PDA

View Full Version : Has anyone every successfully fixed a bad tuner on their unit?



sfg
01-10-2004, 05:15 PM
Tuner 1 finally went completely on me and I am looking for someone who has fixed this problem (hopefully someone out there has).

sfg

GREEK
01-10-2004, 08:07 PM
I do em every day........the hitch is finding the part, doesnt exist anymore......

sfg
01-11-2004, 12:20 AM
I assume it is usually the same part that goes.

sfg

GREEK
01-11-2004, 07:35 PM
Do you have signal on any transponders, you must check all on 101A on BOTH tuners. Report back what you have if any. You may have a pattern of only the first few, odds or evens. Check #2 to see if it has signal issues also. You may have low 30 volt line, bad lnbp chip, or bad tuner. The QSPK chips goes in the tuner often, but theres 2 caps that sometimes go too. I jsut replace the whole tuner mostly...........

sfg
01-12-2004, 03:02 AM
No signal at all on tuner 1. Tuner 2 is fine.

I used my IR temp gun to check for temp in various parts of the tuners and found that the 2 caps (I believe thats what they are) in tuner 2 are running at least 20 deg c hotter than the ones in tuner 1. Maybe it means something maybe it doesn't.

I am going to go through the tuners again and check for voltage at the lnbp's.

I will let you know what I found out and see what you think.

Thanks for the help
sfg

GREEK
01-13-2004, 07:10 PM
just use the voltmeter and find the trace for the middle leg of the lnbp chip. DONT test right at the chips legs, shorting out 2+3 will fry your machine. Go out a bit and find the tiny hole the trace passes through to the underside of the mchine, there will be a TINY little copper ring there, test there. pins 1 and 2 should have 24v, and 3 should have 13 and 18, for evens and odds. If you switch the xponder to an even then odd the voltage should go 13 and 18. If it does 99% your chip is good, and tuner is shot. You can easily pop the cover off the tuner on the fin side and look at the large chip in the rear. It may have slight damage, and also the lower frontmost red colored capacitor goes often too.....

sfg
01-13-2004, 11:24 PM
Thanks Greek

I will do it tonight and post my results.

sfg

sfg
01-14-2004, 12:27 AM
but I can not find a cover over any tuner nor a red capacitor

sfg
01-14-2004, 12:52 AM
I don't know why but it's working. I couldn't get to the screen for testing signal strength, it would just hang on please wait so I rebooted and now it works.

After numerous reboots and signal strength testing it works.

Now all I have to do is get it back in place with it wired up and see if it still works.

sfg

sfg
01-14-2004, 01:14 PM
guide data would start to download and then the tuner would go out again. I verified this by checking for signal on tuner 1.

I will check the points you mentioned but I still don't recognize your description of the tuner. Where on the board is it located?

The only thing on my board with any sort of cover on it is the rf in/out.

sfg

GREEK
01-14-2004, 11:51 PM
you have some sort of cold solder or a half contact. I am talking about the ACTUAL tuner module, you can clearly see covers on the left and right sides. The left side has a slit that touches the large main chip on the left side of the tuner. Grab a straight blade screwdriver and pop it off, you cant break it. You now have the guts exposed and the large rear chip the slit sits on is the major bad part, and the front below the coaxial cable connect is the red cap. You wont find anything if its working though. I would grab a voltometer and the schematics off the board and start tapping the tuner and frame til it stops working and test outputs. Either your lnbp chip or tuner has a bad contact or is broken on one of the pins........

sfg
01-15-2004, 12:59 AM
I swear there is no cover. The tuner modules are open with no cover over them. I have located the tuner IC cx24108-20 and the LNBP's as well as cx24130-12 which I have found referred to as a dual demodulator. Are we talking about the HDVR2 here?



you have some sort of cold solder or a half contact. I am talking about the ACTUAL tuner module, you can clearly see covers on the left and right sides. The left side has a slit that touches the large main chip on the left side of the tuner. Grab a straight blade screwdriver and pop it off, you cant break it. You now have the guts exposed and the large rear chip the slit sits on is the major bad part, and the front below the coaxial cable connect is the red cap. You wont find anything if its working though. I would grab a voltometer and the schematics off the board and start tapping the tuner and frame til it stops working and test outputs. Either your lnbp chip or tuner has a bad contact or is broken on one of the pins........

nostalgia
01-15-2004, 02:07 AM
Tuner 2 only recieving even transponder.

Just took some measurement on my LNBP chip for tuner 2. I'm getting a constant 18V when i switch between and and even transponder. LNBP chip for tuner 1 is changing between 13 and 18V? Does this mean I need a new LNBP chip?

sfg
01-15-2004, 02:32 AM
So for I have found that the tuner sections are all ok by virtue of comparing voltages between tuner 1 and tuner 2. The only difference is at r2008 (.847v tuner 1 compared to r2017 (2.67v tuner 2).

According to the data sheet for the lnbp (comparing the two lnbp's)

Tuner 1 Tuner 2
pin 3 LT2 7.3mv 9.8v
pin 7 ADDR .3v 3.3v
pin 15 DSQout 1.1v .82v (I want to verify pin 15's #'s again though)

This is what I have found so far. I can't find anything else at the moment 'cause the damn thing is working again.


Thanks again for the help Greek
sfg

GREEK
01-15-2004, 02:45 AM
You should have said so. Didnt you post you had a T60 in the other thread? ANyway by the #s on the ICs posted you have a ser2 machine, probably an HDVR2? Look carefully at the #s you reported and you can see the problem. ANY IC has a range of power it uses. You have way too much variable going on there. .8something compared to 2.67something is way too much. Its late now, but I'll grab the schematics and give you the actual voltages supposed to be there. There are known problems with certain runs of these, mainly losing signal on odds or evens. If your losing signal al together you have a bigger problem. I have had units in the run and a new chip solved it, the problems followed the chip into a known working test unit. WHats the make date on the back of the unit.

Nostalgia...you have a bad lnbp chip. check your thread

sfg
01-15-2004, 10:46 AM
Sorry, I had originally posted this in the series 2 forum but it got moved.

When you say "a new chip" are you referring to the dual demodulator chip?

sfg

GREEK
01-16-2004, 12:51 AM
I'm talking about the lnbp chip, theres 2 that say lnbp20 something on them. This is for odd or even problems, if you have no signal, I would say you have a cabling problem, not a tuner issue. I have only seen 1 tuner issue on all the ser2 that have come through here, but LOTS of lnbp issues, they had an official bad run of chips. WHen it goes out on the signal screen flip to the next transponder and see if you have even or odds or nothing. I would first swap sat feeds to see if the problem follows the cable or is in fact the tuner on the tivo........

sfg
01-16-2004, 03:42 AM
I have verified that the cable is working properly by switching over to tuner 2,works fine. I have tried three different cables all work with tuner 2 but not with tuner 1 when it decides not to work.

When tuner 1 goes out I lose all signal(this happens only on reboot). Its seems that when I leave the unit unplugged overnight it will work the next day on first boot but if I reboot it will not get a signal.

I suspected it may be a heat issue so I have left the cover off and even tried cooling the the chips with "cold air in a can" with no affect.

I have noticed on boot the r2008 and r2017 are at .865v during the boot process and then they flip to 2.67v at some point during the boot process when both work(both of these resistors are traced directly to the dual demod chip). If tuner 1 isn't going to work r2008 stays at .865v. Once this resistor has its 2.67v it does not lose it. In other words if the tivo boots with both tuners working then they stay working until the next reboot.

I maybe wrong in saying "tuner 1" isn't working. Maybe I should say no signal at tuner 1. The tuner may very well work as I stated before everything encased in the gold trace is equal between the two tuners except for the two resistors stated above.

Both LNBP's flip from 13 to 18 regardless of signal at tuner 1

pin 7 (address) of LNBP for tuner 1 always has .3v which does not correspond with LNBP for tuner 2 which has 3.3v.

I have spent 3 hours rechecking all this info and now the damn thing hangs on "almost there". I hope I didn't cross some pins with my test probes!!!!

I wish I had the data sheet for the dual demodulator chip!! Well I guess this has gone on long enough.

sfg

sfg
01-18-2004, 12:20 AM
Read the above post and let me know what you think.

sfg