[COLOR=“Blue”]Any ideas as to what else other problems to look for? [/COLOR]
Try running diagnostics.
I would check the switch outputs from the keyboard with a meter.
Sometimes newer revisions of boards incorporate different diagnostic routines and this may be why your symptoms changed.
[COLOR=“Blue”]Is the replacement unit faulty?[/COLOR]
Cannot say but if the keypad checks out OK the odds are high that it does have a problem.
[COLOR=“Blue”]If the switches check out OK then does that mean the control unit is faulty?[/COLOR]
Not 100 % but is does put the control board at the top of the list as a possible cause. This problem is always a bit of a crap shoot so you are trying to narrow the odds.
[COLOR=“Blue”]Also does the fact that, with the old control unit, all the switches appear to light up when you touch them indicate the keypad is OK.[/COLOR]
It is a good indication that the keypad is OK if the keys light the correct lights and only the correct lights. But I thought you said they were not operating correctly in your first post.
[COLOR=“Blue”]Is there a manual the can demonstrate testing the keyboard?[/COLOR]
No but I may be able to explain it. The diodes (D’s) pass current only in one direction (into the arrow) so it makes a difference which lead (polarity) is where. Set your meter to a 2 K ohm scale.
As an example to check the China key.
With the black lead on P1-6 and red lead on P1-13 the resistance should drop when you push the China key.
The circuit path is P1-6 through D5 (diode) through SW14 and out P1-13.
You may have to swap the meter lead locations to get a reading, it depends on the meter.
[COLOR=“Blue”]It may be worth buying based on how often I had to replace parts for this machine.[/COLOR]
Sorry but I do not understand the above