[Jukebox-list] Missing part of Wurlitzer 3700 Service Manual

[Gregor Anich]

On Friday 02 February 2007 05:59:21 Ron Rich wrote:
> Answers in text, below, at (<)---Ron Rich
>
> The BO/AC case says "Model No. 555" and the CONTROL BOX case says "Model
> 3700 BO/AC"
>
>   <I think--not sure--"BO" stood for "Bonus", and "AC" for "Accumulator"
>

Yes, in the manual it is referred to as the "Bonus accumulator" in some 
places.

> The "diode board" in the control box has 141107 on the back but looks like
> part no. 138870 in the manual.
> The triac board has 140765 on the back but looks like part no. 140764 in
> the manual.
> < I believe that the number you see on the board is the number for the
> board only--no parts installed

Ok.

>
> I have traced the problem with the selection accumulator latch solenoid
> back to the rectifier D31-D34 on that "diode board" in the control box. It
> seems like it was broken and someone replaced it with an integrated
> rectifier, but he mixed up + and - so +28VDC and -28VDC were swapped.....
>   < Some times people do some strange things---Can be "fun" --once you find
> "it" !
>

Yes, hehe... there also was a 8A fuse in the control box which was blown but 
someone used some wire to bypass it... I replaced it with a new fuse.

> I fixed it and now the box behaves a bit different ;-)
>
> First of all, when I activate the free-play switch the selection
> accumulator doesn't start rotating immediately anymore, it starts when a
> letter and a number were pressed.
> Then the correct latch pin is released by the solenoid in the selection
> accumulator, it stops rotating and the keyboard switches are released.
>   < All above is the correct sequence of operation

What should happen as the next step? Should the magazine start rotating?

> Nothing else happens.
>
> The override and lock solenoids work, when putting the scan-load-run switch
> into the scan position and then switching the service switch the magazine
> starts rotating.
>
>   <does it rotate twice ? If so, the "override switch" is operating as it
> should.

I tried today and I think it was not stopping after two rotations. During the 
third rotation the 8A fuse in the control box blew but I think that was 
because I replaced the triac TR1. Gotta get some more of those fuses...

>
> When the scan-load-run switch is in the run position the magazine lock
> solenoid should get current from signal 71 which is connected with a 10
> Ohms resistor and 0.47 uF (?) capacitor in series to signal 64.
>
>    <Hint--Maybe--The "signal numbers" that you refer to above (71-64) WERE
> wire colors designators in older phono schematics--I don't know if that is
> still true on that model. If true #64 should be a yellow wire, with a blue
> tracer.
>

Yes, it is a yellow wire with blue tracer.

> Signal 64 comes out of the triac board from TR1.
> There's a override relay which is activated/swiched as soon as the jukebox
> gets power and which connects the gate of TR1 to GND when it is active (I
> checked that with the DMM)
>
> I measured the voltages on the triac board for TR1. There are 24VAC at
> input T1 and 0VAC at the output T2.
>
> My guess is that it is broken. It was replaced by someone with another part
> already which has "SSC TXAL 2210B 7822S" written on it - I did not look it
> up yet (too late) - the other, original triacs have Q2010L4 written on them
>
>   < I think that you have found the problem--
>

One of the problems. I replaced the triac TR1 by a good one, and when removing 
the old one I found out that it was really blown! (probably because someone 
bypassed the 8A fuse...) The TO-220 case fell apart (the cooling plate came 
off the device and you could look at the internals) - never seen that 
before ;)

I wonder if you have any ideas - there doesn't seem to be much connected to 
the output of that triac but I don't yet have any idea what might cause the 
8A fuse to blow/what shorts the output of TR1.

I hope the replacement which I used for TR1 was ok, it was a BT137-600 600V/8A 
triac from my cheap soldering station.
Is this a proper replacement for the original which was Q2010L4 I think? 
(200V/10A like the other two triacs on the triac board)

Thanks! :-)