Swapping CRTs question


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Swapping CRTs question

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t0nito
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Aug 22, 2014, 10:46 AM

Post #1 of 7 (1780 views)
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Swapping CRTs question	Can't Post

Hi I my sister brought me her TV and asked me if I could fix it, it's a CROWN CTV 8051 TX. I can't find any info anywhere about it and no circuit diagram.

I can only find a site that claims it to be a totally different chassis.

On the chassis there's written eurocir 971s but can't find anything with that reference.

There are 3 problems with it:

1- There is no blue channel except for OSD and teletext, following the traces both the teletext decoder and OSD's RGB output directly to the RGB socket to the CRT without going through the jungle IC.

Both RGB SCART input and tuner have no blue, snow is yellow as well. I suspect the Jungle IC is faulty.

2- The image was blurry, turning the focus pot to max helped but it's not quite there yet, I suspect the flyback is failing.

3- Image is dim with contrast and brightness to max, even turning the screen pot up shows raster lines but image is still not very bright.

(Can the flyback also cause the picture to become dim?)

I suspect the CRT is on its last leg.

The original CRT is a ORION A48JLL80X01, I have a dead TV with a very good and bright CRT its a ORION A48JLL90X01 they look the same size. The CRT neck plug is identical.

Since I can't find any info on these CRTs I wonder if they are swappable (complete with yolk), is there any difference between them?

Thanks

(This post was edited by t0nito on Aug 22, 2014, 11:36 AM)

Ron.M
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Aug 22, 2014, 6:21 PM

Post #2 of 7 (1755 views)
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Re: [t0nito] Swapping CRTs question [In reply to]	Can't Post

t0nito;....

I have never heard of that brand of TV , but , I think I can still help you out...

#1)...
Since you say that you ARE getting blue on OSD and teletext , that would rule out the CRT as that part of the problem(s)...
Looks like an IC is bad..

#2)..
Since the focus IS adjusting , the chances that the flyback is bad are slim to none & slim left town... Unsure

..

#3)..
Everything points to a BAD CRT !!!

Quote

(Can the flyback also cause the picture to become dim?)

Yes ...IF the screen control is adjusted too low...
However , when adjusting the screen control , the brightness will increase with out giving raster lines till the brightness is excessive..
And usually you will not see a change in the focus..
I seriously think your flyback is OK ...

Quote

I suspect the CRT is on its last leg.

BINGO !!!
Yep , looks that way to me also...

Quote

Since I can't find any info on these CRTs I wonder if they are swappable (complete with yolk), is there any difference between them?

Even IF they are , it'd be a WASTE of time & energy to do that as you have other problems with that TV that may not be able to be fixed... Unsure

...

Good Luck..

Later.Ron.M... Cool

....
Veteran & Retired TV technician

(This post was edited by Ron.M on Aug 22, 2014, 6:23 PM)

jts1957
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Aug 22, 2014, 6:49 PM

Post #3 of 7 (1746 views)
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Re: [t0nito] Swapping CRTs question [In reply to]	Can't Post

Try 11AK19B-1

http://wiki.arcadeotaku.com/..._designation_systems

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Location: Far, Far Away

t0nito
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Aug 22, 2014, 6:52 PM

Post #4 of 7 (1745 views)
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Re: [Ron.M] Swapping CRTs question [In reply to]	Can't Post

Thanks for the input :)

Well since the IC is a cheap part and I have the other CRT just laying there waiting to go to the trash (from that old Grundig I gave up on, remember?) I guess I don't have much to lose. And it will be a learning experience. If after swapping the IC full colour comes back but remains dim I'll try the swap.

t0nito
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Aug 22, 2014, 6:55 PM

Post #5 of 7 (1744 views)
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Re: [jts1957] Swapping CRTs question [In reply to]	Can't Post

In Reply To

Try 11AK19B-1

http://wiki.arcadeotaku.com/..._designation_systems

Thanks.

That's what showed up when I searched for it. That chassis is completely different. Must be some mistake.

Very useful and informitive link. According to the info both CRTs have common optical, electrical and mechanical characteristics and are the same size. So I guess all is well. It's not very clear though, the difference between the "80" and "90" part other than being from different family members (whatever that means...)

(This post was edited by t0nito on Aug 22, 2014, 7:54 PM)

t0nito
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Aug 25, 2014, 5:41 PM

Post #6 of 7 (1713 views)
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Re: [Ron.M] [jts1957] Swapping CRTs question [In reply to]	Can't Post

Hi, just giving a little update on this.

The CRT swap was a success! The picture is pretty bright and sharp! The other CRT was in fact worn out, (never seen that happen before) but then again I'm not a TV tech :P.

It was a really fun process, I also had to desolder the old H/V deflection wires from the yolk and resolder from the other CRT because the plug was different, I also reinstalled the degaussing coil and shield wiring from the old CRT. How fun!!!

Now the bad news, I ordered the IC, didn't notice there was a difference, the original is a TDA8361 and the ordered one was a TDA8361A I installed it and the flyback wouldn't fire. It did have audio and the volume worked, but in the end it was just an oversized radio.

I checked and double checked the pin soldering to make sure there was no short or bad connections, I also checked if I hadn't drop any solder on the board by accident but nothing.

So I reinstalled the old IC and it fired up again with the original symptom, of course.

I read on one site that the TDA8361A is retrocompatible with the TDA8361 but not the other way around but it doesn't seem to be the case. This time I ordered the correct part, I hope next time it will turn out better.

Since I'm fiddling with this thing, I also added a 3.58 MHz crystal, so now the TV also supports NTSC through the AV input :)

Here are some pics of what it looks like now:

(This post was edited by t0nito on Aug 25, 2014, 5:56 PM)

t0nito
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Sep 23, 2014, 8:34 PM

Post #7 of 7 (1599 views)
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Re: [t0nito] Swapping CRTs question [In reply to]	Can't Post

Hi, just wanted to make an update to share the results.

So I finally replaced the IC and tube and here are the results:
(Ignore the moire pattern that's from the camera)

Thanks!

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