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Old May 17th 10, 08:02 AM posted to alt.collecting.juke-boxes
Rob in NYC[_2_]
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Posts: 103
Default Write in problem: Seeburg L-100

John, These models were notorious for edge connector problems (you've
heard this I'am sure).

From what I recall, this particular printed stepper requires that both
stepper wipers be at "home" position and making good contact with a
contact at that position in order to pass the write-in pulse from the
keyboard. The purpose of these contacts is to remove the pulse from
the keyboard while the stepper is receiving. The older and later
machines used contacts(which I eliminate) on a timing relay for this
purpose.

You should be able to test for stepper write-in by tapping out a set
of pulses by shorting the wallbox signal line to ground.

Also, IF this unit has a test link in the write-in circuit you should
be able to open it and with power off, connect your meter to the
contact that goes to the write-in contacts on both the stepper and
pricing unit. If there is no such link on your unit, connect to one
side of the write-in contacts (you'll have to try both) and the other
side to chassis ground.

Then with power still off, try pressing both a letter and number on
the keyboard and see what reading you get, you should use a meter
scale that can measure at least 5k-ohm because there are resistors
that will bring the to-ground reading to at least that amount.

The write-in goes first to numbers then to letters then to ground by
way of a 4 point 7k-ohm resistor. BTW: have you tested the resistors
in this section. If you have an assistant, have them hold down the
buttons while you jiggle the edge connectors at the stepper and tap
the stepper wipers and relays to check of any change in meter reading.

The printed boards on both stepper and tormat power unit
(TEU1)sometimes suffer from carbonization which bleeds away the write-
in current, I have had to eliminate the printed foils and do point-to-
point as well as eliminate the edge connector on these boards. You
have done voltage readings that appear OK so this is unlikely to be
the prob here.

I have had two L-100s and one K (200) the latter went into commercial
service and rather than dealing with the board problems which include
burning up, I modded that machine to use a 201 back door. Frankly,
although the L and K are favorites of mine they are a PIA to deal with.
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