fta Sat TV decoder: Need some ID

[bushtech]

To try and check must I trace the line from the centre (+) of the power supply connection?

 

[the great potato]

funny story ... yeah about 1 day ago i was playing a game and all of a sudden my Sat box started turning on and flashing ON over n over, unpluged it ..now it dont turn on !! LOL Yeah, i got to open it up and check it out, have a feeling its just a cap. But i really cant complain it was 30 bucks and lasted 2 years with no probs.

 

[Externet]

3 of the caps show no voltage across them, I am picking up replacements tomorrow for all the caps. Hope that sorts it

Is the unit in standby mode waiting for a remote control signal to turn on the rest of the power supply ?

Replacing capacitors by guessing will fix nothing.

FTA with a card slot ? What for ?

 

[bushtech]

@ the great potato: If you decide to fix it please post a photo of your pcb here. Would like to compare it to mine. And if you buy a new one please drop a link here, I might still end up in the same boat.

@Externet: Don't think so, it switches on straight to the 2 red leds flashing. I managed to get hold of a tech who has fixed these at the supplier. He reckoned replacing caps and diodes has a good chance of getting it running again.
FTA with a card slot. Heh. This is South Africa- weird things happen here. Here's a link to the fta service: http://www.openviewhd.co.za/products

 

[Externet]

I would say it does not switch on to the two red leds flashing. Cannot switch on, and the flashing leds are fault indicators warning you it did not turn on.

 

[bushtech]

Ah! This might help. Powered it on again and it went to one red led burning which is correct as there is no link to sat dish. But if I keep it powered on I expect it to bomb out again in about half an hour as it did the previous time. But this might be a clue as something is resetting itself after a rest/cooldown?
The heatsink does get hot very quickly, within seconds of powering up.

 

[Externet]

Let it off a good while and turn on with a cotton ball soaked in acetone/alcohol on top of components that heat up.
If runs longer, a component thermal failure is to suspect, or overvoltage causing such. What is the voltage reading on the power rails, and how clean/spikesfree is the power when on ?

 

[bushtech]

The only component that I have felt hot so far is the heatsink. Just had another feel around and the only thing I can feel hot is that heatsink getting hotter and hotter. I am still a rookie at electronics so if you can give me some pointers as to where I can read the voltage on the power rails I would really appreciate it. When you talk about clean/spikefree are you talking about the mains power?

 

[Externet]

Voltages across all the electrolytic capacitors, included the suspect ones in line to replace. Should be like 2.5, 3.3, 5.1, 12 V...
The spikes/ purity of the supply can be seen with an oscilloscope. You want minimum ripple.

My FTA receiver below decided one day to quit, by rebooting endlessly. Warranty replaced, left the failed one behind the spider webs a while and when re-tested, has worked flawlessly for 2 years now. Mysteries... ¿?

----> http://www.x2sat.com/premium-mini.html

 

[bushtech]

Thanks Externet

Will check those voltages. Don't have a scope so can't check spikes/ripple.

Sigh. Looks like keeping it running for a while last night bombed it out again. Fired it up again this morning and it went straight to 2 flashing red leds

 

[bushtech]

"Measuring the two inductors:
PH01: 8.1Ω
PH02: 5.8Ω"

Nowhere near 0Ω 73's de Edd, does this mean they are bad?

 

[73's de Edd]

No problems on the inductors . . . .as they are inducting.
Now to your worrisome HOT u/p heatsink . Have the unit in a cold temperature state, with no latent heat on the semi s, particularly the u / p heatsink.
Build your self a double thickness aluminum foil boat that is leakproof ! to rest on top of the he heatsink and put a large . . . .or custom casted . . . Ice cube inside to cool down the heat sink for a trial power up to see if turn on and then some possible run time occurs differently.

 

[bushtech]

Would love to try it but it will only happen if I can get it to fire up. When I plug in power now I get two flashing red led's. It did recover once before so here's hoping

 

[bushtech]

Got it so it's running with one red light again. I now want to put it in a cryogenic state with a dry ice block on the heatsink. But while it's running like this I want to check the voltages of all 14 electrolytic caps.
How do I do this? Do I put the neg probe of the dmm on the neg side of incoming power?

 

[davenn]

Got it so it's running with one red light again. I now want to put it in a cryogenic state with a dry ice block on the heatsink. But while it's running like this I want to check the voltages of all 14 electrolytic caps.
How do I do this? Do I put the neg probe of the dmm on the neg side of incoming power?

put the probes across the electros .. + on + , - on -

 

[bushtech]

Thanks a mil Dave. Now I can start checking

 

[bushtech]

With the set switched on (one red led burning) and in a semi cryogenic state with a dry ice block strapped to the heatsink:
Caps:
CEP01: 220μf 16V = 5V
CEP16: 470μf 16V = 12V
CEV02: 220μf 16V = 0V
CA14: 220μf 16V = 0V
CEV01: 220μf 16V = 5V
CE103: 220μf 16V = 5V
CEP05: 220μf 16V = 3.3V
CE01: 220μf 16V = 5V
CEP03: 220μf 16V = 3.3V
CEP02: 470μf 16V = 0.97V
CE03: 220μf 16V = 5.1V
CE752: 100μf 50V = 19.4V
CEP04: 220μf 16V = 0.95V
CE751: 100μf 50V = 12V

Do I now start investigating the 2 caps with 0V on them or where do I go from here?

 

[bushtech]

Can anybody help me?