g05-802 spot killer on but have picture

jacklick

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First, I know the issue is on the deflection board because I swap in a known good and game works as it should. If I remove d504, spot killer LED, the game behaves normally with brightness and contrast control, however with d504 installed I have to turn brightness up and get spider effect, turn down and image goes away.

Deflection board has been recapped (at least c500-503 have)


from B&W vector Faq 1.2
Symptom: Monitor Powers Up, Spot Killer On. If The Brightness Is Turned Up, A Complete
Screen Is Seen, But It Looks Like A Spider Web.
Check and replace as necessary the brightness or the contrast pot. Also check for bad solder joint,
or a bad tantalum capacitor in the spot killer circuit.


^^ not sure what tantalum is part of spot killer don't see it on schematic but this is the symptom.

should I start with q500- 502?
 
Replace Q500 to start, especially if the R100/101 mod hasn't been done. (Realistically you should replace all of the small transistors, as they cheap, and often cooked to some degree.)

This should be standard procedure on these, as it's a relatively common problem. See this thread, and the one it links to:

https://forums.arcade-museum.com/showthread.php?t=403217
 
Replace Q500 to start, especially if the R100/101 mod hasn't been done. (Realistically you should replace all of the small transistors, as they cheap, and often cooked to some degree.)

This should be standard procedure on these, as it's a relatively common problem. See this thread, and the one it links to:

https://forums.arcade-museum.com/showthread.php?t=403217

yea this is an issue 5 deflection board so r100/101 are jumpered with w8 & w10 ( i think).

I will start testing the spot killer parts tomorrow I guess. I may shot gun if I have them on hand.
 
Ok bizarre but in order.
Pulled q500, q501, q502 and they all tested fine using diode test method.
pulled one leg and tested r500-r510 all tested fine.
Didn't test the 1n914 diodes.

swapped q500, q501, q502 from working deflection board and spot killer issue follows the transistors. Not sure which one is bad but looks like at least the problem is one of them. guess I have to order some.

from andrewb https://forums.arcade-museum.com/showpost.php?p=3482741&postcount=5

Q500, Q501 are TPS98, which can be replaced with MPSA06 (easy to get).

Q502 is 2N3906, which is easy to get.
 
Nice find. Congrats.

When you tested the transistors, you did the diode test, but did you check for a short between the two outer pins? (collector to emitter, and vice-versa) Sometimes people forget this, and you can get ones that look ok for the two outer pins to the center pin (base), but will be shorted between the two outer pins. (In general, you can see all sorts of weirdness when testing transistors and diodes, so it's not surprising.)

Also, all of those transistors are super common. If you have any junk PCBs around with the small black transistors on them, there's a good chance they might have MPSA06's and/or 3906's.
 
Nice find. Congrats.

When you tested the transistors, you did the diode test, but did you check for a short between the two outer pins? (collector to emitter, and vice-versa) Sometimes people forget this, and you can get ones that look ok for the two outer pins to the center pin (base), but will be shorted between the two outer pins. (In general, you can see all sorts of weirdness when testing transistors and diodes, so it's not surprising.)

Also, all of those transistors are super common. If you have any junk PCBs around with the small black transistors on them, there's a good chance they might have MPSA06's and/or 3906's.

Yep tested each leg to each other leg. Will redo it as I replace them just to make sure.

good hint on junk pcb...maybe I can find one but went ahead and ordered some mpsa06 and the b+ filter caps.

Update> I had some new 2n3906 on hand and replace q502 but spotkiller is on. So either q500 or q501. Geez i hope I am not confusing stuff with all the swapping :)
 
got some new mspa06 in yesterday. replaced q500 and q501 and the spot killer issue is resolved. Tested both transistors out of ckt using diode test and they test fine. I guess the failure condition only happens when under load or something. Also replaced p500 header, ooked a bit worse for wear, and repinned new connector. Looked a bit worse for wear.

Now this deflection board has developed a new problem with partial horizontal collapse. Will keep this thread on topic and save that one for later.

video start of showing the spot killer issue.
https://youtu.be/43Vqg_Uxths?t=5m14s

video start of spot killer issue resolved but some partial horz collapse
https://youtu.be/43Vqg_Uxths?t=21m18s
 
got some new mspa06 in yesterday. replaced q500 and q501 and the spot killer issue is resolved. Tested both transistors out of ckt using diode test and they test fine. I guess the failure condition only happens when under load or something. Also replaced p500 header, ooked a bit worse for wear, and repinned new connector. Looked a bit worse for wear.

Now this deflection board has developed a new problem with partial horizontal collapse. Will keep this thread on topic and save that one for later.

video start of showing the spot killer issue.
https://youtu.be/43Vqg_Uxths?t=5m14s

video start of spot killer issue resolved but some partial horz collapse
https://youtu.be/43Vqg_Uxths?t=21m18s


Sanity check (and sorry if you already mentioned this, I didn't watch the whole video, just 5 mins, till it showed the collapse): Are you sure the partial horiz collapse is not due to the game board? (Can you verify the game board with a scope, or other good deflection board?)

Also, did you recap that deflection board? If so, where did you get the caps from?

You should also test the B+ off of the rectifier on the deflection board. You should have +34 and -34 volts or so (give or take a couple of volts). Also, test your frame transistors again.
 
Sanity check (and sorry if you already mentioned this, I didn't watch the whole video, just 5 mins, till it showed the collapse): Are you sure the partial horiz collapse is not due to the game board? (Can you verify the game board with a scope, or other good deflection board?)

Also, did you recap that deflection board? If so, where did you get the caps from?

You should also test the B+ off of the rectifier on the deflection board. You should have +34 and -34 volts or so (give or take a couple of volts). Also, test your frame transistors again.

Video that painful huh :)

Yea, later in the video I put the other deflection board in and there is no partial horz collapse so that eliminates the frame transistors, PCB and HV.

I did recap. at least c500-c503, that leaves only one cap, which tested fine with ESR...not sure where the caps were from though..just had them in my box. I have the rest of a Ian Kellogg cap kit that I can redo it though. The weird thing is partial horizontal collapse issue wasn't there before...had some image shaking but now that appears gone and this pops up. Maybe coincidence or it was foretelling a failure.

I will replace caps (why not) check B+ and revert.
 
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