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CEM Speaker replacement?
Posted: Sun Mar 24, 2024 12:17 am
by WillC9303
Hi all
I think I made a topic on this quite a while back but I'm pretty sure the speaker in my CEM is broken. All I hear when I put my indicators on is a faint mechanical click which obviously isn't coming from the CEM. Not only that but the 'beep' that should sound when you hold down the heated rear window doesn't happen.
I know that the indicator chime varies between model year, but I'm 99% sure that L reg (1993) cars were all fitted with the synthetic indicator 'tick' sound from factory.
Is a CEM speaker replacement something difficult to do? I obviously don't want to destroy the 'brain' of my car, so will only attempt if its an easy fix.
Really I just want to put a stop my passengers assuming I'm not indicating when I am
Thanks!
Re: CEM Speaker replacement?
Posted: Sun Mar 24, 2024 8:35 am
by dragonflyjewels
Snazzy is also an L reg, and her indicators went really quiet recently as well. I hadn't got round to trying to find out why yet, so I'll be watching this thread.
Re: CEM Speaker replacement?
Posted: Sun Mar 24, 2024 12:22 pm
by mandi
hi
i repaired in the meantime some CEMs.
no CEM 3 but CEM 1 and 2.
not knowing which piezo is mounted in CEM3 i want to mention that in min 2 cases the soldering was failing.
i think it's a mechanical problm - cannot be of current and heat.
resoldering solved the problem. the piezo part itself is in general quiete insensitive and robust.
mandi
Re: CEM Speaker replacement?
Posted: Sun Mar 24, 2024 7:42 pm
by WRDendy
I agree with Mandi - not much to go wrong with the piezo itself, but yet another point on the 480 electronics where dry joints can be an issue.
I happen to have a CEM 1 on my bench, I imagine that an L-reg will be a CEM 3, but similar enough layout:
The piezo sounder is the black circular thing with the hole in it on the left, found behind the 'speaker grille' on the CEM housing. It's a self-drive type with 3 connections, highlighted on red below on the opposite side of the board:
You can see that this one does in fact have evidence of dry joint syndrome setting in, particularly on the left-most joint. Re-flowing all three would probably sort out any issues this one has. If the piezo sounder were to be actually dead (unlikely but possible), then it would be very straightforward to desolder it and replace it, either with one salvaged from another CEM or a new one off the shelf. Don't have a part number to offer you right now I'm afraid but could probably be found relatively easily.
Bottom line - try reflowing the joint first. See the instrument cluster repair thread for more info on that if you're not up to speed on it already!
Bonus thought: If you're reflowing and/or desoldering it then nothing stopping you mounting it somewhere else in the car, maybe run a few long wires and put it in the passenger headrest just to keep them really reassured
Re: CEM Speaker replacement?
Posted: Mon Mar 25, 2024 4:25 pm
by WillC9303
WRDendy wrote: ↑Sun Mar 24, 2024 7:42 pm
I agree with Mandi - not much to go wrong with the piezo itself, but yet another point on the 480 electronics where dry joints can be an issue.
I happen to have a CEM 1 on my bench, I imagine that an L-reg will be a CEM 3, but similar enough layout:
The piezo sounder is the black circular thing with the hole in it on the left, found behind the 'speaker grille' on the CEM housing. It's a self-drive type with 3 connections, highlighted on red below on the opposite side of the board:
You can see that this one does in fact have evidence of dry joint syndrome setting in, particularly on the left-most joint. Re-flowing all three would probably sort out any issues this one has. If the piezo sounder were to be actually dead (unlikely but possible), then it would be very straightforward to desolder it and replace it, either with one salvaged from another CEM or a new one off the shelf. Don't have a part number to offer you right now I'm afraid but could probably be found relatively easily.
Bottom line - try reflowing the joint first. See the instrument cluster repair thread for more info on that if you're not up to speed on it already!
Bonus thought: If you're reflowing and/or desoldering it then nothing stopping you mounting it somewhere else in the car, maybe run a few long wires and put it in the passenger headrest just to keep them really reassured
Thank you very much! I will give it a try when I wake my car up again in April.