was shiny, cleaned that off, and rubbed De-Oxit into both sides with a rag. Biased all springs during reassembly (the shorter ones were not protruding out like they should have been). All selections working now. Thank you!

[Ron Rich]

Hi Steve,
Glad you found it-- I keep posting the fact that I am not always write, er, rite,-- er, correct--BUT, I am nevar rong ! Ron Rich

[pughwee]

New to the site and thankful I found it. 40 years ago I worked on jukeboxes with my father but have probably forgotten more than I ever knew. I am having this same issue and knew I would have to work on the selector unit, which I vaguely remember doing once upon a time. My question is to Steve above, as to what "Mother's" is? De-Oxit was easy enough to find. Also not sure how to find and access a pertaining "stickie"