Troubleshooting Guide

If your PPM3 does not work at all, recheck the following:

•correct orientation of VR1 and the ICs (see PC board layout diagram).

•You should be able to measure the voltage on the input and output terminals of voltage regulator VR1. The input should be whatever the supply voltage is specified at, while the output should be 5 VDC +/- 5%.

•correct polarity of all electrolytic capacitors.

•correct orientation of diodes

•all solder connections

STILL HAVING TROUBLE?

While we had hoped that it wouldn’t come to this, if you are still having trouble with your Phone Patch Mixer, here are a few additional suggestions.

Use a methodical, logical troubleshooting technique. Most problems can be solved using common sense. A volt-ohm meter and a clear head are usually all that are needed to correct any problem. Most problems are due to misplaced parts and/or bad solder connections. Working backwards through the assembly steps will often lead you to the problem. Revisit the extensive theory of operation included in this manual and try to apply it to your specific problem.

Have another set of eyes look through your work. Here at the shop we have often run into a “stone wall” of a problem only to have a fellow technician see our obvious error. It is sometimes very difficult to see your own mistake; taking a break can often solve this common problem.

Make sure that you have “checked” all the assembly steps boxes; you may have forgotten one or two of them.

PROBLEM: I get no audio when doing the initial test of the audio section.

SOLUTION: Check the volume level on your source to be sure it’s up loud enough for you to hear. Next check your stereo or other device to be sure it’s on, that it’s set for the input you’ve connected to it (AUX or other . . . whatever an external source is on your particular stereo) and make sure the volume is loud enough. Another thing to check is that the volume pot, R2, is turned up enough for you to hear the output from the PPM3. You should always use

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