Dead Foot Pedal Troubleshooting & How To Get Access to Circuit Board?

[dude99]

Hi-

I have a Kimball Swinger 800 Series that I'm trying to repair a dead "D" foot pedal for. Looking at the schematics it appears that the problem areas may be in these diodes (the area circled in blue). And a closer pic. My main questions are:

1. If I'm measuring accurately, the voltage for the diodes that correspond with the "D" pedal measure 0.1 volts and all of the other working pedals measure between 0.7 and 0.9 volts. Does this sound accurate? What does that information tell me exactly?

2. The back of the circuit board is very hard to access. I can't seem to remove the white plastic pins from the chassis to remove the circuit board and get a better look at it/ be able to repair. What's the best way to go about that?

3. The service manual suggests to check for faulty sustain capacitors. How do I find where those are located exactly?

Thanks.

[tucsondave]

The below is assuming you have D tone generator signal to the pedal keyer board.

You can check C3 for short by measuring resistance between the anode of D30 and pin 11 marked "factory test point" on the schematic.
If not shorted then....

1. The information in #1 tells us nothing since you don't say how you were measuring them.
Start by using ground for your voltage measurement reference.
A. Compare pedal key switch input at terminal 3 (D pedal) to terminal 4 (D# pedal).
B. Compare anode voltage of D30 (D pedal) to anode of D31 (D# pedal).
C. Compare junction of R24 & R3 D pedal pressed, to junction of R23 & R4 D# pedal pressed.

2. You don't remove the plastic stand-offs from the chassis. You pinch the latch at the surface of the circuit board to release the board from the stand-off.

3. The sustain capacitors are the 13 black vertically mounted capacitors grouped together.

td

[dude99]

Thanks. I'm having trouble locating pin 11 on the board. I see it on the schematic but not on the board itself. Can you help me with that from this pic?: http://imgur.com/ItqCQff

[tucsondave]

According to the legend pin 11 in a square box means it's a terminal on the right end of the board. Access is via nail #11 on the connector circuit board. Based on the position of R71 going to terminal 10 it looks like the connector in your photo with the yellow label is where #11 is located.

td