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

[Gregor Anich]

Hello!

I checked the "I.D. Plate" - it is a 3700

Yesterday and today I was at the place where the machine is and we were 
looking at the connections and switches...

I do not understand what that override switch behind the basked is supposed to 
do, but when the machine is powered on and the override switch is moved, the 
override relay switches, so it seems to be ok?

We cleaned all the "latch switches" on the keyboard because they didn't make 
good contact. We used some sandpaper (only a bit) and WD-40 to clean them, 
now they make good contact.

There seems to be a problem with the letter switches on the keyboard.
If none of the switches is pressed the "input signal" should flow from the 
first switch to the second to the third and so on, and when one switch is 
pressed it is disconnected from the following switches.

But the "C" switch is broken (and maybe others) However I don't think that 
matters because there is nothing connected after the last switch "V" (to the 
contrary of the schematic)

For the number switches there is something connected after the "0", but those 
kind of work - there are about 140 Ohms accross all number switches when none 
is pressed.


Then we did the following to check all contacts between the keyboard and the 
accumulator:
 - put the accumulator into position "A1"
 - connect the DMM in diode/conduction testing mode to the chassis (GND) and 
signal 26 from the "TIMING BOARD" (lower right corner on Page 12F of the 
manual)
 - manually push the "latch arm" into the "latch solenoid" (like it was 
getting current) so the keyboard switches are latched and the "latch 
switches" are moved properly when a keyboard switch is pressed
- press "A" and "1"
- manually switch the "start relay" like it was getting current (to get signal 
13 connected to GND)

and we get a beep, with about 24 ohms resistance of which 23 come from the 
solenoid in the accumulator (which works if 12VDC are applied manually)

So the connection from the control box to the keyboard through the latch 
switches and keyboard switches, down to the accumulator through the magnet 
and back up through the keyboard from which it finally goes back to the 
control box (signals 13 and 16) seems to be ok.

Electronics are only my hobby so I am not really good at it.
When looking at the timing board circuit I am not sure what it is supposed to 
do.

The only possible path where enough current for the accumulator solenoid could 
come from seems through D6, signal 35.
Signal 35 is connected to the rectifier D31-D34 and I guess it should 
be -28VDC?

When I measure the voltage of signal 35 (before D6) on the timing board it 
says about 0VDC and 14VAC and 0VDC/AC after D6.

Any ideas? :-)

Thanks,
greg

On Friday 26 January 2007 18:36:44 Ron Rich wrote:
> I have two 3700 manuals--neither of which have a sequence of operation in
> them. I think that the last manual to show that was the 3500.  The model
> number of the machine shoud be on the rear of the cabinet on an "I.D.
> Plate". As  for your problems--I am guessing that either a switch on the
> keyboard is not "making", or there is an open in one of the plugs. The
> record holder basket rotation is controlled by the "override switch"
> located behind the basket. These are prone to not make contact. Check it 
> (as well as all keyboard contacts) with a meter. Ron Rich