converting a casio TV-880 portable TV from PAL I to PAL B/G

[mdanh2002]

Hi all,

I recently got a Casio TV-880 manufactured for UK from eBay. It is a UHF-only set, supporting PAL I only. Here in Singapore, the set works and is able to tune into stations showing clear color picture, but audio is only white noise because Singapore is using PAL B/G.

My researches on Wikipedia (see https://en.wikipedia.org/wiki/PAL#PAL_broadcast_systems) and this website (https://www.edaboard.com/thread222963.html) show that it may be as simple as changing a crystal (or retuning the LC oscillator) from 6MHz (for PAL I) to 5.5 Mhz (for PAL B/G).

I opened up the unit and quickly identified a crystal (marked as red in the attached photo). However, with my oscilloscope, I measure the frequency and it is 4.43Mhz (the PAL color subcarrier), not the sound carrier.

I found a service manual online for a similar model, TV-770 (see attached). There are 4 different PAL variants for this model:

TV-770C (PAL B / G, H)
TV-770D (PAL I)
TV-770G (PAL M)
TV-770N (PAL B / G, H)

Studying the block diagram on page 4 and the part list on page 8 (section Tuners), I realized that the 4 variants are using 3 different types of tuner:

TEPE5-01 for PAL B/G/H
TEPB5-05 for PAL I
TEPU5-02 for PAL M

Does this mean that there is no hope of converting my set to PAL B/G since the tuner is soldered on board? Also is there any way to convert this set to a VHF/UHF set, or is it in the tuner as well? I am hoping that Casio used same components for their different models and just changed the OFF/VHF/UHF switch to prevent tuning into VHF on their UHF models.

Also what is the part in yellow in the photo for? I am assuming it is to calibrate or tune something.

Thanks for any advice

 

[Nigel Goodwin]

If it uses crystal filters inside the tuner/IF then you simply remove the tuner/IF, disassemble it,. and chenge the filters - then put it back in.

But are Singapore continuing to use the obselete analogue TV system?, most of the world is changing to digital.

 

[mdanh2002]

Hi Nigel,

Do you think the tuner (the part with metal cover and a white sticker on it in the photo) can be disassembled to replace the crystal filters and reassembled? I am asking because it looks like there is no gentle way to open it except to break the cover. If it's too hard, I will just keep the set and use with my home made transmitter and broadcast in PAL I.

As for analog TV, it is still common in Singapore (both VHF/UHF). Digital TV is still under trial and won't replace analog TV until at least 2015. For me, as long as I can watch a clear picture, it doesn't matter which is used

 

[Nigel Goodwin]

Hi Nigel,

Do you think the tuner (the part with metal cover and a white sticker on it in the photo) can be disassembled to replace the crystal filters and reassembled? I am asking because it looks like there is no gentle way to open it except to break the cover. If it's too hard, I will just keep the set and use with my home made transmitter and broadcast in PAL I.

You need to disassemble the can, often these are soldered together.

 

[mdanh2002]

You need to disassemble the can, often these are soldered together.

Thanks Nigel. I will try.

Just one more question, is there any hope of modifying this set to support VHF as well, instead of just UHF?

 

[Nigel Goodwin]

Thanks Nigel. I will try.

Just one more question, is there any hope of modifying this set to support VHF as well, instead of just UHF?

If it's not got a VHF tuner, then no chance - unless you can buy a replacement tuner which has VHF inside as well?.

 

[mdanh2002]

If it's not got a VHF tuner, then no chance - unless you can buy a replacement tuner which has VHF inside as well?.

Thanks,

Btw, do you know how to improvise an antenna socket on this TV? Currently it only has a telescopic antenna with no antenna socket. Here in my room the reception is very bad. I use a crocodile clip to connect from the outdoor antenna to the telescopic antenna and the picture quality is still bad (although there is some improvement). I am pretty sure the outdoor antenna is fine, because when used with the antenna socket in my home LCD TV, the picture is great.

 

[Nigel Goodwin]

Presumably you could connect directly to the tuner?.

 

[mdanh2002]

Presumably you could connect directly to the tuner?.

Hi Nigel,

I was thinking so too, but I am still wondering why just using crocodile clip does not work

 

[Nigel Goodwin]

You need to connect to the chassis of the tuner as well.

 

[lcys]

converting a casio TV-880 portable TV from PAL I to PAL B/G ?

Did you manage to convert from PAL I to B/G ?
I have the same Tv and the same issue to fix.
Just bought few Tv s from UK and I guess I will have to find a solution.
If I can't I have a buddy who's fixing Tv s ...
I'm pretty much confident that he'll be able to fix that 5,5-6-6,5 Mhz voice carrier problem.
I use to fix this type of problem in VCR s like 10+ years ago but that was simple enough...
Just had to buy a little PC board and make 3 connections and it was good enough...
I understand here the main issue is that you have to open the "can" around the tuner...
I was wondering if you would use a heating source like a cigarette lighter to heat up the "can" would help to remove the metal around the tuner in one piece without bending it ?

 

[mdanh2002]

Hi,

Unfortunately I am unable to fix it as the tuning band (UHF/VHF) and audio sub-carrier frequency is all in the tuner. I may be able to try the heating method you mention, but I am afraid it may damage sensitive parts on the board. Not easy even for somebody with TV repair experience - portable TV and big CRT TVs are very different. Even if you manage to reach the inside of the tuner, there is no guarantee that replacements are available - many are SMD components Unless you can find a CASIO portable TV parts supplier, purchase the proper tuner from them and replace it entirely.

Visit my article which I review this issue at **broken link removed** and there is a link to various Casio portable TVs service manuals at the end. If you are inclined to repair it, go through the manual carefully so that you know where to troubleshoot when things go wrong.

The next time I purchase an analog portable TV from eBay (most are from US and UK), I will make sure to ask the seller for a photo of the back of the unit, which will indicate the supported tuning bands and TV system. Many of those from the UK are PAL I, UHF only while those from US are VHF/UHF but NTSC only. Check carefully before you buy

 

[lcys]

I was asking a friend about this matter.

Actually I bought a tv just like this and in few days I will have it fixed by my friend.

He sayed that you should have to change some of the 3 ceramic filters [ those orange 3 pin stuffs ] next to the yellow square in the picture.

It might work with only one changed but there is a a possibility that you might need to change more than one filter.

You might be able to change those...there are very cheap as well. I will get back to you as soon as the Tv will be ready to let you know the updates.

Good luck!

 

[mdanh2002]

Hi lcys, Thanks for sharing. I will have another look at my TV with my oscilloscope again and see if that can be done. Do update me on your progress! Thanks