G05 801 Horizontal Collapse

TSB

Well-known member
Joined
Jan 14, 2016
Messages
2,541
Reaction score
916
Location
Alaska
I hooked up the oscilloscope and verified the X/Y Out voltages of the board, and it all checks out.

I moved to the monitor, pulling the Deflection and Regulator pcbs. There were obvious cold solder joints on the Deflection pcb. All headers and major resistors got new solder.

F700 was blown. (I'll need to order a replacement)
Q707 & 708 are good.
Q704/5/6 all test good, but the vector faq says not to trust your dmm when checking those.
Q701/2/3 also test good
I also checked most of the diodes and resistors in that area, and found them within specs.

What's the next logical step? Should I replace Q705/6 and the pico-fuse at F700?
 
if F700 was blown, then something is shorted in the 700 section. I don't know the transistors by their locations, I only know them by what the parts are. I'll relay some of my experiences with vector monitors.

any shorted semiconductors will cause fuses to blow. on B&W vector monitors the deflection fuses are 2A fast blo.

if D608/708 is bad, then the U07/U57 pre-drive transistors even if they test good will be bad and will lead to recurring failure of the 3716/3792 transistors in the respective section. (I picked up this valuable bit of intelligence from B&W monitor FAQ). the test procedure for 3716/3792 transistors is identical to how andrewb has it in the how to bring up a 6100 guide. it's fashionable in some circles to use the higher current 5886/5884 replacement parts, I'm told to never use these on the B&W monitors, but they can be good for 6100s.

in the 600 and 700 sections are also some TO-92 transistors, TIS98s (NPN, most likely good) and a 2N3906 (PNP, can fail and cause the fuse to blow). I use one of those $15 component testers off Amazon and it makes life significantly easier working with vector monitors lol

be certain also that the solder to the board in the HV cage is all redone and the same for all the header pins on the deflection board. I have several vector games to keep alive at work and the V2000 in Omega Race was the biggest nuisance until I picked up on the diodes messing up the pre-drive transistors. the aforementioned guides if you've not read them fully will be beneficial in the long-term.
 
I just finished going through every diode and resistor in the 700 side. They all checked out.

I pulled all the transistors, and they tested fine (again, the faq says not to trust the dmm here).

ZD700/701 work, but maybe aren't while under load?

At this point, I should replace Q705/6 and F700.
Could anything else be bad?
 
did you check the frame transistor sockets that you have no wires broken off? or the plugs that go in the deflection board, since I think those are IDC, that they're all intact?

Asteroids at work wasn't collapsing, it was like losing half the screen, the fix was replacing the Y axis 3716/3792s. I'm uncertain if it had 5886/5884s previously, cause the man is kind of a mark and listens to certain community figures like their words are gospel. you don't want to use those on B&W vector monitors.
 
With 801's, always start by checking the power supply. Power just the PS, with the output connector unplugged (just the 6-pin plug connected) and verify all voltages on the output pins (+25 and -25).

Beyond that, mecha's advice is correct. Also, look for cracked traces, not just reflowing the headers. You can get trace breaks that a reflow won't fix. So always tone out all paths, from the tips of the pins on the parts side, to test points or other spots on the PCB, that include as much of the trace as possible.

Also, the pico fuses should be testable in-circuit. If they aren't blown open, they are fine. (Note that some 801's don't have the pico fuses, but rather have regular glass fuses in separate fuse holders, on the yoke wires. On those monitors, the pico fuse locations just have jumper wires soldered in.)
 
did you check the frame transistor sockets that you have no wires broken off? or the plugs that go in the deflection board, since I think those are IDC, that they're all intact?

Asteroids at work wasn't collapsing, it was like losing half the screen, the fix was replacing the Y axis 3716/3792s. I'm uncertain if it had 5886/5884s previously, cause the man is kind of a mark and listens to certain community figures like their words are gospel. you don't want to use those on B&W vector monitors.
I checked the sockets, all the way around, just to make sure that none of them were burnt, and that they were making good connection.


Well, I didn't have a pico fuse on-hand, so I stole the one from Y to test X after replacing Q705 & Q706.
X deflection is working with the replacement Q705/6, but I need to order a new pico fuse.

The old still test good out of circuit, so they must be failing under load.
 
Last edited:
With 801's, always start by checking the power supply. Power just the PS, with the output connector unplugged (just the 6-pin plug connected) and verify all voltages on the output pins (+25 and -25).

Beyond that, mecha's advice is correct. Also, look for cracked traces, not just reflowing the headers. You can get trace breaks that a reflow won't fix. So always tone out all paths, from the tips of the pins on the parts side, to test points or other spots on the PCB, that include as much of the trace as possible.

Also, the pico fuses should be testable in-circuit. If they aren't blown open, they are fine. (Note that some 801's don't have the pico fuses, but rather have regular glass fuses in separate fuse holders, on the yoke wires. On those monitors, the pico fuse locations just have jumper wires soldered in.)

I think I'll order a few of these fuses: https://www.digikey.com/short/5pn47jpj

Looking to restock my U07 & U57 since I'm ordering fuses from DigiKey, but they are NLA.
Is there a good current-production sub for these?
 
You can also install in-line plastic fuse holder on the yoke wires, and ditch the picofuses (just jumper them). That's what they did at the factory on later models, as you'll see later 801 deflection boards with the picofuses replaced by jumpers. If your yoke already has the inline fuse holders, you don't even need the picofuses.

APAR has CEN-07/57 replacements. I used to use ZTX-658 and 758 (which you had to install backwards, and they needed their own heatsinks, but they worked fine), however those are also OOS on Digikey.
 
You can also install in-line plastic fuse holder on the yoke wires, and ditch the picofuses (just jumper them). That's what they did at the factory on later models, as you'll see later 801 deflection boards with the picofuses replaced by jumpers. If your yoke already has the inline fuse holders, you don't even need the picofuses.

APAR has CEN-07/57 replacements. I used to use ZTX-658 and 758 (which you had to install backwards, and they needed their own heatsinks, but they worked fine), however those are also OOS on Digikey.
oh dang. I just ordered ztx653 and 753… are they good subs?
 
oh dang. I just ordered ztx653 and 753… are they good subs?

They're fine if you can find them. I've been using them for years on all vector deflection boards, b/w and color.

Just know that you also need to order the heatsinks that go with them. And you'll need to drill small holes in the sinks, to screw them to the board.

And the most important thing is that they need to be installed in the opposite direction to the original parts. (So the rounded side of the package faces the opposite way from the beveled side of the originals.)
 
  • Like
Reactions: TSB
Back
Top Bottom