Seeltech ST2468DHD 24" LCD HD TV Standby only - help needed!

[joste]

Re: Seeltech ST2468DHD 24" LCD HD TV Standby only - help needed!

Hi vaneno,
Thanks, it is always a pleasure to see someone was able to use our inputs successfully.

Regards,
Joste

[vaneno]

Re: Seeltech ST2468DHD 24" LCD HD TV Standby only - help needed!

Hello. Sorry for revive topic. Yesterday i fix another tv with same faill. Mine was a blusens , 22", same MB. It was remaining allways on stand-by. After reading this, im going directly for 1n4001 and 3 caps 470uF, and fix it on half hour . So, many many many thaks for share.

[j2c2grabels]

Re: Seeltech ST2468DHD 24" LCD HD TV Standby only - help needed!

My peekTON 15.6" TV have the same mB and almost the same problem. I replced the 2 1N4001 that seem to be good (testing diode function of my old Fluke 77 multimeter) and my TV is runnig OK again !
Thank you very much for your explanations.

[jacouille]

Re: Seeltech ST2468DHD 24" LCD HD TV Standby only - help needed!

bjr, I have a lcd seeltech 2468 with the same failure can say vs el component that I need to change the map to repair this tv seeltech
thank you very much
I am in France

[joste]

Re: Seeltech ST2468DHD 24" LCD HD TV Standby only - help needed!

Wow, failed diode? I thought you checked those. Anyway, enjoy your fixed TV! I guess talking to the company actually worked. Wow.

Hi Tom66,

Yes, you're right, all diodes where checked and they measured OK. But, once the current hits hard (on startup), they kinda "change their mind". Who knows, maybe the caps (also looking good, no leak, not bulged) have lost a lot of their capacity, so the switch couldn't give current needed to power up the CPU.

Whatever, I just can't take my eyes off the screen. I've missed my TV so much and I really am happy to have it back.

Yes, talking to people can often help much. That's why I appreciate this forum and your help.

Thanks again to all of you guys and certainly you, Tom66

[tom66]

Re: Seeltech ST2468DHD 24" LCD HD TV Standby only - help needed!

Good news! The set has been successfully repaired!

I had a telephone conversation with a tech from the company that is official importer and wholeseller of this brand and he was very kind to share his knowledge and experience. He said that this failure is very common for this model and that in more than 60% of all cases it is the diodes around the coils on the left hand side (SMPS). These two 1N4001 have been looking good both in Standby mode and disconnected. But, the catch was in what happens once the current hits them. So, I followed his advice and changed the diodes with 1N4007C. Once my soldering iron was hot, I took the oportunity to change their 470uF/16V caps just in case.

The result was as follows:

- TV turns on quicker than before

- FLV media files are displayed without any problem, which wasn't the case before the repair. In fact, the set finally broke while I was playing the same FLV file. It is possible that CPU requires more current to decompress certain contents and that was the moment when the diodes (and possibly caps) finally failed.

I have also found the exchange mainboard, but its price of 140€ (VAT and shipping included) but luckily I didn't need it.

So, guys, thank you for reading this and thanks for the help you provided.

See you soon on the forum

Cheers!

Wow, failed diode? I thought you checked those. Anyway, enjoy your fixed TV! I guess talking to the company actually worked. Wow.

[joste]

Re: Seeltech ST2468DHD 24" LCD HD TV Standby only - help needed!

Good news! The set has been successfully repaired!

I had a telephone conversation with a tech from the company that is official importer and wholeseller of this brand and he was very kind to share his knowledge and experience. He said that this failure is very common for this model and that in more than 60% of all cases it is the diodes around the coils on the left hand side (SMPS). These two 1N4001 have been looking good both in Standby mode and disconnected. But, the catch was in what happens once the current hits them. So, I followed his advice and changed the diodes with 1N4007C. Once my soldering iron was hot, I took the oportunity to change their 470uF/16V caps just in case.

The result was as follows:

- TV turns on quicker than before

- FLV media files are displayed without any problem, which wasn't the case before the repair. In fact, the set finally broke while I was playing the same FLV file. It is possible that CPU requires more current to decompress certain contents and that was the moment when the diodes (and possibly caps) finally failed.

I have also found the exchange mainboard, but its price of 140€ (VAT and shipping included) but luckily I didn't need it.

So, guys, thank you for reading this and thanks for the help you provided.

See you soon on the forum

Cheers!

[joste]

Re: Seeltech ST2468DHD 24" LCD HD TV Standby only - help needed!

To be honest with you, I'd sell the whole set for a hundred quids. There's a small superficial scratch on the lower lefthand part of the panel, but you can't even notice it once the screen goes on.

I know you're not interested, I wrote this for other folks who might be reading this thread.

I'll post panel reference later, and power supply/invertor board is still in mint condition!

Not to forget IR RC , still with original batteries!

[tom66]

Re: Seeltech ST2468DHD 24" LCD HD TV Standby only - help needed!

Nope, everything is SMD and not a single socket and chip that can be removed. I guess this makes the whole operation hardly possible.

Simply, I got out of patience and if I don't find some "instant" solution (like exchange MB or something), I'll give it up.

I'll give a call to importer and wholesale distributor to hear their say. Maybe thay still can help a bit, who knows.

Good luck. Your best bet right now may be to extract the 24" LCD panel and CCFL tubes. The tubes sell for £3 - £8 each (there are usually 10-15 in a small set like yours) and the 24" LCD would sell for around £100, since it's 1080p. Then save up the money and buy a set which has an easy to get service manual.

[joste]

Re: Seeltech ST2468DHD 24" LCD HD TV Standby only - help needed!

Nope, everything is SMD and not a single socket and chip that can be removed. I guess this makes the whole operation hardly possible.

Simply, I got out of patience and if I don't find some "instant" solution (like exchange MB or something), I'll give it up.

I'll give a call to importer and wholesale distributor to hear their say. Maybe thay still can help a bit, who knows.

[tom66]

Re: Seeltech ST2468DHD 24" LCD HD TV Standby only - help needed!

What do you think of bad (or damaged) eeprom dump? Can it cause such a problem? I am prone to believe so. Any advice?

Thanks again.

There is usually a small chip (EEPROM) in a socket which can be removed. (It is not surface mount.) *Carefully* use a screwdriver to wedge it out. Put it in a safe place. Some TVs will turn on without this, others won't. However, I'm inclined to believe this won't fix it as your problem is intermittent.

Reading and writing the EEPROM is not easy although I have done it before using a PICkit 2.

[joste]

Re: Seeltech ST2468DHD 24" LCD HD TV Standby only - help needed!

What do you think of bad (or damaged) eeprom dump? Can it cause such a problem? I am prone to believe so. Any advice?

Thanks again.

[joste]

Re: Seeltech ST2468DHD 24" LCD HD TV Standby only - help needed!

Yes, I know what you mean, Tom. In fact, on the user manual there's not a single word about helpdesk, nor any instruction if the set gets broken! There is just some name and address of (presumably) importer and/or wholesales distributor. Not a single telephone number. Well, I know: when I bought the TV I didn't ask questions about maintenance, I was really self-confident, but now what?! Never mind, I'll track it down and find some contact, I'll try to get that service manual and then we'll fix it (if only BGA is still alive and kickin').

Funny, but the part of MB with DVD connectors still has 5V even in Standby mode, but TV doesn't power on?!

Just in front of two coils we have mentioned earlier there are two SMD diodes (respectively) and there's 3.3V and 5V voltage in Stby mode. From there on it gets hardly possible to track the voltages due to a load of SMD components squeezed one against other on a very small surface. There's a couple of SMD transistors looking good, but who knows what happens when the current strikes?!

You're right, Tom: without a service manual or at least schematics it is almost impossible to fix this board.

I hope someone would see my MB and suggest from what other brand was it rebadged. That would help a lot. I can't imagine that Seeltech has made an original design here, and still the brand is untraceable?!

[tom66]

Re: Seeltech ST2468DHD 24" LCD HD TV Standby only - help needed!

The only way forward is to really get a service manual, but I have no clue. In very rare cases, calling the company up and asking nicely can do this. I can find only a few references to Seeltech on the internet, which means it is almost certainly a rebadge of other TVs. For example Vestel makes a lot of TVs for the Goodmans, Matsui, Nikkai, AcousticSolutions, etc. brands - they are all the same. If I could get a service manual I would be able to help more. But right now I am just stuck.

[joste]

Re: Seeltech ST2468DHD 24" LCD HD TV Standby only - help needed!

No doubt they both work good. There are two connectors, one for IC RC and other for top buttons.

If you take look of my previous photo (better resolution than this one), you'll find these connectors at the top of the MB. Blue connector (the third one from left to right) is for RC, and white one next to it (fourth from left to right) is for top buttons.

[tom66]

Re: Seeltech ST2468DHD 24" LCD HD TV Standby only - help needed!

Yes, but not more often than with RC.

So RC is probably good.

Can you get a pic of the connector which goes from IR to main board. Also one which goes from side buttons to main board. (They might be on the same connector.)

[joste]

Re: Seeltech ST2468DHD 24" LCD HD TV Standby only - help needed!

Is there a way to turn it on without the remote control? (For example, on the side panel.)

Yes, but not more often than with RC.

[tom66]

Re: Seeltech ST2468DHD 24" LCD HD TV Standby only - help needed!

At the moment, I am really at a loss. Is there a way to turn it on without the remote control? (For example, on the side panel.)

[joste]

Re: Seeltech ST2468DHD 24" LCD HD TV Standby only - help needed!

To answer your questions first:
This is not a positive ground chasis.
When the TV powers on, then it works without any problem, everything is there: picture, OSD, sound, backlight... Then, after half a minute or so it goes Standby just like that. Afterwards, no matter how hard I try, I can't power it on again. If I disconnect the mains and try ON button, it just might power on again, but not more often than once or twice per day. So, let's call it an "intermittent fault".
I have to agree about BGA - I have also applied some physical pressure on the heatsink and it never gave any positive result, so I guess that bad joints on BGA pins is ruled out?

Selling the set wouldn't really be an option, because I've seen some more of these with the same fault out there and it seems nobody is interested in.

This TV is a 1080P with USB port (with DivX and many other compressions reading capability, rich with codecs), HDMI, SCART, RCA, S-video ,coaxial and digital out... I was really happy with this TV, also SAMSUNG tuner used to receive even a bit weaker signals without problem. I'm gonna miss it, really. Yes, the set was bought for Christmas two years ago.

I have to admit that so far I haven't seen a MB that reminds of this one. It would be hard to find the replacement.

If you'd still give it a try, just let me know. I have to give up here, at least for now. I have to fix my wife's car. This summer things just seem to never stop getting broken.

Thanks for your prompt help, Tom66 and looking forward to hear from you again.

John

[tom66]

Re: Seeltech ST2468DHD 24" LCD HD TV Standby only - help needed!

In fact, my first thought was to change the mainboard, but where (and how) to find it? I'm not bad myself in searches over the Net, but never managed to find anything about this MB; Can you give me any model or reference to search for? That would be great.

Other thought: since we don't live too far away from each other, I'd be glad to mail this MB for some hot air resoldering if you'd accept?

I'd give it a go, but I'm thinking it's a simple fault, and that the BGA isn't at fault in this case. It seems to be intermittent and BGA faults rarely are.

Voltages relative to 12V. Very odd. Can you check continuity between +12V and case of TV? It should be very high. It might be a positive ground case but I don't think I have ever seen a TV like that.

When the TV does power on, does it work properly? Do you get a picture? Or does it just leave standby?

I got a hit: http://www.shopjimmy.com/polaroid-3550c-main-unit.htm however although it looks similar, it's not identical.

Unfortunately you may be looking at a manufacturer specific part and this will be difficult if not impossible to source.

You best bet may be to sell the TV as-is to someone who knows what they are doing. (Not me!) A 24" LCD TV with a working screen but power problems sells for around £100 on eBay.

A question; approx what year did you buy the TV & when was it manufactured (if known)? Maybe similar TVs from this date would use the same board.