PM2 battery leakage

[dg211]

Hi, hoping someone can help me with my PM2.

The batteries leaked in it in a manner very similar to this

http://www.c2forum.com/viewtopic.php?f=10&t=11589

which judging by other posts on the forum is a very common problem. Following the advice elsewhere on the forum, I very carefully removed the battery gunk with vinegar, then cleaned off the vinegar and carefully dried the board. Several copper traces on the board were discoloured and the gunk had been all over a couple of capacitors and an IC, so I was convinced the board was knackered, but when I replaced the batteries and after a four finger reset it gave every indication of working normally. Then I removed the batteries again overnight, and when I tried it this morning a few random segments lit up on the LCD and then it went dead. Can anyone suggest what the problem might be now? If I left some trace of acid on the board, could that have damaged the components? Alternatively, can anyone suggest a good place to look for a relatively inexpensive replacement?

Any help would be greatly appreciated.

[Carl Watts]

Some of the tracks will probably be corroded right through. These can be quite hard to fix unless you have an electronics background and the equipment to test and service it. I manage to get about 90% of them going again, but there are a few that are just not repairable, or will not be reliable enough if I do to supply a warranty with.

A new PM3 is so cheap if your in the USA and it is now a brillant monitor and worth the upgrade and you can use it with RowPro.

[dg211]

S1030899c.jpg (103.25 KiB) Viewed 7783 times

Hi Carl,

many thanks for your swift response.

I'm in the UK and PM3s are about £200 (~400NZD) here, so I'd prefer not to write off my PM2 just yet if it's at all salvageable. I've attached the best photo I was able to get of the board if that helps. I only have a little bit of experience with electronics, but I studied physics and computer science at university, so I am comfortable with technical stuff.

I tried drying it again with warm air from a hairdryer in case I had left some trace of moisture the first time round, and mysteriously it appears to work normally for a few minutes afterwards and then go haywire and then dead. I tried this once more and the effect seems to be reproducible. This might be an incredibly dopy idea, but is it possible there is a loose connection somewhere and a little bit of thermal expansion is temporarily making the connection good?

Thanks again for your help,

Dave

[Citroen]

Try contacting http://www.midlandrowerservicing.co.uk/

[Carl Watts]

Hi, it looks quite bad and I would normally pull the MAX859 and clean and or replace it. Check the resistance of the track between the top left battery terminal and the via on the board below the R46 (beside the C1). It is common for this to corrode under the lower right of the battery tab in the picture and go high resistance or open circuit. The battery leakage travels by capillary action under the components and eats the copper track.

If the PM2 works with heat and then gradually the screen fades then it is likley the MAX1044 / LT1044 is faulty which is out to the left of the picture.

[dg211]

Hi Carl,

are these the two points you mean? I get about 200 ohms, which seems rather high.

The screen didn't fade particularly gradually. A few random LCD segments lit up and then it faded pretty abruptly. The MAX1044 wasn't very near where the battery leaked and appears undamaged, could the problem be the tracks leading up to it rather than the chip itself?

Thanks a lot,

Dave

[Carl Watts]

There's part of your problem at least, it should measure like 0.3 Ohms or basically a short circuit between the points. The track also corrodes below the tab with the arrow. What I have ended up doing is taking a piece of thin enameled copper wire and run it direct from the battery terminal to the C1 point on the board. Solder the wire UNDER the board.

You still need more vinegar and a toothbrush to see clearly but the track by the tab looks all but gone.

Clean all the battery terminals, they may look clean but they can have a layer of near invisible stuff on them forming an insulator.

[LCGarage]

A new PM3 is so cheap if your in the USA and it is now a brillant monitor and worth the upgrade

After all my cleaning/ reconnecting my PM2 it just started to go flaky again. Could make out the readout if held at angle...but figured it wasn't worth another effort.

So decided to take Carls advice, again...ordered a PM3 today!

Good luck with your PM2, I think it's worth the effort, at least once!

[dg211]

Hi Carl,

sorry for not posting for ages - it took me a while to get hold of all the soldering equipment and so on, and then I was really busy for a few weeks.

I cleaned the board again and cleaned the terminals. The resistance between the two points you described is much lower after cleaning the terminals, about 3 or 4 ohms - should I still solder a connection between them?

Dave