Alpine CD-9831 shuts off randomly

[sergei]

Howdy,
I have this CD-9831 that is gathering dust because of a really intermittent and annoying problem:
It works fine until it decides to shutdown completely time period from minutes to hours. Only way to temporarily resurrect it is to unplug it from the power and plug it back in.
The reset button does nothing.

I am trying to figure out what kind of power supply this unit has (linear regulator vs switchmode/buck converter).

I have spotted when it shuts down it looks like PSU cuts off and not software shutdown as all the lights are going down as capacitors discharge.

I am not familiar with head unit inner workings and I hope there is schematic diagram floating around (yeah right).

Has anyone had similar problems?

I took it out to an alpine authorised repairmen, a year ago, and they tried it and bugger refused to shut down all time they had there, so they charged me $80 and send me home blaming my installation.


BTW it is not connection or my 12V problem, it does this in the car and on the bench.

Alpine is also in denial that NZ exists, and I had a drift from repairmen that because it is parallel imported Alpine is very reluctant to have a look at it. I say bite my shiny ass. If it is made by Alpine, Alpine should honour the paid service on units. Here I am ranting again.

I am happy to pay another $80 to $100 to get it fixed even if it is 5 yo unit.

[sergei]

I managed to find schematic (really surprising).
Now on to figuring out how that thing works....
While trouble shooting I figured the whole +5V line that powers the face plate among other things, drops when this happens.
While 3.3V, VDD(+5V) and various +12V lines are live when it powers off...

[sergei]

So here I am stuck at L5952, which takes digital signal in as control, and I have no idea what uC sends to it...

[snwtoy]

you scare me.

[soven]

Try Soundwave services in Auckland.

[sergei]

Ok, who whom is interested, I traced that there is no clock or data going to L5952 (which is just a digitally controlled multichannel voltage reg, fancy one that is), the data is actually I2C.
The clock is generated by CPU and it has separate crystal for this purpose 32.something kHz), I have noticed during malfunction the crystal had weak or no waveform, while during normal function I could see the square wave clock and data coming out of CPU.
I had to pull out my good old trusty oscilloscope for this...

So I have to figure out if the crystal is the cause or CPU....

[sergei]

It looks like it is crystal, could not find equivalent at home today to test that theory, but I managed to restart it every time when it died by creating loose connection (by soldering it only one leg, another just touching).
I never encountered crystal failures.

Although it could be a dry joint of some sort.

I have tried to warm it up to see if it was the heating up that caused this.

I have read that crystals can fail if they are over driven...

[sergei]

Argh, I give up... This thing works without that crystal (and dies after random time period), so back to square 1...

[mr30%jr]

you are rather scary... i have a kenwood which does the same works for about an hour and then dies. but you can reset it.

someone removed the eprom with that contains the security code... you can do some crazy test mode it which you can dump the eprom to the main processor and vice versa but it fails

just an idea.. man serg u sound pretty clever

[sergei]

I have feeling that CPU goes into some fail safe mode, I still have to catch what it actually send to I2C just before death. But I don't have the necessary equipment (I only have analogue 40MHz scope). Need some digital scope with recording abilities, but this goes beyond the cost and time.
It also looks like Alpine basically using same CPU on almost every model as I dug through a few diagrams and they all were very similar.
There was nothing in repair manual on how to set it in test mode (if it has).
Also there was nothing what voltages/waveforms should be on many multiple test points. I wish you could just jump couple of pins to put it in diagnostic mode, just like some equipment.
But they make those things throw away items, this way they can sell more units. So there is no interest in repairing them unless they are under warranty.

[Alex B]

Had a look on ebay etc for a replacement main board, my guess is that Alpine got their hands on it that would be what they were quoting.

[sergei]

Here is what looks like my solution to the problem:
http://www.parallelimported.co.nz/car-a ... -deck.html

Counting in $50 p/h of my time I will have to spend in addition to what I have already spend (although it was fun) replacing mainboard is not as much rewarding and counting the price of such mainboard (will not be $50) I say I get new unit.
As bonus it supports usb drives (well it claims so, I will have to do research on this).