Author Topic: 13” K7203 monitor - wavy picture/interference  (Read 366 times)

Offline Spicules

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13” K7203 monitor - wavy picture/interference
« on: November 13, 2022, 06:28:05 PM »

Got this unit dead; checked the pcb and there was a cluster of caps with one bulging in the corner.

Replaced some caps in that area, and powered on. High pitched squealing noise made me think its the flyback.

new flyback does not change, so I do a complete cap kit and go over the traces for loose connections etc.

I do see a transistor near the flyback on a small heatsink that is so loose, it felt like it would fall out of the board.

So I redo a bunch of connections, and do some jumpers (the pads were burned on the transistor)

After that, it will power on and display raster. 

I can get to to display video with my Test pattern generator, but there's slight, small horizontal lines in the video like as if you were watching a VHS and the tracking was a little off.

There's horizontal "interference" lines is the best I can describe.

I've already tried adjustments, but this doesn't look like an adjustment to me.

I read that C008 (471uf/1kv) causes problems with these and my cap kit didn't include this non-electrolytic cap.

I’ve ordered that cap for now and that’s my only lead at the moment.



Anyone ever fix this issue?

Link to video of problem:


https://imgur.com/a/IZlqPqs
Vids:
"Chewlix" Vewlix knockoff; Dynamo HS-27 w/ Area 51/MaxForce;  Strider (DE "Commando" conversion) ; Centipede Cabaret;  Tempest,  Irem "Madonna" ; Sega Blast City w/ MisterFPGA; Shinobi (Track&Field Conversion) ; Sega Naomi Universal with Piforce/Net Dimm;

WTB/WTT: HOTD2 Dedicated; candy cab or candy knockoffs; Outrun cabaret

- I am a former TV tech and can repair and re-cap CRT and LCD monitors in my area.

Offline FUNWIZ

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Re: 13” K7203 monitor - wavy picture/interference
« Reply #1 on: November 14, 2022, 01:42:17 AM »
Not sure what all caps you have replaced as you’re kind of vague that you replaced some of the caps. Did you replace the 220µF 400 V cap C005?  Also unplug your degaussing coil during testing to make sure it is not staying on.  C101 and C102 100µF at 160 V. TP1 121V. TP2 24V. TP3 12V. TP4 8V. JP301 16V. U101 pin3 5V.  GL
Pins: Allied Leisure, Astro Games, Atari, Bally, Bell Games, Chicago Coin, Chicago Gaming, Data East, Game Plan, Gottlieb, JJP, Midway, Mr Game, Mylstar, Nuova Bell, Premier, Sega, Sterns, Williams, Zaccaria. Jukes: AMI, NSM, Rock-Ola, Rowe, Seeburg. Vids: Atari, Capcom, Data East, Exidy, Gottlieb, Midway, Namco, Nintendo, Sega, Sente, Stern, Taito, Universal, Williams.

Offline Spicules

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Re: 13” K7203 monitor - wavy picture/interference
« Reply #2 on: November 14, 2022, 02:15:04 PM »
I went through the caps and checked for loose connections etc, and found no issues; then I swapped back to the OLD Flyback, and that got rid of the problem.  Going to let it run for a few more hours and see if it stays.

This was the one from arcadepartsandrepair.com ; maybe it is better for the 19" and not the 13"?

But to clarify - I replaced all electrolytic caps, except the BP cap at C14 (1ouf 100v) that the kit did not come with.

Also went over loose connections and replaced flyback that did not fix and maybe even caused an issue?

Vids:
"Chewlix" Vewlix knockoff; Dynamo HS-27 w/ Area 51/MaxForce;  Strider (DE "Commando" conversion) ; Centipede Cabaret;  Tempest,  Irem "Madonna" ; Sega Blast City w/ MisterFPGA; Shinobi (Track&Field Conversion) ; Sega Naomi Universal with Piforce/Net Dimm;

WTB/WTT: HOTD2 Dedicated; candy cab or candy knockoffs; Outrun cabaret

- I am a former TV tech and can repair and re-cap CRT and LCD monitors in my area.

Offline FUNWIZ

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Re: 13” K7203 monitor - wavy picture/interference
« Reply #3 on: November 14, 2022, 05:12:32 PM »
Could be a bad flyback or they gave you the wrong one, they both use the same one.
Pins: Allied Leisure, Astro Games, Atari, Bally, Bell Games, Chicago Coin, Chicago Gaming, Data East, Game Plan, Gottlieb, JJP, Midway, Mr Game, Mylstar, Nuova Bell, Premier, Sega, Sterns, Williams, Zaccaria. Jukes: AMI, NSM, Rock-Ola, Rowe, Seeburg. Vids: Atari, Capcom, Data East, Exidy, Gottlieb, Midway, Namco, Nintendo, Sega, Sente, Stern, Taito, Universal, Williams.

Offline Spicules

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Re: 13” K7203 monitor - intermittent shutdown
« Reply #4 on: December 03, 2022, 09:41:06 PM »
Now intermittently works.  Stuck it in the cocktail I intended it for, and it was working great for a few days.  Then it would stop.  I'd put it on the bench and it would work... back in the machine...stop working ... and so on.

checked this on the bench when this happens, it has ~ +23v at TP2 , 12v at TP3 , 5v at P100 , ~7.6v at TP4  the correct testpoints and B+ TP1  is around 150 (much higher than the 121 needed)

The other voltage test points seem on point, and I'm thinking its in HV shutdown but I don't know what's causing it.

Vids:
"Chewlix" Vewlix knockoff; Dynamo HS-27 w/ Area 51/MaxForce;  Strider (DE "Commando" conversion) ; Centipede Cabaret;  Tempest,  Irem "Madonna" ; Sega Blast City w/ MisterFPGA; Shinobi (Track&Field Conversion) ; Sega Naomi Universal with Piforce/Net Dimm;

WTB/WTT: HOTD2 Dedicated; candy cab or candy knockoffs; Outrun cabaret

- I am a former TV tech and can repair and re-cap CRT and LCD monitors in my area.

Offline Spicules

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Re: 13” K7203 monitor - wavy picture/interference
« Reply #5 on: December 13, 2022, 10:53:29 AM »
Shelving this one;  Put a 19" K7000 chassis on this 13" tube.  Pretty much drops right in (I had to add a pin to plug the CRT ground to the neckboard) and works great now.

Will revisit this chassis another day.
Vids:
"Chewlix" Vewlix knockoff; Dynamo HS-27 w/ Area 51/MaxForce;  Strider (DE "Commando" conversion) ; Centipede Cabaret;  Tempest,  Irem "Madonna" ; Sega Blast City w/ MisterFPGA; Shinobi (Track&Field Conversion) ; Sega Naomi Universal with Piforce/Net Dimm;

WTB/WTT: HOTD2 Dedicated; candy cab or candy knockoffs; Outrun cabaret

- I am a former TV tech and can repair and re-cap CRT and LCD monitors in my area.