Sylvania LC320SS9 Flashing Green LED

[Mr Bill]

A friend of mine pulled this tv from a dumpster. When you turn it on the green led flashes then goes back to standby. I pulled every cap and checked the capacitance and esr and all are below 1 ohm. Only the 10uf and smaller caps were higher (1-2 ohm). Then we started checking diodes and 3 that are right above the transformer were shorted out (0.001), this is in and out of circuit. The numbers on the diode were 867-15. Pulled a datasheet and it states its a high voltage schottky barrier diode (3 amp). On an impulse he went to radio shack and picked up 3 (3 amp) diodes and we soldered them in. The tv did come to life but for only 10 seconds. The 3 radio shack diodes are now shorted out.

So now i'm trying to find the correct replacement from digi key and mouser and i'm not feeling real comfortable that i'm finding the correct replacement. And, is there anything that could cause the diode to blow other than the radio shack one wasn't rated for the job? I uploaded the datasheet for quick reference.

Thanks

[Th3_uN1Qu3]

Re: Sylvania LC320SS9 Flashing Green LED

In the datasheet it says "super high speed switching". Afaik, Radio Shack doesn't sell special diodes like that, only general purpose parts suitable for rectifying mains and not more than that.

The datasheet is pretty scarce, it does say high speed switching but doesn't mention reverse recovery time, a lot of stuff is missing... Anyway, i did a parametric search at digikey and this is the only diode i came up with that is in stock and you can buy in quantities of 1. It's a schottky but it should work just fine, it matches the original in all aspects. http://search.digikey.com/us/en/prod...16-1-ND/654568

[tom66]

Re: Sylvania LC320SS9 Flashing Green LED

Ugh. That looks awful for a power supply. It looks like the three diodes are in parallel. Great way to encourage thermal runaway. And those tiny heatsinks. It's clearly built worse than a Vestel, I thought I would never say that but it is. If you fix it, it would be highly advisable to make the heatsinks bigger, or add a fan to cool it. I can't imagine any of these cheap sets living past 2-3 years.

[Mr Bill]

Re: Sylvania LC320SS9 Flashing Green LED

Tom do you think thermal runaway would be a likely cause for the 3 original diodes to have failed?

[tom66]

Re: Sylvania LC320SS9 Flashing Green LED

Tom do you think thermal runaway would be a likely cause for the 3 original diodes to have failed?

Highly likely. But you can check for shorts. After removing the diodes, check the cathode end to case ground. Should be high resistance.

[Scenic]

Re: Sylvania LC320SS9 Flashing Green LED

Just by the way... The insides of this thing look one heck of a lot like a 22" (1680x1050) Funai LCD TV I dumped about a year back

That one had a cracked panel, and the T-CON was part of the mainboard, with 2 flex cables going to the panel. No replacement LCDs available anywhere, and you couldn't mount a standard 22" PC monitor LCD because of the T-CON being part of the mainboard..
Made to be thrown away..

Mine had a massive hackjob in the PSU. There were single diodes like in yours scattered all over the place in the PSU, but they each had another identical diode tacked in (soldered to their legs).
No idea if that was a desperate repair attempt from before I got it or if it came like that from the factory... either way..:

[budm]

Re: Sylvania LC320SS9 Flashing Green LED

Well Funai makes FUNAI, EMERSON, and SYLVANIA TV's. It bought the rights to use these AMERICAN name TV's brands a long time ago.
http://www.funai.us/brand/index.html
Schottky Didoe has low Vf and fast recovering time (tR) for switching power supply, regular diode will burn up fast.

[heavymachines]

Re: Sylvania LC320SS9 Flashing Green LED

hi all this i have same tv with same problem and yes its horrible design, however has anyone fixed this set? i am willing to give this one a shot if anyone is willing to try to troubleshoot this beast lol, thanks any help would be great. looks like this thread is dead but before i start new one i figured this thread is appropriate considering i have one with exact symptom not trying to hijack it but if i need to start a new one i will.... Thanks for any help or reply's..

[Th3_uN1Qu3]

Re: Sylvania LC320SS9 Flashing Green LED

You already have the location of the diodes, check them for shorts. If they're shorted, replace, and see if that fixes it.

[heavymachines]

Re: Sylvania LC320SS9 Flashing Green LED

not shorted tested out of circuit reads one way and not the other way when i switch the leads on dmm on diode test.... Thanks for your reply that was quick, well what to do next on this odd ball tv?.

[Mr Bill]

Re: Sylvania LC320SS9 Flashing Green LED

what is it doing? This tv the led was flashing for about 10 seconds then the tv went to standby. I had and emerson EM9 that the led would flash very fast continuously.

[heavymachines]

Re: Sylvania LC320SS9 Flashing Green LED

what is it doing? This tv the led was flashing for about 10 seconds then the tv went to standby. I had and emerson EM9 that the led would flash very fast continuously.

Same exact model symptom is almost identical, power led flashes rapidly for 10 seconds it will display digital television on bottom for a brief second then kicks to standby and just before standby i get 2 brief quick flashes....

[Mr Bill]

Re: Sylvania LC320SS9 Flashing Green LED

a bad inverter transformer on the power board can cause this symptom. Check the resistance readings at the ccfl plug with your multimeter in the OHMS setting. There was a thread within the last couple of days and a cracked solder joint was at fault too.

[heavymachines]

Re: Sylvania LC320SS9 Flashing Green LED

a bad inverter transformer on the power board can cause this symptom. Check the resistance readings at the ccfl plug with your multimeter in the OHMS setting. There was a thread within the last couple of days and a cracked solder joint was at fault too.

sorry i am lil green at this, however i am fully capable to learn, anyways where do i stick the probes and my dmm has lots of ohm settings, and where would i stick red and black probes so far i get no readings at 200ohm setting, Again thanks for helping me here.....

[Mr Bill]

Re: Sylvania LC320SS9 Flashing Green LED

You would put your red and black probes on the 2 pins at the connector. The reading is going to be higher than 2k ohms. I think it'll be in 9k range. Does your meter have a 20k range?

[Mr Bill]

Re: Sylvania LC320SS9 Flashing Green LED

I just checked my spare board and it's higher than 9k. Put your meter in the highest OHM setting it has.

[heavymachines]

Re: Sylvania LC320SS9 Flashing Green LED

You would put your red and black probes on the 2 pins at the connector. The reading is going to be higher than 2k ohms. I think it'll be in 9k range. Does your meter have a 20k range?

yes it does..

[heavymachines]

Re: Sylvania LC320SS9 Flashing Green LED

I just checked my spare board and it's higher than 9k. Put your meter in the highest OHM setting it has.

that would be 200 ohm highest setting. I am sure i did that, and it reads nothing but will double check in the morning when i go into work where the set is....

[heavymachines]

Re: Sylvania LC320SS9 Flashing Green LED

ok on 200 ohm setting its reads nothing i tried all ohm settings and can only get a reading if i set my dmm to 20m ohm and there it reads 5.3 m ohms at the bulb output connectors sorry took so long to reply got tied up with some things....computers and more computers anyways made some time...again thanks for you help, any ideas?

[Mr Bill]

Re: Sylvania LC320SS9 Flashing Green LED

Do all the transformers read 5.3 Mohm with your meter set to 20M?