Yet another headunit won't recognize PB thread

[LloydDobler]

Hi guys, I have a real stumper here and it's pissing me off, but there's still a lot of things I can try.

I have a VW phatbox reflashed to Keg firmware and hacked.  It's worked fine since June or July whenever I installed it.  It has a homemade cable and is connected to a Kenwood KDC-X890 head unit. I installed a new amp this week and removed the head unit, and jiggled the cable around a bit, and when I buttoned everything back up the head unit wouldn't recognize the phatbox.  I can't select it in the source menu.

If I unplug it and plug it back in, it goes through the power up cycle, both LED's do their thing, and then it shuts down.  I can audibly hear the hdd spin up and down and everything.

I've tried it in all possible combinations, power on, power off, radio mode, standby mode, etc.  

If I unplug it and plug it back in without the cartridge, it gets recognized as a CD changer.  If I put the cartridge in with the system turned off, it powers up and then is gone.  I haven't tried inserting the cartridge with the power on in the cd changer mode.

I've tried the cartridge in my other car that has a Keg in it and it works fine.

Will re-flashing the firmware usually force it to talk to the head unit again?  What flags do I set in the config to just re-flash?  Or is it just one flag?   I re-flashed the firmware, didn't work.

My next step is to go through the hassle of taking the whole phatbox out and trying it in my other car.  I suppose then I could string the cable across and try the genuine Keg on the head unit that doesn't work, if that also doesn't get recognized I suppose I need to assume my cable is busted or my head unit is messed up.  

Oh, one other thing:  I broke the solder joint where I had the cable shield attached to the connector shell on the PB end.  Would not having the shield grounded to the phatbox cause this problem?  I did test the phatbox for ground and the aluminum case is still grounded to the head unit, so I assume the cable's ground wire is still working.

Edit:  I've also tried completely resetting the stereo, unplugging it from all power, doing everything in all the correct order.

Another possibility is that I'm running an older firmware (12.05) that is missing some important flag for this brand new stereo.  

Anyway, any ideas are appreciated.  I'm really stumped here.

[LloydDobler]

Never mind, I pulled the whole PB out and it doesn't work in the other car either.  Somehow bumping/tugging on the cable fried something inside.  It still powers up and all that but either head unit won't recognize it even after a firmware flash.

I opened it up and no components look burnt or anything, but something stinks like it melted down.  Crap.

[Evilution]

If it's hacked, try another HDD before skipping it all.

If you do skip it, remember that I need a USB cradle  

[markbowen]

Sorry if I am suggesting something obvious, but Kenwood HUs almost always have to be reset before they will recognize the phatbox.  I did not read that you tried that, so if you did not, that might sort it.  Most Kenwoods have a little reset button somewhere on the faceplate.

[SteveC]

I would also check to make sure you are feeding it enough power. Adding a big amp (you don't give any specifics) can change the "balance of power", and the Phatbox may be starving.

Unfortunately, the fact that it doesn't work in the other car makes me think that something got fried during the installation, or that the cable may be tweaked.

[LloydDobler]

Yeah, the fact that I could unplug the Keg from my other car, plug the phatbox in (to the factory Keg cable), that head unit doesn't recognize it, then plug the Keg back in and it works, says to me that the phatbox itself is fried.  All I did was pull on the cable a bit, but the connector looks fine.  The fact that it still powers up and spins up the hard drive is what really stumps me.  Everything appears to work fine except no recognition.

I might try the reset button, but I didn't think that was any different than removing power completely, which I did.  I pulled all 3 audio fuses from my fuse panel which did lose all my radio presets and bass/treble settings and all that.  Besides that, I've never had an issue with Kenwood stereos recognizing the Keg or PB before, and this is the third one I've installed (a friend has one).  The first time I installed this unit I had been using the HU for a month and I just plugged it in and it was recognized from the get-go.

And no it's not a power starving issue, I ran the amp power straight from the battery.  The head unit and phatbox wiring are untouched from before.  The only reason I pulled the head unit at all was to run RCA cables for the new amps, which is how I was tugging on the cable.  What really scares me is if I messed up the cable by breaking something internally, is any PB I install going to fry instantly?  I should probably pull it out and trace all the wires to make sure none are crossed.

Also, I'm not selling anything because I bought this phatbox barebones on Ebay ($30), and only have one complete kit with cradle.  In fact, I was only using one cartridge between the two cars and it still works fine in the other car.

[sbingner]

You might try putting the forceupdate files on... and see if it re-flashes your CPLD firmware.   I've had them 'hang' before and need to be reflashed when I was messing with my phatbox, but I was doing really stupid stuff then.   Like trying to figure out how to emulate the 51d program...  and getting 2 copies running at once by mistake.

[LloydDobler]

Would it fix this?!?



So yeah, tugging on the cable obviously crossed a connection or two.  I'm gonna do a full trace on the cable and make sure nothing is actually broken/shorted in it, but basically at one point my cable dropped on the floor and I set my drill on it, tugging pretty hard.  I've let the precious smoke out of something there.

[S80_UK]

Nice picture...  

Something to think about - the parts that have visibly been damaged are diodes wich are there to protect the signal lines to and from the head unit.   Now, it depends exactly what happened.  If they did their job, they will have prevented damage elsewhere.  If not, other parts could have been fried as well (including the 8051 micro - some of the signal lines from the HU go straight into it).

What I would do...
  1) thoroughly investigate the HU wiring for shorts.  Also look for possible broken wires - a broken power or ground wire could also do bad things.
  2) consider getting another box - (no need for DMS etc, obviously).  I would not borrow one, in case I fried that too.
  3) if the new box works, then breath a sigh of relief that the HU is still OK - if not, drink beer...
  4) Depending on the above and your willingness to hack hardware, look at replacing the burnt diodes.  I seem to remember that they are 5.1 volt zener diodes - but can't be 100% certain.  The others (D8, D5, D7 etc) are of the same type and have the same job clamping signals, so that may help.  No guarantees here - I would only go down this road if desparate.

Good luck!

[zero cool]

AHHH, i want your broken PCB board! I just happen to have a PCB board from another phatbox i need to test. if it works we can work out a swap, if it doesnt i can fix one or the other and we can work something out.

 I am always looking to buy dead P.B.'s or parts


Zc

[zero cool]

D12, D13 are labeled CX3 and they are diodes from signal lines to ground. These may or may not have protected other parts. as these are designed to catch small spikes to ground not a full 12V or something where it is not supposed to be!

Zc

[LloydDobler]

Nice picture...  

Something to think about - the parts that have visibly been damaged are diodes wich are there to protect the signal lines to and from the head unit.   Now, it depends exactly what happened.  If they did their job, they will have prevented damage elsewhere.  If not, other parts could have been fried as well (including the 8051 micro - some of the signal lines from the HU go straight into it).

What I would do...
  1) thoroughly investigate the HU wiring for shorts.  Also look for possible broken wires - a broken power or ground wire could also do bad things.
  2) consider getting another box - (no need for DMS etc, obviously).  I would not borrow one, in case I fried that too.
  3) if the new box works, then breath a sigh of relief that the HU is still OK - if not, drink beer...
  4) Depending on the above and your willingness to hack hardware, look at replacing the burnt diodes.  I seem to remember that they are 5.1 volt zener diodes - but can't be 100% certain.  The others (D8, D5, D7 etc) are of the same type and have the same job clamping signals, so that may help.  No guarantees here - I would only go down this road if desparate.

Good luck!

Yeah the first thing I'm going to do is thoroughly trace out the cable.  I did break the ground wire that connects the backshell to the cable shield, but I think that's a redundant ground for shielding purposes.  The fact that it powers up and can be recognized as a CD changer with the cartridge out really gives me hope that it's not destroyed, and that I've just broken a circuit needed by some of the controls.

Once that is checked out, I can just string the cable over to my working Keg that is in my other car.  If that works, I'll talk to a friend of mine about repairing it.  The guy is an EE and should be able to determine exactly what I need to repair it, and he'll have access to the parts and tiny soldering irons etc.  If that fails, I'll just buy another PB off ebay or something.  

If I blow the other Keg though, I'm just going to admit defeat and buy an iPod or a knockoff and use the aux in from now on.

I'll let you know if I can't fix it and want to get rid of it Zc.

[S80_UK]

D12, D13 are labeled CX3 and they are diodes from signal lines to ground. These may or may not have protected other parts. as these are designed to catch small spikes to ground not a full 12V or something where it is not supposed to be!

Zc

Agreed.  But many of them have resistors between the diodes and the signal line, so that the diode clamps the voltage into the PB board hardware and the diode should not normally get zapped (see RP11, RP12, and RP13 on the board).  But I know that when I was hacking around about a year ago, the ones that fried here are not so protected - I think they go straight to the external connector.  Hence my concern that either some other circuitry may have suffered (they go to a 74ABT125 chip I think - my notes say AB125).   LloydDobler - that's a small 14 pin chip somewhere - your friend may be able to locate it and possibly replace it if necessary.

One other point - the CX3 marking is probably not a true part number.  It will be the makers code number which translates back to a part number.  Many surface mount parts are labelled with a short code simply so that it is easy to read.

Let us know how you get on.

[LloydDobler]

HELL YEAH.  

My buddy was able to determine exactly what the part was (6.8V zener diode) and he didn't have the identical part, but he had the same part in a through hole design that he was able to cobble up to fit, and so he took it to his office and soldered it up for me.



And it WORKS!  No other components appear to have been damaged in any way.  Sorry zero cool, no parts for you!

[S80_UK]

Fantastic!!!        

Glad you're back on the road.

[Evilution]

Sweet, that is exactly what I would have done.