ICB - resistors for capacitors?

Bullwinkle

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Trying to diagnose the lights for the holes (currently not working). Looking at the manual, c1-c69 should be a 470pf 50v cap. Instead, there seems to be a row of resistors. The last zeke's peak board I worked in did have caps there. It looks to be factory installed. What gives? Is this a suitable replacement?

IMG_1326.jpg
 
There are some TIP120/125 transistors on the pcb. Use the schematics to find out which ones are in the circuit for the lights that are not working. These are usually the culprit for dead lights. Of course check your bulb and lamp holder first. You might also check the edge connector because the pins they used were pretty crappy on these.
 
Yeah, I did have a wire come loose on the j2 edge connector position 2.. Fixed that... Will look at the transistors next. All the lights are out and they all went at the same time. My guess is the loose wire grounded/shorted something and blew the transistor Thanks for the tip (pun intended) ;)
 
If all of them are out I would start looking at the power supply first. Also look down in the edge connectors for pins that are flattened out. They used brass pins and they tend to loose their tension and/or crack.
I had alot of problems on mine that would come and go until I replaced all three edge connectors.
 
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OK, I know I've tested TIP120 transistors on a Williams system 6 driver board. Essentially using my DMM in diode mode, the black lead to the metal tab (or center leg) and the red lead to either side and get the .4 to .6 volts, which I do. I'm not sure what I need to do for a TIP 125. Is there a similar way to test these and what voltages am I looking for?

Thanks
 
120 is a NPN and 125 is PNP so test it the same as the 120 but reverse the leads. Meter on diode test, power off on cab. You should read around .5v one way and open if you flip the leads around. Most datasheets will have a schematic of the part which will show you the diodes and give you a better idea how to test it.
 
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