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cali
06-22-2003, 04:44 PM
Anyone work for a service center and have access?

I have my first dead tuner :D , the fun starts when I get a schamatic.

alldeadhomiez
06-26-2003, 03:48 PM
Originally posted by cali
Anyone work for a service center and have access?

I have my first dead tuner :D , the fun starts when I get a schamatic.

Any ideas on where to start without a schematic? My primary tuner is on the fritz right now. Maybe it has something to do with the fact that these damn chips run hot enough to fry eggs, yet the manufacturers did not see fit to install heatsinks.

And where do you find so many broken dtivos (or what do you do to them)?

cali
06-26-2003, 06:27 PM
I fix for people here and there, and in less than 6 months I have accumulated over 15 dead series 1 tuners, with one part fired on all of them :mad:

I have ideas where to start but a schematic would help me nail it in one shot.
If you look at the series 2, each tuner has an LNBP chip. ( in my case my LNBP is ok).

There are 2 smaller ones closer to the coax connecion, on each tuner. I haevnt pulled the data sheet on them yet. There is another slightly larger QUAD in the middle, of the two circuits, and I assume this is the equivalent of the DSPK demodulator on the series1 tuners.

If history has it correct, the problems from series one will carry over to series two, except they have made the cost of repairs much much cheaper, since the tuners are EMI separated, and the parts are out in "the open"

Push comes to shove, ill take it to work on the weekend and just swap parts to see which one is fuked up.
Over I like the design of the series 2, beter heat dissapation, better circuit layout overall. You can get real small heat sinks for the tuners, but the reason MOST tuners go out, is because people load them down with shitty connections.

I have never had my personal tivo tuner go bad. I bought this one (HDVR)on ebay, Error #51, fixed that , and now the tuner is shot.


Cali

PS. When u say on the fritz, how flaky is it?

Transponders going and coming?
Signal strentgh fluctuating?
One set of XPNDRS only?

alldeadhomiez
06-26-2003, 07:49 PM
Tuner 1 appears to be intermittent - it either gets stuck at zero signal or works normally. This might only happen when that area of the board gets hot but I haven't tried it often enough to tell.

Looking at the parts on this board it appears that we have:

CX24108-20 (http://www.conexant.com/products/entry.jsp?id=265) RF tuner IC, one per tuner

CX24130-12 (http://www.conexant.com/products/entry.jsp?id=753) dual demodulator IC ("ideal for PVRs!(tm)"), one per box

LNBS21 (http://www.st.com/stonline/books/pdf/docs/9096.pdf) LNB supply and control IC, one per tuner (this is the only link with an actual datasheet, the other two are fluff pieces)

plus a whole bunch of voltage regulators, crystals, and other components, one per tuner.

Since i can see 13v/18v externally while it is acting screwy, and since tuner 2 works fine, I think it may be safe to rule out the LNBS and CX24130? What's your take on swapping the CX24108's?

What are your symptoms?

cali
06-26-2003, 10:19 PM
You pretty much nailed it. :D
I took a quick glance at the info for the chips, and LNBP is out , and so is the CX24130.

In my case I get NO SIGNAL ON ANY XPNDRS. I will take a can of cold spray home tonight and see if heat is an issue.

I can get 13/18V also so I know the controller is at least communicating (CX24130)
They only other external factor could be dead xtal/pll.
Swapping is a viable and easy method of elimination providing you have tools.

The next problem is tracking down these chips, and due to special applications, I can almost guess it will be required to be purchased in huge quantities. Unless sony releases their Series2, and start carrying parts.

On a side note :
"Reed-Solomon FEC " IS THE SHIT!
I once worked on some highspeed optical stuff, and FEC still amazes me to date.

alldeadhomiez
06-29-2003, 02:16 PM
My unit has behaved fine since I started blowing cool air at the tuner area. Seems that when the tuners are not hot enough to scorch the mainboard they tend to behave themselves (so far).

I've been trying to figure out what kind of heatsink would fit these little bastards. Since they are like 7mm square nothing really comes in a small enough size. I was thinking of using "T-wing" material (http://www.flotherm.com/applications/app108/app108.jsp) (the stuff they use in the UTV) cut down to size. Any thoughts? Unfortunately this stuff seems pretty hard to come by in small quantities.

cali
06-30-2003, 01:17 AM
Lemme look around...we have lots o small heatsinks around ( work)

Also I did not go into work this weekend, neither next so I wont be able to swap tuners for a while on my unit.

Do they make thermocouples this small?:D

alldeadhomiez
06-30-2003, 11:46 AM
Originally posted by cali
Do they make thermocouples this small?:D

That seems to be a bit of a sticking point. It's not hard to find slightly larger ones for video cards but it seems pretty uncommon for chips this size to run as hot as these things do (and thus nobody sells heatsinks for them).

IIRC double sided thermal tape was fairly costly at digikey. If you find a good, cheap source of suitable thermal materials let me know.

BTW what is your theory on how bad cabling causes the tuners to go bad? Or were you referring to the LNBPs?

cali
07-06-2003, 09:51 PM
I've located a few heatsinks, but they overlap a bit.
I have yet to try them out, as I droped my powersupply and I have to patch up the PCB :(
If it works out, I should be able to get a few for you and a couple others who may want them.

Cali

cali
07-06-2003, 09:54 PM
Originally posted by alldeadhomiez

BTW what is your theory on how bad cabling causes the tuners to go bad? Or were you referring to the LNBPs?

On the tuners going bad.....well I think is a direct relation to the LNBP going bad.
The LNBP if overloaded IS SUPPOSED to shut down,but for some reason it doesnt fast enough I think poor grounding, lightning, shorted coax, and RCA multiswitches, are all major contributers.
IN all boards where the tuner died, the LNBP was cooked bad.

alldeadhomiez
07-07-2003, 08:04 PM
Originally posted by cali
On the tuners going bad.....well I think is a direct relation to the LNBP going bad.
The LNBP if overloaded IS SUPPOSED to shut down,but for some reason it doesnt fast enough I think poor grounding, lightning, shorted coax, and RCA multiswitches, are all major contributers.
IN all boards where the tuner died, the LNBP was cooked bad.

Interesting. I presume you are mostly talking about S1 tuners?

I transplanted my suspect HDVR2 tuner chip into a different unit a few days back, and the problem did indeed follow the suspect chip. Now I suppose the next step is to figure out whether my soldering job was obvious enough to void the warranty.. heh

cali
07-08-2003, 07:01 PM
Oh yeah def series 1 tuners.

You gonna send it in for warranty work?

TO be totally invisible, to tampering, I suggest buring that area beyond recognition, that way youre guranteed a new unit.

How did you swap? U have access to hot air pencil,etc?