Some may remember that about a month ago, I got input from this forum on my failed DMD for my TZ. The concensus was that I needed to get a HV kit for the driver board. I did so and installed all 22 components and IT WORKED! I was really happy as this was my first soldering and board job! Bad news is that is only lasted for about 20 minutes. After playing a while the display just went blank again. (no garbling, fading, etc...just blank)

I think there may be a different problem now though.

Before I installed the new HV kit my voltages to the DMD were:
Pin 1 to 8 are were: 116.4, 96.6, na, 0, 0, 5, 12.2, and 0.7 (obvious pin 8 voltage issue)

Now after this new failure they are:
Pin 1 to 8 are are now: 0.4, 0.5, na, 0, 0, 4.9, 12.3, and 61.8 (pin 8 is good but 1 & 2 now bad)
(Pin 1 goes to -11.2 when I unplug the cord from the DMD)

I have tested my DMD on a known good machine and it works. I know pin 1 and 2 should be -112 and -100 when plugged in. Any suggestions for next steps since they are not?

Txs..guess I am not sure why the new parts would be suspect though since the pin 8 62v circuit is now working properly. Would the wpc hv kit also affect the 112 and 100 v circuits as well?

Well, I suddenly feel a lot less intelligent but I still have no idea what actionable steps to take to continue trouble shooting or repairing. I will keep studying though. Think i need schematics or somthing to see what components are included in these 112 and 100v circuits. I will figure it out.

Thanks everyone. I am going to study the schematic and check all of the following with the board pulled and not powered:

Continuity between components
Look for solder bridges
Diode checks
Resistor checks

Not sure if the following is a correct approach but I will also check capacitors using the diode check then look for a residual voltage. (??) Also not sure how to check transistors but assume they may be suspect if I find bad resistors.

Should I do any of the above or any other checks while powered up in the pin? (I do not yet have any independent power sources.)

Thanks again. I truly appreciate that you folks take time out to help a novice. I really enjoy working on these things but quickly get stumped when things do not work as planned. Part of the learning process I suppose.

Thank you! component check showed the following as bad:

Q4 2N5401 (diode test showed 120/10 on flanking legs)
Q10 2N5551 (diode test showed 120/670 on flanking legs)
R3 RCF1/2-47K (ohms ramped up to 43k)
R6 RCF1/2-47K (ohms slowly ramped up to 23.1k)
R12 RCF1/2-47K (ohms slowly ramped up to 42.1k)
R13 RCF1/2-47K (ohms slowly ramped up to 23.1k)

I am confused about transistors Q3 and Q7 (both MJE15030) and Q6 (MJE15031)
With proper lead on metal tab, the three legs were about 630 on one end, 0 on middle, and 1 on the other end. This seems different than the wiki expects but my new components in my extra kit act the same way. Do these need to be powered to be properly tested?

I have a spare kit so I can change these out. Worried though about why they might have failed this time. Hate to smoke my last set of spares with the same unresolved problem.

I think I may have found a solder bridge between the legs of Q5. Some little metal thread flaked off. Although Q5 seems ok I wonder if that might have messed with Q4, etc. I am going to replace Q4 and Q10 and try it unless I hear otherwise from someone between now and then.

Thanks again.

HOORAY! It is working and has been for the last hour or so.

Thanks again for all the help. Not many would understand but those that do are probably on this site. In my opinion, there are not too many things in life more satisfying than seeing that display light up after such a "labor of love".

Thanks again!