Another dead Phatbox ?

[liffy99]

Aaaghhh
For the 5th time I've had to remove the seats / panel in my TT to get to my recalcitrant Phatbox. Like many posts on the forum mine too seems to be playing a familiar tune;

All OK for weeks, then "NO CD" keeps coming up and generally staying until the car is re-started (but I can't replicate that every time). Today I'd had enough and decided to take another look. So I ripped it all out, took the Phatbox casing apart, removed motherboard etc. Checked all cable connesctions, cleaned connections with contact cleaner, checked connections at rear of Concert head unit, re-assembled and, voila, music !

For 15 seconds.

Then all went dead. Now pressing the Mode switch on the HU doesn't even register a Phatbox is there. No LEDs on the PB light at all and there is no noise from the hard disk. Concert HU radio works just fine. Fuses are all intact (unless I've missed one - was there ever a fuse for the CD changer in a TT ? I've checked fuses 37, 42 and the one on the HU).

So now the PB is lying forlorn in the garage. What can I do - is there anyone out there any more that can take a look at these things ? Anyone else had a similar problem and fixed it ?

Cheers

[sbingner]

Easiest thing is probably to look for a cheap phatbox on ebay...  that doesn't sound good...

If you're not sure about power you could connect power to the phatbox to see if it powers up and turns back off...

[liffy99]

How do I just connect power ?
Trying to access the pins on the HU / PB lead is just too fiddly (see below).

I did try putting a multimeter across the pins from the HU lead although I was guestimating which ones were power and ground from other diagrams (no Audi pinouts on this website) - promptly blew a fuse in the HU so I assume power is getting through.

[S80_UK]

I did try putting a multimeter across the pins from the HU lead although I was guestimating which ones were power and ground from other diagrams (no Audi pinouts on this website) - promptly blew a fuse in the HU so I assume power is getting through.

Not complete Audi pinouts - but you can maybe figure it out by combining data on these two sites...

http://www.phathack.com/index.cgi?page=pinouts

http://memebeam.org/toys/AudiHacking

Good luck.

[sbingner]

if you look at the MLB fron the front to the back, there is a place on the back left where there are empty solder-holes that power would connect to... if you plug it in you can test if it's getting power there with a miltimeter too, otherwise I can look for you and find what the pins were

[liffy99]

Tried using these pin outs when I started but they say slightly different things (GND is in different places for starters). I assumed pin 3 (GND) and 6 (+12v) frpm the VW/Audi CD cable. What does ACC mean ? Have I chosen the right ones ?

That said, trying tp out a multimeter across these tiny pins is not very easy, especially as I cannot get easy access to the cable itself. Also that will only tell me if power is getting to the end of the cable (which I presumed it was otherwise I wouldn't have shorted the fuse on my first attempt).

I presume Phatnoise don't have a repair agent in the UK. Is there anyone else that can fix them ?

I suppose the easy answer (assuming it IS the PB that is the problem) is to get a replacement unit from the US but that works out quite expensive with shipping, tax and exhorbitant Parelforce "release fees". I've also lost a lot of faith in the durability of the PB product - now wish I'd retained my CD changer.

Hmmmmmmm

[S80_UK]

Best place to check some of the signals is the 26-way connector on the Phatbox itself.  You need a steady hand though - the pins are quite close together. 

Just one thought - some people have found that even when the lock screws are tightened up, the connector can still move.  If so, this may be contributing to your problem.

You should be able to check these out...  For all Phatboxes GND goes to pins 4 and 16 and +12 goes to 10 and 13.   ACC goes to 14 on the 26-way, and is normally equivalent to the Accessory position on the ignition switch. So no volts there when fully off.  It goes typically to 12 volts when ignition or radio is on and it's purpose is to tell the PB to power up.  The PB takes next to no current from the ACC line - the current comes from the +12.

[sbingner]

This would be why I said to use the big power connectors on the back/left side of the motherboard

[S80_UK]

This would be why I said to use the big power connectors on the back/left side of the motherboard

Like this...

[liffy99]

Thanks Guys - but I'm a little out of my depth now.

If the PB is not connected, how can I measure voltage across the pins (same for using the MB locations) ? Presumably I connect to the 26 way from the head unit, then check across the MB locations as per the photo for power ? If I get a 12v reading then there is power getting into the PB and the problem lies downstream (in which case I presume its problems might surpass my investigative skills).

Can you give me a step by step guide ? i.e. Do I need to connect the PB to anything to test, or do I just place the multimeter probes across the appropriate pins ? Do I need to do all 4 (4,16,10 and 13) at he same time (the meter only has 2 probes) or is it just 4 and 10 for example ?

Sorry to be so dim - I've no problem in dismantling and cleaning stuff but I'm not into electronics. There are no loose connections as far as I can see.

Cheers

[sbingner]

I was saying you can just connect it to 12v using those pins... and see if it tries to boot up, that at least gives you an idea of if it's totally fried or not.  Otherwise, you can have it open... and connect the cable from the car and see if it has 12v on those pins...

Also, you need to make sure that the little button that gets pushed down when you insert the dms is working... it's shorting 2 pins of the 44-pin ribbon cable connecting the hard drive to the MLB... if the connector is lose, it will sometimes never see a DMS inserted and never power on

S80, thanks for the pic... I should have done that but I was too lazy

[liffy99]

Success at last !?! And thanks for all the help.
Had one last go at it yesterday and it now seems to be working. Odd thing is that when I re-connected the 26 pin connector the PB powered up ! So I re-checked all the connections again for firm contact - I even had it running with the 26 pin connector pulled half way out and it still worked, so it wasn't as if good contact was missing.

Anyway, I re-assembled the whole lot, carefully checking it was still working as I re-nstalled it into the car at each stage. One small modification I made was to glue a 4mm square piece of plastic (1.2mm thick, cut from a wasted CD) on the base of the DMS cartridge where it pushes the pin in on the MB. The aim was to ensure the pin gets pushed in firmly.

Whether this is what was a bit dodgy I don't lnow, but it's been working just fine for the past day.

Hmmmmmmmm