[USER=12157]@Low_Boy[/USER] -not to be a PITA
But this too can help you with the Header and backprobing it...
Get one of these...
[ATTACH=full]34979[/ATTACH]
If you own a car, you prolly' already have one, these are the OLDER style 6-24V - circuit testers. The ones that use a bulb versus LED types.
Why Bulb? Because of it's non-directional properties. It lets current flow thru both directions. LED are diodes one-way devices - so to check that header, you'll need the one that has that bulb - looks like a lantern type
Now, you'll need it for your Header check...
You'll need to power up the radio for this so you can let the HEADER power the light and show you what does work and what isn't...case ground will be fine for that alligator clip - this is not an insulated chassis radio...
Best results here are to write down your color code to position on the header - for this will help you find out where to look for the problems if you see something isn't right...
Just attach the clip to case ground and power up the radio and touch the tip of the probe to the exposed connector in the header and probe across looking to see which line in that head has power...
Switch to another mode
Repeat, checking each line on that header to see if the bulb lights...
Do this for ALL the modes...
Did you have light on more than one pin of that header?
- Two lines (or more) means you have found an issue with more lines are receiving power - each line should only work for EACH mode only ONE line.
IF lamp shows inconsistency in brightness, theres' another clue as to where you have problems with power draw.
- Dimming or unequal brightness may indicate power being taken from that line to feed others that may not be able to light the lamp but show a power draw keeping parts from (in this case - Switching Transistors) from working right and shunting signal
- or you are sending power into an adjacent line that simply has a soldering problem - meaning that it is past the Diode Matrix and is in close proximity to another circuit you're currently checking (cross feeding)
- Or power ARRIVING to the header and cross feeding into that line from another section - which can cause a transistor to stay on when it shouldn't.
Hope these hints help.
