Panasonic TX-24A1UN CRT Sound and Input problem.

[hugocarmo]

Hi.

I´ve been given an old CRT from Panasonic, it´s almost new, it was storaged and almost not used since bought.
It is imaculate inside, almost no dust or debris inside.
The picture is good, but I have no left sound channel, I tried all the inputs, outputs, even on headphone jack. In AV2 I hear sound from right channel but no image, on tv tuner only right sound channel, the same for AV1.
So I started to look for a service manual, I found one, and started from the beginning.
Most of the times the caps are the problem so I orderer all the caps for all boards, wich I replaced, one by one, not all because I misunderstood some of them and ordered polarized when they were non polarized, of course those I didn´t replaced, but I can say that I have 70% of all boards, with new capacitors, all almost nichicon.
Well, the problems remains, no left sound channel, no image in AV2, only on AV1...
Some of You have any experience with this model? It´s a Alpha 2 Chassis, I will upload some pictures and the service manual.

Thank You all in advance,

Hugo from Portugal!!

Service manual GDrive link https://drive.google.com/file/d/1TU7iXHmg4P0YWFN9Y53PmxeDpy0ohcTl/view?usp=sharing

[simpsons]

Hi Hugo

Looking at the UK TX24A1 version, this is quite a sophisticated TV which requires the original remote control and copy of the Operating Manual to access the many functions and options.

Do you have both?

Chris

[Welsh Anorak]

It's unlikely capacitors would have been to blame here.

Chris is right - it could be something as simple as the balance control being to one end. If not then I'd be looking at the AV switching chip.

[Maarten]

The sound signal should be traceable.

[hugocarmo]

Originally Posted by simpsons

Hi Hugo

Looking at the UK TX24A1 version, this is quite a sophisticated TV which requires the original remote control and copy of the Operating Manual to access the many functions and options.

Do you have both?

Chris

Hi Chris.
Thank You for your answer.
I don´t have the original remote, but I found one and aleady bought it, I´m waiting for it to arrive from Germany.
The Operating manual I can´t find it anywhere, only the service manual.

I´ll try with the original remote when it arrives.

Thank You.

[simpsons]

Hi Hugo

To see the functions of the original remote control, download the Panasonic TX24A1 Manual (User Guide).

This is the UK version of your set and whilst it may not include some of the specific adjustments for example, the multi system capability, for audio, the dual mono, bilingual mono, Stereo sound channel selection, etc, etc, are shown.

Chris

[hugocarmo]

Originally Posted by simpsons

Hi Hugo

To see the functions of the original remote control, download the Panasonic TX24A1 Manual (User Guide).

This is the UK version of your set and whilst it may not include some of the specific adjustments for example, the multi system capability, for audio, the dual mono, bilingual mono, Stereo sound channel selection, etc, etc, are shown.

Chris

Thank You Simpsons.
I downloaded it, now I´m expecting the remote to arrive for further testing.

Best regards,

Hugo.

[hugocarmo]

Hi.

I have some updates about this repair.
As I said I was waiting to receive the original remote that I found online.
After receiving it it didn´t work.
I opened it, tested all components, replaced the two capacitors, and came to the conclusion that was the crystal ressonator that was bad.
It is a CSB420P, I ordered one and after replacing it, the remote started to work perfectly!
The remote has some tracks that are in bad shape, I scraped the lacker and applied new one, I think it will last for a few years!!

Now, the sound problem... I ordered some IC´s, STK4392, AN5836, TDA3803A, M51321P, and PCD8582DP, I found them cheap so ordered all.
After replacement of all of them, I resolved the sound problem.
Now I have sound on both channels, this tv has a great sound quality indeed!
But the AV2 scart input remains with the problem that only sound is heared.
The screen is gray with no picture at all, only sound.
Something curious, when I have AV1 connected if I go to any channel in tuner the image is the same as AV1, is it normal?
I post images and a video in the end of the post.

Thank You very much!

Hugo.


https://vimeo.com/1085978165?share=copy

[marceljack]

This as well as no picture on AV2 is probably due to a problem in the AV switching (video circuitry always connected to AV1, even when in AV2 or tuner position).
Is there not a connection between two pins (due to an excess of solder for example)

[hugocarmo]

Originally Posted by marceljack

This as well as no picture on AV2 is probably due to a problem in the AV switching (video circuitry always connected to AV1, even when in AV2 or tuner position).
Is there not a connection between two pins (due to an excess of solder for example)

Hi marceljack.
I think not, I replaced the AV switching chip and the problem remains.
But let me explain better, if I connect the antenna I can tune analog TV channels.

Thank You.

[Welsh Anorak]

Are you sure that AV2 isn't configured electronically for RGB? Some were.

[hugocarmo]

Originally Posted by Welsh Anorak

Are you sure that AV2 isn't configured electronically for RGB? Some were.

I can try connecting another type of equipment to AV2, maybe a vcr or a PS2 to test.

Thank You.