[MTCD Android Head Units General] marchnz:
QUOTE="typos1, post: 89479482, member: 456516"

Hey man thanks for your reply.

Cant believe the RAM upgrade we did was 9 years ago !!

** Way too fast.

It's deffo nothing to do with the panels display driver because the panels I'm trying all work on another unit so it must be something on the mobos, there is a video controller listed in the schematic maybe it's that? I think I actually may have caused the problem myself a few years back when I was trying to repair a friends unit - I mistakenly thought that the ribbon connectors could not be connected incorrectly but there are pins on the upper part and the lower part so they can and pretty sure I connected the cables upside down which caused the issue. I tried every panel I had on the 3 boards before realising 🙄. Haven't tried mcu settings as these panels came off these units.

** OK, got it. May have shorted +5v supply to tft. Check +5v, pins vary between Wilson and generic schematic - pin 3,4,5,6 (check if grnd on pin 50, the opp end, then use this) or listed as 34,35,36 +5v (you should have ground on 47, 46 and 6.) Difference looks to be a 57pjn connector on one and 50 the other, if that makes it easier to ID.

Also check U16 FMS6502, video processor, especially +5 pin 20.

With the unit that shuts down after a bit I noticed that there was some dry solder on some of the mcu pins so I cleaned it up and added some more solder over the top (they had continuity but just did it to make sure). I got some improvement, it booted up for a bit longer and would power on again sooner but don't really know if this is the problem or not and don't even know if my idea about the rgb controller would actually be the problem either.

I took your advice about the crowbar and it was giving out low values. So I swapped it for one from a damaged board which was a real pain -

** I should have mentioned- just remove it altogether for testing.

worked ! The board powers up ! .....but the screen is black, at least I get some sort of response from the other screens 😪.

I don't have a solder sucker and I have done some spot repairs to some chips before - which is a pain cos of the size - but I didn't fancy soldering 21 tiny pins. So I bought that amp/dsp box for £22 and spent hours making 2 new looms, but guess what - using the RCA outs I get the same problem - loads of distortion and low volume, it sounds like the amp chip has blown even tho it's being bypassed!

** check ic listed as u7 BD3702, audio processor. Check +9v on pin 24, fed via an inductor fb7 that might be open circuit.

If it's not that, then suspect the bd3702 is bad.

I got this unit years back before I bought a car which I didn't buy in the end. So I sold it to a friend and fitted it for him, we listened to it for 20 mins or so and then it started to distort badly, it was unlistenable. So I gave him his money back. When I opened the unit there was a 5mm gap between the back of the unit and the chip so it wasn't dissipating heat. I adjusted it so It was touching the back of the unit, added some more heat paste and tested it on the bench with one speaker attaching it to each wire and playing audio for over an hour, it was fine no distortion. It sat in a box for a few years then I sold it to another friend but as soon as it was connected it distorted so I figured the amp chip was fried. I thought about using the RCAs with an amp but remembered after reading the data sheet years ago that the amp also has RCA pins on it so wondered if that would work, but a quick search on here came up with someone who had a fried amp chip and used the RCAs so I thought it would be ok. This guy also removed the amp chip altogether and it worked ok so wondering if I should do that or whether it's something else entirely like the wolfson audio chip ? And if I remove the amp chip would I need to bend the pins that control the RCAs so they touch?

** if the audio output ic has failed (it should have been firmly against the rear panel/heatsink, it should be removed. Unlikely it is affecting rca, but worth a try. No pin bending required.

What a load of hassle nothing's ever easy.

** but fun all the same.

/QUOTE