Pentranic mod cga only ch-288 to Samsung Plano 29”

[1credit]

Hey everybody …

Over in uk it’s not so often to see a Samsung Plano 29” tv tube up
Só I grabed it …

No interest in using as a tv I instantly seperated the tube …

Pentranic are not a high cost chasiss but versatile so

It went on …
Then ooooooooop

It had an issue
Any time the screen flashed
All white even for a nanao second .
Screen would jump UP non ironically
As over voltage from the flyback secondary to the vcc of the vertical output ic … from genaration of the all white screen was causing the over voltage ..


This fault after surfing on the www is documented ..

And arcades had got some shooting
Games with this monitors in and screen would jump every time a shot is fired ..

And beat ups same with some landed specials etc .. any screen flash basically .



I have completed the work around and jumping screen is gone ..

Really nice image but .. a new beast has reared its ugly head !

And I need some advice

Is this moire effect ?

I have a crappy effect that looks like bad vídeo ground but it’s present even with
Vídeo source disconnected off the chasiss with sub bright up..


Anyway here is another pic of the
Set with sub bright right down
Which looks nicer

 

[1credit]

 

[Shop-Dog]

Good morning! Your issue is a different and worse than mine for sure. I have absolutely no idea what is causing that. It's almost as if there's a feedback signal on the video line, causing that artifact. I would surmise it's the workaround, which I need to read up on. It's not Moire per se, as that's a phosphor pixel and image misalignment that affects the entire screen. I have only seen this once and the fix was a replacement of the video IC. I don't think you have this.

Currently, I have a Pentranic chassis model CH-288 15/25k that I can only get very little response from to adjust the Horizontal width. Checked the board over several times now and even the inductor coil has very little effect on width. Thought it might be the tube, as it had serious burn in and was just about dead anyway, so I replaced it. Replacement tube colors a fantastic, but the horizontal issue remains. Not the CRT, but it was needed anyway.

In both of our cases, with the cost of shipping these days, I am seriously thinking about a Wei-Ya eBay chassis for $100. I'd probably have that cost sunk in a 30-year-old chassis with a few parts and the shipping. I just hate disposing of things that I love the challenge of repairing. But this one...has got me.

Cheers,
Neal

 

[1credit]

Yeh I know that feeling ..
I’m not giving in on this chassis

I found the issue on mine resides in the brightness circuit .
But that’s all i can say at moment..
Apart from a short I have also found
That May help you ..

Check this out
Short on pentranic ch 288 heat sync

View: https://youtube.com/shorts/Lioo_Immr_M?feature=share



When the short on the heat sink of a horizontal transistor is grounded out screen jumps to a wider position ..

Maybe you should look to see if you have a plastic insulating sheet behind your horizontal output transistor on the heat sink incase your issue is a short just enough to trap your hori position .

I have recapped my
Chassis now .
And I’m happy with where i can tweak the image too..

 

[Shop-Dog]

@1credit :

THAT"S AWESOME !!!

That's looking really good and I APPRECIATE the information. I'll check it out later this weekend when I have time. I held off on buying a cap kit, as I reached out to Mike @ Mike's Monitor Repair from YouTube. GREAT GUY and got right back to me. Long story short, he said that my chassis and game (Cruis'n) are EGA Medium resolution, and my CRT is CGA, standard resolution. So... I'll never get it to work right.

He's right, A quick pop-in of the monitor part number into google and it is, standard resolution.

Now, I'm still going to see if my Horizontal Transistor has an insulator behind it. I don't recall that it does, but I'll certainly check and get back to you! That would be stellar if that fixed it, then I'd for sure recap it. But alas, I may have the incorrect CRT and Medium resolution one's are made from unobtantium...

 

[1credit]

Do you have a 29” tube ?
I Have some wells d2900 tri sync

You would need correct tube though
Normaly a thompson or matsushita

 

[Shop-Dog]

Unfortunately, I don't. I'm on the hunt....

 

[Shop-Dog]

Now, I'm still going to see if my Horizontal Transistor has an insulator behind it. I don't recall that it does, but I'll certainly check and get back to you! That would be stellar if that fixed it, then I'd for sure recap it. But alas, I may have the incorrect CRT and Medium resolution one's are made from unobtantium...

Do you have a 29” tube ?
I Have some wells d2900 tri sync

You would need correct tube though
Normaly a thompson or matsushita

Unfortunately, I don't. I'm on the hunt....

My chassis DOES NOT have the insulator behind the Transistor..

 

[1credit]

Make sure you get one
Ceramic /card /plastic

Seen all these three diffrent materials

Monitor repair guy said to me
Just try to use what ever was originally used

 

[1credit]

@1credit :

THAT"S AWESOME !!!

That's looking really good and I APPRECIATE the information. I'll check it out later this weekend when I have time. I held off on buying a cap kit, as I reached out to Mike @ Mike's Monitor Repair from YouTube. GREAT GUY and got right back to me. Long story short, he said that my chassis and game (Cruis'n) are EGA Medium resolution, and my CRT is CGA, standard resolution. So... I'll never get it to work right.

He's right, A quick pop-in of the monitor part number into google and it is, standard resolution.

Now, I'm still going to see if my Horizontal Transistor has an insulator behind it. I don't recall that it does, but I'll certainly check and get back to you! That would be stellar if that fixed it, then I'd for sure recap it. But alas, I may have the incorrect CRT and Medium resolution one's are made from unobtantium...

Standerd is cga !

Medium is ega

Hi res is vga