Hope this jumps you to the right section "Single Horizontal Line"
https://www.repairfaq.org/REPAIR/F_monfaq7.html#MONFAQ_002

BitWrangler wrote on 2021-12-05, 19:56:

Hope this jumps you to the right section "Single Horizontal Line"
https://www.repairfaq.org/REPAIR/F_monfaq7.html#MONFAQ_002

Amazing, thank you.

BitWrangler wrote on 2021-12-05, 19:56:

Hope this jumps you to the right section "Single Horizontal Line"
https://www.repairfaq.org/REPAIR/F_monfaq7.html#MONFAQ_002

One typical fault I already encountered in audio amplifiers and CRT oscilloscopes I do not see explicitly mentioned in the Repair FAQ (great document collection, BTW!) is "shorted bypass cap". If the bypass cap is part of an RC filter for the supply voltage, a shorted cap doesn't necessarily cause any damage, because the R before the cap limits the short circuit current. The shorted bypass cap still causes loss of the supply voltage for a part of the circuit. So don't just check caps with an impedance (ESR) meter and be happy about extremely low value, but als check them with a DC continuity tester for actual shorts.

Vertical IC dies usually when retrace kick capacitor dry up. This capacitor is next to vertical IC. Also there will be vertical power supply has a fusible resistor somewhere else open also. Confirm that they were defective and replace them.

Cheers,

pentiumspeed wrote on 2021-12-05, 22:02:

Vertical IC dies usually when retrace kick capacitor dry up. This capacitor is next to vertical IC. Also there will be vertical power supply has a fusible resistor somewhere else open also. Confirm that they were defective and replace them.

Cheers,

Thank you

pentiumspeed wrote on 2021-12-05, 22:02:

Vertical IC dies usually when retrace kick capacitor dry up. This capacitor is next to vertical IC. Also there will be vertical power supply has a fusible resistor somewhere else open also. Confirm that they were defective and replace them.

Cheers,

So according the schematic I believe this is the Vertical IC. I'm fine at swapping out parts, but troubleshooting these things is a different story. Arcade monitors I usually just have to do a cap kit, or replace a flyback from time to time. I'm afraid I may be getting in over my head with this but figured with the right help maybe I can get it working 😀.

Am I in the right place? IC 402? Attached to the big black heatsink?

Thanks again.

Anybody have the Nec 3ds service manual?

Unknown_K wrote on 2021-12-06, 05:41:

Anybody have the Nec 3ds service manual?

I have it
https://www.dropbox.com/s/yvttkzr78cohwon/nec … jc1404.pdf?dl=0

Check the part number on this IC and you will get a data sheet on this IC so you can know which capacitors are for the vertical IC and replace them all and find the fusible resistor and replace this as well. The vertical IC supply will be shown in the data sheet and follow this back to the fusible resistor. Also check diodes.

Cheers,

ArcadEd wrote on 2021-12-06, 05:47:

Unknown_K wrote on 2021-12-06, 05:41:

Anybody have the Nec 3ds service manual?

I have it
https://www.dropbox.com/s/yvttkzr78cohwon/nec … jc1404.pdf?dl=0

Thanks

I got the data sheet for the IC, but I wanted to ask about some of the resistors. I tried to take a close up picture, is it normal for them to have like that black leakage? Some have green corrosion as well.

That black thing with white band is diode, rarely fail, but check it with your meter to confirm is good. What is the two capacitors values are? These capacitors' juice is what cause corrosion and got dried up, which blown that vertical IC. When this happens, one more thing will be also blown is fusible resistor somewhere else that supply the vertical IC's supply.

You're forgetting my comments. They will be true. I have done these vertical IC failures repair all the time back in the day when CRT ruled the era. Real reason is the capacitor kick, well kicks the beam that is ending at bottom of scanning field up to top to begin new field, got dried up and killed the vertical IC and in turn blown the "fuse" fusible resistor, always.

ALWAYS confirm by checking various items items IS defective or good as I had, I outlined and replace only the defective. Do not just assume they are bad and replace without knowing except the capacitors. Refer to the vertical IC schematic example and replace these capacitors as you cannot check unless you have a ESR meter on hand. Which is not what multimeter's have in their features.

Cheers,

pentiumspeed wrote on 2021-12-19, 23:00:

That black thing with white band is diode, rarely fail, but check it with your meter to confirm is good. What is the two capac […]
Show full quote

That black thing with white band is diode, rarely fail, but check it with your meter to confirm is good. What is the two capacitors values are? These capacitors' juice is what cause corrosion and got dried up, which blown that vertical IC. When this happens, one more thing will be also blown is fusible resistor somewhere else that supply the vertical IC's supply.

You're forgetting my comments. They will be true. I have done these vertical IC failures repair all the time back in the day when CRT ruled the era. Real reason is the capacitor kick, well kicks the beam that is ending at bottom of scanning field up to top to begin new field, got dried up and killed the vertical IC and in turn blown the "fuse" fusible resistor, always.

ALWAYS confirm by checking various items items IS defective or good as I had, I outlined and replace only the defective. Do not just assume they are bad and replace without knowing except the capacitors. Refer to the vertical IC schematic example and replace these capacitors as you cannot check unless you have a ESR meter on hand. Which is not what multimeter's have in their features.

Cheers,

I believe your comments. Just trying to narrow things down before I go into unknown territory for me like reading data sheets and schematics 😀. Physical inspection of the resistors and such 😀.
Do you mean what are the value of those caps as written on them? Obviously, like you mentioned, I can't test them correct?

35v 100uf.

Thank you.

Not need to, if you don't have ESR meter.

Yes, you do need to read the vertical IC marking and get data sheet via google for the vertical IC and this will provide you with enough information where to trace like vertical IC supply back to the source of supply and in that supply circuit there should be a fusible resistor in series, that might be open, which diode is used and capacitors for this.

If you know which capacitors for the vertical IC from the data sheet, simply replace them and vertical IC replaced but need to check that you have intact supply too.

Cheers,

Ok, that makes sense. Thank you.

I did like you suggested and found the fused resistor and it seems good. However, I found 2 blown resistors and diodes along the way. Plus a few caps that seem to have leaked.

Do you suggest replacing the LA7835 Vertical IC as well? Is there a pretty good chance it's fried?

My wording meant required! Replace IC please and that both capacitors. 100uF 35V will be also bad.

And clean off these gunk too.

Cheers,

pentiumspeed wrote on 2021-12-21, 00:11:

My wording meant required! Replace IC please and that both capacitors. 100uF 35V will be also bad.

And clean off these gunk too.

Cheers,

OK, so I found a total of 3 bad resistors and 2 bad diodes. Along with 4 caps that showed signs of leaking..
I replaced and cleaned up everything, including the IC. I checked the schematics and followed tracing from the IC to look for any more problem areas. I even scanned over the board several times. Doesn't mean I didn't miss anything.

Got it all back together fired it up. I'm getting something now, but not there yet. First picture is what it looks like as soon as I turned it on (Hooked to a computer).
Second picture is after I adjusted the H.Hold some.

Colors are off (no Brown, Yellow on my laptop screen). You can faintly make out the icons in the second picture. I labeled all wires so I know where they came off (this is a way more complicated monitor than you typical Arcade monitor, sheesh).

Progress! 😀

This looks like horizontal sync signal not making through properly or clean enough. Keep checking these components that was wet from the capacitor juice.

Cheers,