Quoted from Sea_Wolf:Just tested the U2 pin 5 for voltage and got 0.00. All the rest of the pins on U2 registered something, although I barely got any reading on pin 3.
You don't by any chance have a logic probe to confirm?
The voltage on pin 3 should be similar to pins 2, 21 and 22.
Quoted from Sea_Wolf:Just tested the C-6 cap on the SDB on low resistance ohms and it measured 0.52 which was about the same as C-3,C-4,C-5 and C-6. They were all between 0.52 and 0.55.
Your measurements don't look right. Maybe the meter wasn't set to ohms properly.
If your meter is auto-ranging, set it to the "Ω" mode which measures resistance.
If it's not auto-ranging, set it to the "2000" "Ω" mode which measures resistance up to 2000 ohms.
I'm getting about 820 ohms across those capacitors (red meter lead on one capacitor leg, black meter lead on the other capacitor leg).
Quoted from Sea_Wolf:I went ahead and ordered a small Tune up kit for the LDB and SDB from eBay so that I will have, resistors, capacitors, SCRs etc.... in case I need them later. I’m guessing that’s where we’re headed? What’s your opinion?
Yes, as it stands you likely have one (possibly two) faulty 2N5060 SCRs and 4514 logic chip for the lamp board. How are your soldering skills?
On the SDB, you likely have a faulty TIP102 driver transistor at Q9, burnt 330 ohm resistor at R26, possibly damaged 1N4004 diode at CR9. I would also replace the diode across the lower pop bumper coil (presuming the coil isn't cooked). NOTE, diodes are directional and must be installed in the correct orientation. One side of the diode body has a band indicating it's the cathode leg.
Hopefully the transistor array at U3 is ok, but give it a quick measurement to check:
With the machine on and in game over mode, measure the voltages at pins 2 and 3 of U3 on the SDB. Compare against the voltages of pins 2 and 3 of U1 and U4.
Quoted from Sea_Wolf:Wonder if not having the little diode on the lower pop bumper switch caused the transistor or resistor on the SDB to fail.
No, those green capacitors often short causing pop bumper and other switch issues. Operators usually cut them out once faulty, but it leaves the side effect that the pop bumper switch will not be as responsive and miss scoring sometimes.