Help identifying crystal - broken off Mercedes Sound 5 Headunit

Thread Starter

Jim01

Joined Jan 4, 2020
11
Hey guys,

I was adding a fan inside a mercedes sound 5 headunit and inadvertantly broken off a surface mount crystal.

I've attached some photos but it has "41.600" written on it, followed by a box with a resistor looking symbol inside it, followed by a ":9y" at the end.

I have tried dodging it back up onto the board to no avail.

Googling doesn't seem to turn anything up, but I may not be searching the right thing, I am assuming 41.600 is a frequency.

What the crystal looks like

I'm located in Australia by the way.



Cheers everyone
Mod: tidied your image.;)
Img_1367[1].jpg
 

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Yaakov

Joined Jan 27, 2019
3,161
It is a 41.6MHz crystal. The lead length will be critical to proper operation, so even if the one you have is working, that repair will probably not. It has to be mount to the surface like it was to know if that crystal is operating.

The problem I found was not locating a 41.6MHz crystal but finding one in that package.
 

Thread Starter

Jim01

Joined Jan 4, 2020
11
It is a 41.6MHz crystal. The lead length will be critical to proper operation, so even if the one you have is working, that repair will probably not. It has to be mount to the surface like it was to know if that crystal is operating.

The problem I found was not locating a 41.6MHz crystal but finding one in that package.
Hi Yaakov,

cheers for the response, interesting read about the lead length!

aa I said, the repair to get it back on the board was dodge.

what where you able to find?
 

Yaakov

Joined Jan 27, 2019
3,161
Other surface mount packages. If you hot air solder that one back, it might work fine. They are pretty rugged.
 

Thread Starter

Jim01

Joined Jan 4, 2020
11
Other surface mount packages. If you hot air solder that one back, it might work fine. They are pretty rugged.
I’ve broken the solder tabs off that one, I’m not sure if you can see in the photo but I’ve soldered wire to the bottoms of the crystal, twisted the wires round to then make it easy to solder back to the board.
 

Yaakov

Joined Jan 27, 2019
3,161
Hello,

@Yaakov , I saw the page to, minimum order 1000 pieces.

Bertus
For some reason, that package doesn't seem to be very popular any more and everyone has them on backorder. I don't think an alternative package is likely to be workable. I wonder if the current part can be salvaged.
 

Thread Starter

Jim01

Joined Jan 4, 2020
11
He soldered leads on, he could solder tabs in their place.
Where can I get a hold of tabs?

I found it very difficult to solder those leads on without soldering the crystal itself, is it possible to damage the crystal by applying too much heat with the soldering iron (I'm assuming not given you said they are pretty rugged)?

@bertus does it look to you like the three traces directly under the X201 legend might be cut?
Very good pickup!

The drill bit has nicked 2 traces, I'm pretty confident however they are only grazes, and haven't actually cut through the traces themselves.
 

Thread Starter

Jim01

Joined Jan 4, 2020
11
Forgot to ask: I'm pretty sure this is a long shot but what are the chances of using a surface mount crystal exactly like that but with a similar frequency?
 

Yaakov

Joined Jan 27, 2019
3,161
Forgot to ask: I'm pretty sure this is a long shot but what are the chances of using a surface mount crystal exactly like that but with a similar frequency?
It has to be the same frequency, and some other parameters—an exact replacement. It's not easy to work with SMD without the right equipment, including a magnifier. If I was in your position, I'd probably try some copper tape to fabricate my own tabs. It's going to be hard no matter how you look at it.

Do check the continuity in the traces, though, just be be sure.
 

Thread Starter

Jim01

Joined Jan 4, 2020
11
It has to be the same frequency, and some other parameters—an exact replacement. It's not easy to work with SMD without the right equipment, including a magnifier. If I was in your position, I'd probably try some copper tape to fabricate my own tabs. It's going to be hard no matter how you look at it.

Do check the continuity in the traces, though, just be be sure.
UPDATE:

The radio is now working properly again.

I pulled it apart, and found that the 2 traces where indeed broken, given how close together the traces are I felt they where too close together to try repairing, I instead carefully soldered 2x hookup wires from one point to another on the board.

As for the crystal, your suggestion Yaakov worked EXTREMELY well! a quick continuity test confirmed I had actually soldered the makeshift lead to the body of the crystal, so after carefully applying copper tape underneath getting it back onto the board was very straight forward!

For those who ever find this thread and wonder wtf was going on here, the headunit in a mercedes sprinter/vito sits right beside the heaterbox, and because of this the unit is subject to a bucket load of heatsoak!

The issue with my particular radio is after a while the radio typically "freezes", kinda like a computer, none of the buttons work, won't turn off at the press of the off button, the only way to fix it is to pull the fuse out from the fuse box in the bottom left corner of the car under the glovebox (Right hand drive vehicle) and put it back in, effectively re-setting the radio.

There is a small fan external from the radio that does sit in the bottom right corner inside the compartment where the radio slots into, but doesn't really push a lot of air, so I thought adding a fan inside the radio itself might help keep inside the unit cool and prevent the radio from "freezing" or locking up.

I also added some heatsinks to a couple of the chips I found, the digital signal processor, and another chip that I couldn't find any information for on google.

I'm not exactly sure where the CPU is on this unit, it is possibly underneath that metal box that can be seen in some of the photos.

It was when I was drilling all the holes in the metal casing for the fan that I got into this mess with the crystal and broken traces.

For now the workaround is wire a push to open button inline with the 12v power feed into the radio, effectively acting as a reset button, much easier than constantly removing the fuse from underneath the glovebox!

I have considered completely disassembling the unit, sticking it in an oven to "reflow" the solder on the board, I felt this was a bit too much, maybe this will fix it? maybe it won't?

I have attached some photo's of my handywork, all suggestions, criticism, etc welcome :)

Massive shoutout to Yaakov for all your help!
 

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