HF100R randomly blows F4

Greetings all,

Working on this unit for a friend of mine. Everything has been recapped and seems to be working well other than occasionally it will blow the 1A slo-blow fuse(F4) on the selection receiver. I've eliminated the CCU by unplugging it and making selections with the wallbox and I still have the problem. I believe that's telling me the problem is either in the electrical selector or the selector assembly. Once this is resolved, I can button it up and reclaim some space for MY 100R.

Thanks for any suggestions!

-Jim

Hi Jim,
You have one, or more, shorted/"overheated" coils in the SA Unit--
Ron Rich

Thanks, Ron. I'll start checking them. It'll be easy enough to find out, but do you roughly know the typical resistance of a good coil?

-Jim

Hi Jim,
Nope-sorry I don't recall the resistance reading of those coils--I have not taken an ohm meter to them in 40 years--I use an Amp meter, and watch current draw, when checking them. (1.5A, is the normal reading, on primary winding of the transformer). Ron Rich

Ron,

Of course, you were absolutely correct. There was a single coil out of the whole pinbank that was toasted. It only took me 5 months to get back at this thing, but I finally decided to get hard core with it. For any future reference, the resistance of the coils are about 3.4 to 4 ohms. The bad one was 0.4 ohms. And while I was certain the fuse blowing was a random occurrence, there was actually a test record in the slot with the bad coil.

I have a lot of respect for the assemblers that put these things together back in the day. As everyone who's messed with these will know, you have to take the whole pinbank apart to get to the bad coil. Ultimately I replaced the entire section of coils since I had a known good set. Seemed like it would be easier than trying to get just one coil out. It was necessary to do the de-tarnish procedure as well. Time consuming, but it had to be done. Decided to degrease the mechanism, too, since I was already most of the way there. Again, not as bad a job as I was anticipating. As Ron suggested in his book, I let the unit dry off on a hot California afternoon on the tailgate of my truck.

Everything is cleaned and lubed and back together and the mechanism is back in the cabinet. Seems to scan fine when using the service switch. I manually added some credits and tried to select a record, but the mech wouldn't move. Then I remembered the 1A fuse was still blown from the bad pinbank coil. Duh! Changed the fuse and tried again. This time, after making a selection, the mechanism started scanning to the left. As soon as the reversing switch hit the stop, it blew F2(2A slo blow). The fuse was vaporized, not just popped. Grrrr! All that work and all I got was changing which fuse blows. All the switch contacts have been burnished and cleaned with DeOxit. Looking at the schematic block diagram, it looks like it's either the motor, the motor capacitor, or the .1 uf cap. Seems unlikely these would fail right at that moment, but who am I to say? It's old electronics.

Removing the .1 is easy enough, so maybe that's my first attempt. As I recall, Ron mentioned it being a good idea to disconnect/remove it anyway. I'm open for additional suggestions.

-Jim

As soon as the reversing switch hit the stop, it blew F2(2A slo blow).

Jim, this is a simple matter of the reversing switch's motor contacts not breaking-before-making. If you look at the mech schematically you'll how this throws a dead short across the AC mains.

Removing the .1 cap is a good idea also, but they usually "pop' if shorted.

Rob-NYC

Well, guys--maybe not so "simple"--
1. F-2 is NOT supposed to be a 2 A, SB !
2. It MAY be the switch is not opening before making, or,
3. The "bracer blades" are bent un-evenly causing the blades to "torque', and/or, over travel.
4. The above can be caused by either a broken/missing ( or on later models, miss-adjusted) "Rubber Bumpers", or a faulty motor run cap or add contacts.
Ron Rich .



















umpers"

Ok, here's the latest update: I removed the .1 cap and rechecked the reversing switch contacts. It looks like one blade might have been a bit tweaked, so I readjusted it and carefully moved the phenolic connector bar back and forth. All contacts look like they are breaking before making. I also replaced F2 with a 3A non slo-blo fuse. How the wrong one got in there, I'm not sure. It's one of my brand, so it must've been me. I also went thru the CCU again. I had forgotten to clean the solenoid plunger and it was a bit grimy. I also double checked all my switch contacts and gave it a final lube.

It's all back together and everything seems to be running well as far as the main jukebox is concerned. It sounds great and played all six of the records I selected. The keyboard response seems to be super quick when making selections. I need to populate all the record slots now and make sure they all play, front and back.

The last problem I have is when making selections thru the wallbox. It seems to be blowing F4 again, which I believe is telling me the pulse to the selector coils is staying on too long; similar to when the CCU is gummed up and slow to release. Best I can tell is that pulse comes from Timing Relay #1 in the WSR. I re-cleaned the contacts on all the relays associated with the stepper unit and relubed all the sprockets, cogs, etc. I'm watching the relay while making selections on the 3W1. It looks like worst case(longest pulse train), the relay only pulls in for about a 1/2 second. I wouldn't think that'd be long enough to get the selection coils upset.

Once I'm past this last hurdle, it's some final clean up and detailing and it can go back to my co-worker's living room. Then maybe I can start working on my own HF100R. I've certainly learned a ton off of this one. Frustrating, but a very enjoyable project.

Rob/Ron, I can't thank you guys enough for helping out!

-Jim

Best I can tell is that pulse comes from Timing Relay #1 in the WSR

Jim, I'll go through the last part of the stepper sequence. During the last series of stepper pulses, two sets of contacts riding on the number clapper close at each downstroke. The set nearest the hold magnet keeps that held down and charges the timing cap for it. The other set pulls-in the #1 timing relay which in-turn also pulls-in the #2 timing relay.

Both timing relays have copper slugs that serve to hold them in for a period when no power is applied. In #1 that keeps it down during number stepper advances. After the last number step timing relay #1 falls out but added rings on #2 hold it in fractionally longer. The write-in pulse happens in this condition.

Summing up in order to write-in: Both latter and number wipers must be on rivets. Both timing relays must be pulled-in during the number train. After the last number advance timing relay #1 falls out and # 2 right behind it followed by steppers homing.

Something to check:

-Is #2 staying in longer than a fraction of a second after #1 falls out?

I come at this from the standpoint of later, Tormat operation, but stepper sequence is the same. The only real difference is that a too-long write-in pulse would not cause any damage on the Tormat.

I suspect that you may still have a bad coil(s) in the pinbank. Those coils were nowhere near as robust as they should have been and Seeburg should have designed an R-C voltage supply to limit the duration of the pulse. A resistor and large capacitor would have prevented burned coils. Alternately, Wurlitzer and 1960's Rock-Ola's used lightbulbs to limit current.

Rob

Hi Jim,
Have you checked the relay contacts-burned/pitted, or incorrectly adjusted contacts, will "blow that fuse"-- Ron Rich

All the stepper contacts look pretty good, but there were a couple sets of contacts on the various relays that needed some adjusting. I burnished everything again and everything looks pretty good. Transfer relay #2 does drop out a split second after TR #1, so I believe that is working correctly as well.

I reinstall everything in the next day or so and give it a try. I will also recheck the pin bank for any more bad coils. Jeez, I hope not!

-Jim