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View Full Version : Failed battery diags! - help?



BSAKing
04-07-2003, 08:40 PM
I picked up a used TIVO but it has a problem. It is a sony Svr-2000 that apparently was operating ok

It goes through the initial bootup where I get the TIVO guy, then a grey screen that says almost there, and then - gives me a red screen that says

"Battery is either bad or missing!

DIAGS FAILED! "

I just replaced the internal battery and it is still doing the same thing. I also read about the battery holder and contacts being problematic, so I cleaned them really well as well with an emery board and contact cleaner and redid solder connections to be sure..
The battery feeds into a device labelled M41TS8 on it. Voltages and pinout look to be what I would expect to be on something like an eeprom of some type. I am getting battery voltage to that chip. It appears that one pin of M41TS8 feeds into a surface mount rectangle which has FSR327 on it. With 2 mounting tags at each end which are dead short between leg pairs on one end and wide open between pairs at the other. It is labelled Y5 on the board and is wide open end to end I am suspecting by the general shape it could be a crystal/resonator for the clock.

I did not get a match on either of these at Digikey. I just ran across the PS chematics and am going to check that out.
The hard disk does appear to be turning and it clicks when I unplug it, so power is there. The receiving light is on on the front of the unit. I am hoping perhaps it is a hard disk problem? If I were to remove it and hook it up to my PC maybe there is some sort of reset that I have to invoke or string to clear errors?

Any assistance appreciated.:p

BSAKing
04-08-2003, 09:01 AM
turns out m41T56 is a serial timekeeper clock with an external crystal, presumably for temp compensation/reference (not sure about that part). It could be the root of my problem.

I am going to scope mine out, but it doesn't look promising, or I may try replace it - it is an so-8 configuration. Now, to try find one somewhere!:confused:

BubbleLamp
04-08-2003, 10:56 AM
Not sure how close this resembles an SA Tivo, but in the rc.sysinit for a DTivo, you can comment out the section below to get around the battery check.



# see if we need to check the battery
if [ -f /var/log/battery-check-needed ] ; then
if [ -x /var/diag/batterycheck ] ; then
if /tvbin/crypto -vfs /var/diag/batterycheck.sig /var/diag/batterycheck /tvl
ib/misc/service-v3-s.pub ; then
/var/diag/batterycheck
else
echo "/var/diag/batterycheck failed signature check."
reboot
fi
elif [ -x /diag/batterycheck ] ; then
/diag/batterycheck
else
echo "Battery check not found!"
fi

BSAKing
04-08-2003, 11:29 AM
Great! That's approach number 2. I think the SRAM chip is amiss or the external crystal according to my scope. I am going to try fix the hardware poblem (wish I had schematics!), but if I can't, this will be next workaround on my list. I figured there would be something like that.

I have never been under the hood in one of these things until now. Ah yes - a newbie!

So - which file, which directory, which slice mounted under Linux may I find this in?

If I do get it all going, I will probably rewrite the disk after low level diags in any event to make sure it is all functioning properly for a long time.....

TIA, BSA.:p

BubbleLamp
04-08-2003, 11:52 AM
Originally posted by BSAKing
Great! That's approach number 2. I think the SRAM chip is amiss or the external crystal according to my scope. I am going to try fix the hardware poblem (wish I had schematics!), but if I can't, this will be next workaround on my list. I figured there would be something like that.

I have never been under the hood in one of these things until now. Ah yes - a newbie!

So - which file, which directory, which slice mounted under Linux may I find this in?

If I do get it all going, I will probably rewrite the disk after low level diags in any event to make sure it is all functioning properly for a long time.....

TIA, BSA.:p

The full path to the file is

/etc/rc.d/rc.sysinit

You can edit it by taking the hard drive out, hooking it to your PC, booting a Linux boot disk, and mounting the volume. The Hinsdale how-to would be a place to start to understand what that all means.

BSAKing
04-08-2003, 12:01 PM
Thanks for the boost. I'll check out those sources. (you have probably figured out I am not too worried about digging in...LOL).

LYK how she goes and will be back for more clues I am sure...

TTFN, BSA:p

BSAKing
04-11-2003, 11:17 AM
Well I put a scope on that chip and resonator combination and it is dead as a doornail. Voltages are ok, but that chip is supposed to drive the external resonator to produce a clock frequency and pulse to feed the rest of the circuitry so it knows the clock is there and active. So there is a hardware problem - surprise...

Good news is that those timekeeper chips and resonator (32.768 Khz) is a fairly standard clock/watch combination available from Mouser. So, I am going to order them and drop them on the board to see if that fixes the problem.

This weekend, I'll drop the drive into a pc and see if I can find a boot file with the clock checks in it to bypass that diagnostic until I get the H/W sorted out, and also modify it and whip up a cable to get the bash prompt on this beast.

Having fun..... imagine how much fun it will be if it actually works! LOL.

:D

BSAKing
04-19-2003, 10:25 PM
Well I got replacement components and repaced them on the board. Now I have an oscillator output. However, I still get the diags error and stopped boot. I will have to investigate further - maybe a voltage comparator circuit or something into the PowerPC chip? The RT clock should be there now. Or maybe a diagnostic file that did not get reset?

What I did do is go in and modify the boot file to bypass the clock/battery checks and now i get boot up waiting for me to dial in and subscribe. I can't do that from where I am, so now onto finding out what to do next. i am sitting there now with the bash prompt and menus :D

If anyone has some clues on where to look for info on how to proceed from here, please PM me.

TIA, BSA:p :p :p

BubbleLamp
04-19-2003, 11:14 PM
Originally posted by BSAKing
Well I got replacement components and repaced them on the board. Now I have an oscillator output. However, I still get the diags error and stopped boot. I will have to investigate further - maybe a voltage comparator circuit or something into the PowerPC chip? The RT clock should be there now. Or maybe a diagnostic file that did not get reset?

What I did do is go in and modify the boot file to bypass the clock/battery checks and now i get boot up waiting for me to dial in and subscribe. I can't do that from where I am, so now onto finding out what to do next. i am sitting there now with the bash prompt and menus :D

If anyone has some clues on where to look for info on how to proceed from here, please PM me.

TIA, BSA:p :p :p

You have a stand alone Tivo. They normally require a phone call to get guide data. Look in the Tivo Hacks section of this board, that's where most of the discussion about SA Tivo's takes place. I believe there is a way to create and import slice files for guide data. Otherwise, it's just a dumb digital recorder.

BSAKing
04-19-2003, 11:19 PM
Thanks - right now I would settle for a dumb digital recorder - can't get past the dial out. Have to snoop around a bit.

yesterday - nothing, today - a dial out menu, tomorrow - maybe a dumb recorder! Isn't technology wonderful! lol.

:p

BSAKing
04-22-2003, 09:03 PM
FWIW, I think my clock problem is now solved. I replaced the resonator and the timekeeper chip and get the proper oscillator waveform at about 22.7Khz.

Then what I did was modify the code to get into t he system. Then I checked and battery-check-needed variable had an occurrance in it.

I added in nullfiles to clear all logs, then took it out and rebooted. Now I have logfiles - like the tv ones,with stuff in them, but that variable is still clear.

I am a Linux newbie, but to me it looks like the code checks for the file variable, then checks to see what is happening in it. For some reason it was not clearing before.

FWIW, my tivo seems to be functioning now and I am getting into hacking it. Thanks for the pointers.:D