Help KD200 will not select

[robnyc]

Mauro, if you still have correct voltages with the peripherals connected the next steps are simple continuity tests.


With power off and credit unit disconnected, measure from the cathode of the W-I diode and chassis ground. This reading -if any is the background resistance which will be added to the readings we are going to take of the continuity from that write-in source through the interrupt contacts in the stepper and two trips through the tormat.

With the meter connected as above. press both a letter and number key at the same time -starting with A 1. If proper continuity, you should see a low resistance route to chassis ground. Note that during this point in production, Seeburg placed the 190 ohm thermistor in the tormat itself -so expect that value added to the meter reading.

As you seen, the W-I voltage is circuited through contacts in the stepper wipers and (IIRC) the relay there. The edge connectors are a known problem, but cleaning usually fixes that.

You don't have to go through all 200 letter-number combo's -just do A1-B2-C3-D4, etc.

If you find a lack of continuity at any point it is time to open the keyboard. The series circuits are fairly obvious there.

Let us know how it goes.

RobNYC

[mauro]

Rob, thanks for the method as I have never seen that before.
From cathode of WI diode to chassis ground I get 14K ohms.
All selector combinations show between 180 and 190 ohms resistance EXCEPT anything with the #9 , that remains at 14K ohm.
Would this be responsible for ALL selections not working?

[mauro]

Ok, I found the broken wire for the #9 button and soldered it in place.
Tried it and still no selections. The resistance to the WI diode is now the same as the other keys, about 180 ohms.
Sigh...

[robnyc]

Mauro, sorry for the delay in getting back here. It looks like you have good continuity through the keyboard. I did have one case in late 1989 where a VL had a sluggish linkage in the trip mechanics. It would miss the first few selections and then work correctly from then-on.

To find it I made several random selections and watched the trip 2050 (I still used them back then) when the mech scanned, the tube did show the typical brief purple flash when the slot was read out. Repeated oiling and a check of the trip coil position got things reliable.

I am puzzled by the 14k-ohm reading. With no C.U. and no kbd connected there should be near-infinite reading from cathode. From the anode, it would be approx 150K-ohms.

RobNYC

[mauro]

Hi Rob,
Thanks for the info it will be very useful in future troubleshooting!
I got the read out sorted out and the trip working properly but had to stop before fixing the write in as my friend decided to sell the juke, the buyer took it as is so I didn't continue, I would have really enjoyed figuring this one out but he had to deliver the next day.
Oh well, I'm sure there will be others.
The tough ones always seem to gravitate towards me!!
Thank you for your direction, I learned much about the KD!