Author Topic: Need help with Orion 13in Arcade Monitor Repair (Read 5369 times)

trad1984 · « **on:** February 04, 2020, 03:32:06 am »

Hello,

I am trying to fix a 13in Orion CRT arcade monitor that stopped working. I removed the monitor from the cabinet and located a few burned up resistors and a transistor that I think is bad. I tried to look online, but couldn't find a schematic anywhere. I am having trouble identifying the burned resistors. Any help with identification or troubleshooting the board is appreciated. I attached a picture of the three burnt resistors I am trying to identify along with a picture of the area on the board where I removed them from. The two smaller resistors were side by side in the R503 and R504 spots on the board. The other larger resistor (10 k ohm?) was at the R502 spot. I checked all of the diodes and capacitors in the area and didn't find any problems, but the transistor I circled seemed to be bad.

james_s · « **Reply #1 on:** February 04, 2020, 05:50:04 am »

The one resistor that is darkened is probably still reasonably close to the correct value so you can measure it. The really toasty ones are gonna be hard to identify without a schematic. Your options are pretty much either find someone with the same model monitor or one that's similar enough to have the same parts there, or reverse engineer enough of the circuit to figure out what those parts do and take a guess at reasonable values.

trad1984 · « **Reply #2 on:** February 04, 2020, 05:57:07 am »

That is what i was afraid of, unfortunately it is pretty rare. I think I figured out the larger one (1M Ohm). Any thoughts on what might have caused them to burn up in the first place?

james_s · « **Reply #3 on:** February 04, 2020, 06:11:39 am »

Usually burned up resistors are caused by shorted semiconductors, look carefully for shorted transistors and diodes.

fzabkar · « **Reply #4 on:** February 04, 2020, 06:17:55 am »

Could we see a photo of the whole chassis?

Where does the 7-pin connector go?

Can you identify any part numbers on the flyback transformer? The FBT can often identify the chassis. ISTR that Daewoo TVs sometimes used an Orion chassis, or vice versa.

trad1984 · « **Reply #5 on:** February 04, 2020, 06:19:45 am »

I did check all the diodes in the vicinity and they all checked to only allow flow in one direction. I'm not an expert, but i think the transistor that i circled in the photo is bad based off of the testing methods I found on YouTube. I will probably give replacing that a shot. I don't have a full chassis photo on me right now, but I will take one when I get back home tonight and post it.

I will check on the fly-back transformer part numbers and the destination of the 7-pin tonight also.

trad1984 · « **Reply #6 on:** February 04, 2020, 10:45:43 pm »

I posted some additional photos below. To answer the questions from yesterday,

1. I couldn't identify any info on the flyback transformer but I did take a picture of the monitor and neck board.
2. I added a picture of the entire board as requested.
3. The 7-pin connector goes to the monitor adjustment board (see picture).

Thanks for all the info, you guys are awesome.

floobydust · « **Reply #7 on:** February 05, 2020, 12:08:15 am »

CRT monitors have a model number, chassis number, CRT number, serial number, manufacturer's name.
You'd have to find the chassis number for any luck in finding the schematic. That would be somewhere on the main board as a sticker or pcb silkscreen, check both sides. I can't see much from the fuzzy pics.
Or search for the game's name i.e. Zaxxon to find the monitor's schematic in that service manual.
Orion CRT sticker is M34JZT20X is I think 34cm CRT, not the monitor's model number.
The 500 reference designators are likely the horizontal output section.

You'll have to stare at the board and look for the root chassis number.

trad1984 · « **Reply #8 on:** February 05, 2020, 12:40:19 am »

Ok thanks, I'll take another look when I get back home. Any clue what the format would be? The only markings I could find on the chassis is a serial number that is on the side of the silver shield around the flyback transformer. It is shown in one of the pictures I posted and I believe it is 98074607.

trad1984 · « **Reply #9 on:** February 05, 2020, 02:08:56 am »

Upon further investigation here are the numbers i found:

On the CRT:
37452091
M34JZT20X
98074607

On the chassis (near the flyback transformer):
VGA 37211460

On the chassis (near the power input):
KTV-2532
97013712

I will see if I can find anything else. I also did a search for the crt model number and found a citrx schematic that appears to be pretty close, but not exactly my chassis.

james_s · « **Reply #10 on:** February 05, 2020, 02:21:54 am »

The number on the CRT itself is not gonna be much use, it's extremely likely that the same tube was used in other displays, is that a VGA arcade monitor?

trad1984 · « **Reply #11 on:** February 05, 2020, 02:24:38 am »

Yes, I think it is a VGA monitor. I am a newbie, but the game does have a VGA cable output.

james_s · « **Reply #12 on:** February 05, 2020, 02:27:36 am »

I wondered about that due to the "VGA" on the label, I'd guess that same tube got used in numerous VGA PC monitors, which does not really help you here. Most arcade monitors were CGA resolution.

trad1984 · « **Reply #13 on:** February 05, 2020, 03:00:13 am »

Yeah, unfortunately I think I might be out of luck. I haven't been able to find anything on this monitor anywhere. I may have to break down and convert it to an LCD somehow, but that would be a first for me.

PKTKS · « **Reply #14 on:** February 05, 2020, 09:52:42 am »

Quote from: trad1984 on February 05, 2020, 03:00:13 am

Yeah, unfortunately I think I might be out of luck. I haven't been able to find anything on this monitor anywhere. I may have to break down and convert it to an LCD somehow, but that would be a first for me.

Please this is a WILD GUESS based solely upon experience
in doing things like this wo schema

Guessing by position near the transformer I would
say that this parts are a secondary regulator taken
from the mains flyback going elsewhere.

It may have a short which caused this burnt...
A zener or regulator likely near by...w a diode rectifier
also near by... all that seems burnt...

Wild guess

Paul

shakalnokturn · « **Reply #15 on:** February 05, 2020, 01:28:14 pm »

The grey printed tracks on the top silkscreen aren't that easy to follow...
Can you also post a photo of the copper side, from the corner where your burnt components are and including FBT and vertical output IC (the one on the smaller heatsink).
If the FBT isn't the cause of this I'm sure it can be repaired easily enough.
The most obvious cause here would be someone having plugged the connector to the adjustment board incorrectly. (Shifted or flipped.)

Kilo Tango · « **Reply #16 on:** February 05, 2020, 01:53:15 pm »

Maybe check from resistor pads to ground to see if there are any shorts or heavy loads along those lines, that would explain why the resistors blew. Sometimes they used resistors as ( cheap ) fuses, in case of overload the resistor would blow and save cooking the board.

Googling KT-2532 brings up a hit for the "Vintage Arcade Preservation Society" and it is possible that the chassis manufacturer is Kortek ( ? ). Maybe worth looking on here for info as well ?. https://forums.arcade-museum.com/showthread.php?t=337418

Cheers Ken

Kilo Tango · « **Reply #17 on:** February 05, 2020, 02:03:06 pm »

In fact googling Kortek VGA monitor brings up plenty hits, including " Kortek Monitors Tips, Tricks and Cap kits " which might be a useful source of information. Guess they were commonly used in arcade machines

https://forums.arcade-museum.com/showthread.php?t=157123

Cheers Ken

james_s · « **Reply #18 on:** February 05, 2020, 06:33:37 pm »

I would try posting on the VAPS forum or some other arcade forums with a picture of the monitor and see if anyone can identify it for you. This is obviously not a one-off design, there are others out there.

floobydust · « **Reply #19 on:** February 05, 2020, 06:50:44 pm »

Can you look for more numbers, it should have a 14 (for the size 14"), like KT-1402 or KT-1403 kind of thing. It's not easy to find data on Korean CRT monitors.
The CRT tube is made by Orion. The small transformer (line filter) is Kortek part KTV-2532.
You might have to sketch out where some of the burnt parts connect to.
Some Kortek service manuals: https://elektrotanya.com/showresult?what=kortek&kategoria=&kat2=all&page=0

fzabkar · « **Reply #20 on:** February 05, 2020, 07:39:53 pm »

This circuit diagram looks promising:

https://elektrotanya.com/kortek_telcovision_kt1403v_sch.jpg/download.html

trad1984 · « **Reply #21 on:** February 06, 2020, 02:59:07 am »

Thank you everyone for all of the information. I will take your advice and post this on one of the arcade forums as well. I added a few photos of the back side of the board (copper side) as requested. Unfortunately, I couldn't find any other numbers anywhere on the board.

trad1984 · « **Reply #22 on:** February 06, 2020, 03:57:30 am »

Ok, so I think I found it online finally. There is a picture here: https://www.worthpoint.com/worthopedia/merit-telco-monitor-chassis-board-139252646

It looks just like my board and is titled: TelcoVision Type 51 VGA Chassis also labeled KT-1403V which would be a Kortec as suggested above. Now I will just have to see if I can find the manual.

fzabkar · « **Reply #23 on:** February 06, 2020, 04:57:58 am »

Is the schematic I posted not good enough???

trad1984 · « **Reply #24 on:** February 06, 2020, 05:11:42 am »

Actually, yes it works perfectly sorry.

Looks like:
R502 is 1/2W 10K ohm
R503 is 180K ohm
R504 is 100K ohm

And the transistor that i suspect to be bad is a C3198.

You guys are amazing, even with the little amount of detail I was able to provide.


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Author Topic: Need help with Orion 13in Arcade Monitor Repair (Read 5369 times)

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