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How to: Resolder the BM24 amplifier dry joints

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My E39 530i has the BM24 amplifier. For the past 1 or 2 years it has been intermittent, cutting out then coming back on again especially on rough roads.

I have seen the companies advertising their repair services, ranging from £30 (+ postage both ways) up to over £100. I have never seen a DIY guide on t'internet, just recommendations to "re-solder the dry joints". Finally I found a brief set of instructions with a photo on m3cutters.co.uk so I though I'd give it a go. My one and only attempt at soldering was in a 5th form physics lesson but how hard can it be.

The answer is dead easy - It took much longer to remove the unit from the car than to open it up, re-solder it and put it back together.

How to -

Undo the 4 x T8 torx screws

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Prise the top off

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Take out the circuit board

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Turn it over

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These are the joints that are dry (taken from M3cutters)

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Re-solder the 4 joints - add a little extra solder

P6280272.jpg

Then put it all back together - couldn't be easier

My radio is working fine, hasn't cut out for a few days now.

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Antimony, I just did this fix on my 530 and it's not cut out since. it's been getting worse over the last few months so I was all set to put in some research time, ask a few questions and muddle my way through when I found your post. Much gratitude to you my friend for taking the time to post the procedure...I'm off to the bar, what's yours?

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Nice job.

 

I must say though, the soldering on the boards from the manufacturer is quite poor, dry joints, a rooky mistake.

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It's the combination of vibration and heat cycling that makes the joints become dry over time, the fault was not present at time of manufacture. It's a metallurgists fault for choosing the wrong type of solder.

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I've been driving around for months with the radio intermittent...  and today I finally fixed it, thanks to Antimony for the excellent pictures!

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Just done the repair on my e39 530. It now works spot on. Thought it would be a bit tricky as the last time i done soldering was at school. Added bonus is the 6 disc cd player now works aswell. Many thanks antimony.

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Usually either the rear wind heating element (which is used as the antenna) or the diversity amp in the C pillar.[/quote

Have a spare amp, bought it two weeks after the car, but not had the time to fit it!! Lol

YNP

Content provided by this user should not be considered correct due to the fact he's a raving fruitloop.

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Just wanted to say thanks for this. My stereo was driving me nuts, cutting in and out all the time. Followed this and it completely resolved the problem! :)

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Hello

Are there any after photo's of the soldering. I want to do this myself but don't know how much i should use. Or does one just heat up the solder that is already there?

 

Thanks in advance.

 

Lee

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You're re-flowing the solder that's already there but you'd always have a length of solder in your hand anyway to make the joints good again. The new solder 'refreshes' the old. Just watch a YouTube video on soldering a circuit board, it's dead easy once you get the hang of it.

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You need solder with flux in it, look for multicore solder - with plenty of lead in it :smile:
 
Watch out for plumbers flux as it's usually acidic :sad:

Edited by know-dice

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is this just for the radio cutting out all together or as i have sound loss from one side please help its driving me nuts, thing is i dont have an amp, must be a different design my radio is flat pin

Edited by dave16v

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Hello there

re-flowed and added a bit of solder on each joint and still have the same problem.

Borrowed another radio module that i know works, as we took it out and installed it in my car instantly.

Guess what? The same problem.

I think i read somewhere, that a loose connection to a speaker, can cause this problem.

Has anybody else heard of this?

Also is there a way of testing if there is a break in the wires that run to the Radio Module.

 

Any help would be greatly appreciated.

 

Many thanks

 

Lee

Edited by lee-clark61

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Do you have DSP or Hi-Fi? If so check the amp, and connections to it, that's mounted on the passenger side, behind the Nav computer.

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