Wurlitzer 3700, Latch solenoid chattering away

[stevet]

Got this box for free, been "serviced" by several others and I'm going through all its problems one by one. I have the manual, I'm a retired consumer electronics technician, with 55 years experience. My first question on this site!! I've been through the adjustments on the latch switches, the box has been set to free play. As soon as the box is turned on, the setup relay and the latch solenoid start chattering away. The service manual I have only shows two diodes in the circuit. But this unit has a third diode on the same terminal strip, which seems to be wired in series with a terminal on the latch solenoid switch. Is this a revision my manual doesn't have? I'm not totally a novice on jukeboxes, I have my pride and joy 2200 juke in my living room that I keep running!

[jukenorman]

Look at Wurlitzer Service Bulletins 381 and 381-1 which you can find here www.flippers.com/Wurl_USA.html

Norman.

[stevet]

Thanks! Apparently, this box has had the upgrade installed before some time ago. The added diode on the terminal strip looks burnt so that's the first thing I will check! Thanks again for the info! 

[phillg]

Welcome to the forum!

Please let us know how you get on - it's always helpful for others searching to know how you fixed your juke!

Cheers,
Phill

[stevet]

I'm not sure whether to post a new thread or continue with this one as far as updates on my "progress" of fixing this box! I'm tackling the chattering latch solenoid first of the many problems this juke has. So far, I've found a shorted TR2 transistor on the timing board inside the BOAC box. Most likely caused by the protection diode across the transistor had come loose from its solder connection. The transistor is a high voltage spec one, that a ECG/NTE 287 transistor should be a good substitute. Had to order that one! Will update my progress whenever the part comes in! While waiting for the transistor, I went ahead and replaced the electrolytic caps inside this BOAC box. They still checked good after 50 years but changed them anyway!

[stevet]

Here's an update so far. Replaced the shorted transistor TR2 in the timing board and resoldered the loose diode on that board. The latch solenoid doesn't chatter anymore, but guess what?! It doesn't latch at all now either! Back to the schematics to figure out that relay 1 has to be energized to turn on the latch solenoid. Following the circuit paths to the relay coil I discovered that all of the record selection switches have a circuit path in series with the relay coil. In other words, if any of those 30 switches has a dirty or bad contact, there's no latch solenoid action! I read somewhere that you are not to use any type of contact cleaner on these switches but I did anyway! And now the latch solenoid works!. So, the box does take selections now but the record magazine doesn't turn and the thing just plays the same record over and over. So, to figure out what's the cause of that next!

[jukeboxmarty]

Thanks for reporting back!

It looks like you've made great progress!

As far as contact cleaner, sometimes it seems to work wonders. But a lot of the time the results are temporary. The way I figure it, if the spray doesn't work you could always take things apart to do the job right... as long as the cleaner doesn't leave a residue.

When I do work for customers I like to do it right the first time. 

[stevet]

Doing some more troubleshooting of the playing same record over and over symptom. Checking the microswitches on the side 1 and side 2 readout switches, the side 2 switch checked open. These are NOT ordinary microswitches! Drat, and no longer available anywhere that I can find. I've had luck in the past of taking a microswitch apart and burnishing the contacts, but this one has the shaft sticking out of the side, and I didn't want to risk damaging the pin sensor lever that's attached to it. So I drilled out one of the rivets holding the switch together and prying the switch halves apart far enough to squirt some cleaner inside and let it dry out for awhile. (Sorry, jukeboxmarty, what else can you do?) The switch seems to be positivity switching solidly like new! Hopefully it'll last quite a while, until somebody decides to resume production of these weird switches that Wurlitzer has! I'll post an update after reinstalling the switch and see what else is wrong! 

[stevet]

Another update! The jukebox is presently working almost like new! In total the Side Two switch on the rotating arm was open. NLA but was able to separate the halves of the switch enough to squirt some various cleaners in there and exercise the switch a zillion times. Seems to work pretty positive now. And the lock solenoid switch was also open, there are replacements available for that switch but for now I just took that switch apart and burnished the contacts, seems ok for now. And then there was a shorted transistor in the BOAC box, most likely caused by the protection diode across the transistor broke loose from the circuit board. Finally, when all was said and done, the thing was just constantly playing the same record over and over nonstop even though the pin was cancelled. This turned out to be one of the terminals of the lock solenoid was off, quite possibly caused by me when I pulled the chassis out to prop it up, the wires are right behind the chassis corner. Last thing I need to do is find a replacement fluorescent tube for the record listing thing. It's an oddball size. Here's a tip for checking the side 1 and 2 switches on the rotating arm and the contacts and so forth, measure with the power off, terminals 1 and 10 of the chassis plug with an ohmmeter, should be close to zero with the mechanism in rest position.

[phillg]

That's awesome to hear - I'm glad you got it up and running and there's nothing as satisfying as knowing "you did that"!

I just bought fluorescent tubes for my 2400 and Seeburg Model B from buylightfixtures.com (website looks suspicious but they're real people - I called to check ) Arrival isn't the fastest but they're not wildly expensive and they have a good range of strange tube sizes.

The tubes are considered an oddball size now, they're used exclusively in jukeboxes and older vending machines so they're getting harder to find. You can get LED T8 replacement for most sizes that are compatible with the starters and ballasts in these machines, but they're usually one-sided, so one side of the tube doesn't produce light. For some machines that's OK, but for my current two that's a non-starter since the tubes light up the title cards and also the lower display.

Cheers,
Phill