420 power problem

[skinerd]

That resistor near BFR sounds like the pull-resistor for BFR, check the resistance from the BFR pad to ground, it should br 10k ohms, if not more than likely there's your problem....the reciever will not boot if the resistance there is low..cause it will always boot to link.

[sfcmount]

If L10100 is getting too hot to touch you have a short on the 3.3V line. Guess what? The 3.3 volt line feeds power to most of the IC chips in the receiver. Sounds like a major problem to me. Even if you can find the IC that has the short it will be a real pain to change it. Also there is no supply for parts except from another receiver. It sounds like your buddy made you a new door stop. If it were me, I would look for a different receiver to mod.

[skinerd]

It is amazing that people, that have not a clue as to good soldering and electronic working technique, will attempt to mod a receiver. There is a warning at unwink, and other places, saying that if you can't afford to lose the receiver don't try the mod, so if it's gone, it's gone. I have seen people that are fairly good at this kind of stuff mess up a receiver. Pins on some chips are so close together that even the tiniest amount of stray solder will cause a short, and potentially ruin the IRD.
I have inadvertantly soldered where I should not have, by not paying close attention, but fortunately no harm was done.

[skinerd]

L14100 is a series choke in the 3.3v power supply.
BFR to ground should not be infinite.
If that 103 resisior is the one I see with a pad close to each end..then one pad should read short to ground and the other 10k ohms to ground..

[sfcmount]

Sorry for the confusion, I meant to type L14100 not L10100. As I said, you have a short on the 3.3V line which goes to hell and gone all over the board. I don't think you will ever find the shorted component, but you can use a strong light and magnifying glass and check to be sure there are no solder splashes on any IC pins or around the area that the original solder work was done. Have you checked the bottom of the board to be sure that none of the jtag pads are grounded by excess solder from the top?
Good luck,
sfcmount.

[skinerd]

The CPU chip has at least 18 pins that go to 3.3v source....check it closely for solder splashes......

[skinerd]

c14107 has about 160 Volts across it and could be leaky....
sounds like you are making progress..............

[sfcmount]

Glad it worked out for you. Your buddy should NOT be allowed near anything electric with a soldering iron. LOL.
sfcmount

[skq01]

Hi,

I have a similar situation, except the drd420re I did, belongs to my brother-in-law ... I'm using the "solderless technique" but have resistor wires soldered to BFR/ground (for boot to link mode) and VCC/ground (jtag power) to allow for alligator clips. I also accidentally burned the tape that goes from the front of the ird to the board (power, menu, info etc ..labelled .. S1 Item 1542003B). Note that even without BFR grounded (with my alligator clips), I can still boot into link mode.

Hope someone can help.......

[skinerd]

If it will boot to link without BFR grounded, the BFR is either accidentally grounded or the CPU chip is shot............check resistance BFR pad to ground, it should be about 10K ohms, if it's not there's your problem.......

[skq01]

[Thanks for the quick reply, Skinerd. You'll have to excuse my ignorance of electronics :( ... how do I "check resistance BFR pad to ground" ? I have a meter but don't know how to use it :(

Thanks again.

[skq01]

I think I got 10K ohms on my meter... Couldn't boot to link mode so soldered wire to bfr and grounded again (alligator clips). I was able to go in again (boot to link mode, read eeprom, erase, and reprogram with supplied file. Still can't power up. Is it possible that I damaged that ribbon cable/tape too badly (even though it looks OK) and is my problem ?

Thanks again for any replies.

[skinerd]

Does the remote work?? it does not use the ribbon cable connections.....

Does power light flash on when unit is plugged in??

You might have taken out something in the power supply, there are several voltages that come out of power supply, and not all have to be there for link mode, but the do for the unit to operate......

[skq01]

Thanks again Skinerd. No, remote is no good and power light doesn't flash on when unit is plugged in.
This is starting to be over my head :( How can I check the power supply ? Hopefully, there is still hope ...

THANKS again for the reply.

[skinerd]

There are a lot of posts covering the power problems in the 420's, do some reading and if you get stuck, shout.........

[skinerd]

If you can read schematics, and use a volt/ohm meter,a 420 pdf file is available......

[skq01]

Thanks again for replying. Unfortunately, schematics are a real puzzle to me (just looked at one for a 420) and a newbie with a volt/ohm meter. I'll keep trying though ... just need some tips :)

[skq01]

Well ... I gave in and took my receiver to dtvservice for more expert debugging (way above me now). I'll update when I get more. Re: my brother-in-law's drd420re that I screwed up; Anyone in Canada with one they're willing to sell ?