Author Topic: Need help with Orion 13in Arcade Monitor Repair (Read 4765 times)

floobydust · « **Reply #25 on:** February 06, 2020, 05:33:44 am »

From the KT-1403V schematic, I can't really see anything shorting that would cause those parts to burn up like that. It's weird R502 10k 1/2W is in series with 180k or 100k 1/4W so where did the overload come from? Q501, C503 see only 12V.

I found a factory parts list for KT-1403V pg. 60

fzabkar · « **Reply #26 on:** February 06, 2020, 05:51:07 am »

Quote from: floobydust on February 06, 2020, 05:33:44 am

From the KT-1403V schematic, I can't really see anything shorting that would cause those parts to burn up like that. It's weird R502 10k 1/2W is in series with 180k or 100k 1/4W so where did the overload come from? Q501, C503 see only 12V.

I was thinking the same thing. :-?

floobydust · « **Reply #27 on:** February 06, 2020, 06:03:58 am »

It looks like an automatic brightness limiter/sub-contrast section, and the only time I have seen stuff like that burn up was the flyback transformer return winding pin 6 going open-circuit and the HV return then ended up being the next leg pin 8. I can't see the x-ray protection open-circuiting R404, D401 etc. allowing pin 6 up to high voltage, either of which would cook R502.
I would check ohmeter readings on T402 pins 6-7, 7-8, 6-GND to see if there is continuity or what readings there are.

trad1984 · « **Reply #28 on:** February 06, 2020, 06:39:32 am »

Ok, thanks floobydust! I will check those pins when i get home and I will post the results of what I find. I am assuming for ground I can just use the metal portion of the chassis? For what it is worth I do think that G501 is bad (based off of the transistor testing procedure I found on YouTube).

Moshly · « **Reply #29 on:** February 06, 2020, 07:13:12 am »

If you end up needing a replacement flyback or a whole replacement chassis you could try contacting TNT Amusements.

https://www.youtube.com/channel/UCyjs8rzlagt8XfWxdPQnVRw

shakalnokturn · « **Reply #30 on:** February 06, 2020, 04:11:59 pm »

I have to agree with floobydust, considering the high values of roast resistors and their positions this is starting to like a defective FBT.
I would check D401, C425 before coming to that conclusion though.

trad1984 · « **Reply #31 on:** February 06, 2020, 09:31:07 pm »

So I checked the pins as suggested and I get good continuity between 6 and 7 and from 6 to ground, but not 7 to 8. Also, I checked d401 and it is good, but I am having trouble checking c425. C425 shows continuity, but I can see the charge and discharge on my multimeter for some reason.

james_s · « **Reply #32 on:** February 07, 2020, 01:00:00 am »

Is that out of circuit? If so it sounds leaky. A capacitor should show a resistance that gradually decreases to open circuit if you test it with the Ohms range on a multimeter. If it plateaus and never goes infinite then that's leakage.

shakalnokturn · « **Reply #33 on:** February 07, 2020, 02:43:07 am »

Quote from: trad1984 on February 06, 2020, 09:31:07 pm

So I checked the pins as suggested and I get good continuity between 6 and 7 and from 6 to ground, but not 7 to 8. Also, I checked d401 and it is good, but I am having trouble checking c425. C425 shows continuity, but I can see the charge and discharge on my multimeter for some reason.

Open between 7 and 8, so floobydust was right.
Don't bother with C425.
In some cases you can scratch away at the potting around the FBT pins and find the open winding just before the wire is soldered to the pin. More likely you'll waste your time though...

trad1984 · « **Reply #34 on:** February 07, 2020, 03:09:54 am »

Ok, so just to confirm, the Flyback Transformer is bad right? I've looked online for a replacement and it appears there are some out there, but most are shipping from somewhere overseas and are pretty expensive. I may just break down and do an LCD conversion or see if I can get a completely new chassis.

shakalnokturn · « **Reply #35 on:** February 07, 2020, 08:52:06 pm »

Yes, if there is no measurable resistance between pins 7 and 8 the transformer is defective.

james_s · « **Reply #36 on:** February 08, 2020, 03:15:38 am »

Just make sure you are counting the pins correctly, sometimes there is a spot for a pin with no actual pin there that still gets counted. If you are positive that it's defective then I would cut in there and try to fix it, nothing to lose at that point. You should also try all the usual arcade parts sources and see if you can find a replacement. CRTs are no longer made and they're getting harder to find so it's increasingly worth spending the effort to repair monitors I would have written off a few years ago.

trad1984 · « **Reply #37 on:** February 08, 2020, 05:16:27 am »

I will verify again tonight that I have the right pins, as for the cutting into the flyback, I wouldn't know where to start.

shakalnokturn · « **Reply #38 on:** February 09, 2020, 12:05:37 am »

Quote from: trad1984 on February 08, 2020, 05:16:27 am

I will verify again tonight that I have the right pins, as for the cutting into the flyback, I wouldn't know where to start.

Scratching delicately around pin 7 or 8 is a good place to start.

trad1984 · « **Reply #39 on:** February 09, 2020, 06:01:54 pm »

Are you talking about just the soldering on the green side or actually removing the flyback transformer and cleaning the pins.

floobydust · « **Reply #40 on:** February 09, 2020, 06:58:40 pm »

I found confusion about the flyback's actual winding configuration. OP should double check what he's finding. Just tell us the ohmmeter readings between pins 5 thru 8.
Kortek KV-1403V flyback KFS-61202 or KFS-61202a crosses to H.R. Diemen HR 46100 but the winding schematic is different, showing taps instead of separate windings and possibly mixing up pin 8 with pin 6? HR 46100 used for KFS61202A/KT2003V DUGO, KORTEC VS20475T, TATUNG 19"/20"TELCO VGA.
KT-1403NA also used the same flyback, that circuit includes that pin 5 is GND, and primary 1,2,3,4 daisy-chained and secondary 6,8,7 is also daisy-chained.
So the KT-1403V schematic is a bit misleading for the flyback windings.

I would double check you're using the right pinout, and the one winding 7-8 is truly open-circuit. There must be continuity between 6-8, 8-7 I think.
To remove the transformer from the board. You'd need a good solder sucker or lots of solder wick. I don't think flyback transformer open-circuits are accessible, to do surgery.
They are potted and the only place to fix a bad connection is at the underbelly at the pins, and that is too much for me.

KT-1403V repair info symptoms has some faults he found.

james_s · « **Reply #41 on:** February 09, 2020, 07:25:36 pm »

Also for what it's worth, in ~20 years of repairing CRT monitors of various types I have *never* seen an open circuit winding in a flyback. I'm sure it happens occasionally but it's not something I've ever seen. Normally the failures I see are shorted turns, occasionally faulty diodes in the HV secondary, faults in the focus/screen pot assembly and arcing due to cracks in the casing.

floobydust · « **Reply #42 on:** February 09, 2020, 07:38:22 pm »

Somehow pin 8 went up to high voltage. This is my theory for OP's burned up parts.
I would think the flyback was arcing inside and that can eventually cause an open-circuit after the fine wire copper melts. But ohmmeter readings would be high due to carbon tracking. OP did not mention the values he is measuring. I've never seen a flyback that could be repaired, as much as I dreamed I could fix them.

trad1984 · « **Reply #43 on:** February 09, 2020, 09:15:30 pm »

All, thank you very much for all the replies, you guys are awesome. I would love to provide the readings, but I'm not sure I know how to do more than check the continuity. Are you suggesting I apply power to theboard and take the voltage readings at the pins?

floobydust · « **Reply #44 on:** February 09, 2020, 09:39:03 pm »

No, just take some ohmmeter readings at the flyback and write them down and post the measurements here. Just to double check. I don't have any of your numbers. It's normal to get over 200 ohms for some HV windings, in case you are only using the continuity-function on your multimeter.
Open-circuit (megohms) between 8-7 does confirm the flyback is toast. Something like between pin 6-8, 8-7, pin 8-5, pin 7-5, 9-7, kind of thing. I would look at the flyback outside to see if any signs of melting on the case too. Sometimes an arc will melt a small spot as a giveaway that the transformer has failed.

trad1984 · « **Reply #45 on:** February 10, 2020, 12:08:18 am »

So I tried to measure the resistance between the pens, but I cant seem to get any other value except 0 regardless of the ohm setting I use. The only place I dont get 0 is where the display doesn't change at all (no continuity) and this happens with any combination that includes pin 8.

floobydust · « **Reply #46 on:** February 10, 2020, 01:27:22 am »

Pin 8 winding must connect to either pin 7 and pin 6, so the flyback is bad. I haven't seen a replacement but it goes under a few different part numbers/makes. You could call/email Arcadeshop and see if they have one or any ideas.
I would look at fitting an LCD monitor from an old laptop or get a monitor that fits. You take a laptop LCD panel (with known part number) and connect to matching "HDMI+DVI+VGA+Audio LCD Driver Monitor Converter Lvds Board" from eBay.

james_s · « **Reply #47 on:** February 10, 2020, 01:44:34 am »

0 means zero ohms, IE no resistance, or rather resistance below what the meter is capable of measuring. This is normal for high frequency transformers, many of the windings are only a few turns. Open circuit is whatever it displays with the probes not connected to anything, on most meters it's something like O.L.

trad1984 · « **Reply #48 on:** February 10, 2020, 02:09:09 am »

Ok, that makes sense. I tried a second meter and was getting around .7 ohms on all the ones that had continuity. I try the arcade shop and see if they have a replacement.


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Author Topic: Need help with Orion 13in Arcade Monitor Repair (Read 4765 times)

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