mazda key fob crystal id or source

[ditzen]

hi all. this is my first post here. Might be too basic for you lot.

i have an old mazda xedos with a 2 button key fob for the cental locking that the wife dropped. no led's on it
seems to have a ceramic resonator next to the crystal.
battery is new.

my guess is it's the crystal, but. i can't seem to be able to read it correctly or it's a special freq.

the numbers are "P 4180B symbol". symbol looks like a C with a small m inside the void of the C. The above is printed on a plastic sticker and there is nothing else under it.
it's a small package with four pins. three of which are solderd together.

i have tried to find it and am floundering hopelessly proper fool style.

the car is an automatic so i thought i'd get the fob going again and re wire it to start and stop the engine for the winter. ( with some added circuitry)

thanks in advance

 

[markm6164]

Got any clear pictures or the circuit board? I run an auto locksmith company and would like a look please.

 

[ditzen]

pictures

front and back pics.
the mfr logo on the crystal is the same as the one on the ceramic resonator? or cap

 

[davenn]

its definately a crystal/ceramic resonator

tis difficult to know if the 4180 is 4.180 kHz, MHz or maybe 418.0 MHz ??

Dave

 

[markm6164]

Are there any markings under the sticker directly on the can? Also have you checked the coil antena? That's a common failure point.

 

[CocaCola]

tis difficult to know if the 4180 is 4.180 kHz, MHz or maybe 418.0 MHz ??

If it's a pre '95 UK vehicle they were 418 MHz

 

[ditzen]

Hey, thanks for your input all.

no there is nothing under the sticker at all.

the coil was squashed so i straightened it. it seems fine. i squashed it after i opened the case.

418 Mhz sounds like the thing worth trying. but i've trawled about with very little to show.

i believe i'm looking for a saw resonator in F11 case style judging from this datasheet i got from Advanced Crystal Technology.
rapid electronics don't seem to stock it. they are my most familiar supplier.
i'll look at the others.

http://www.actcrystals.com/_files/f...l_Technology/datasheets/ACTR418,418_0,F11.pdf

 

[ditzen]

useless
i've drawn a blank. i'd stand a chance if i wanted 10k of them probably.

my gut feeling is that i don't know what i'm doing and i'm missing the obvious.

i flunked out of my electronic eng at uni too soon.

any pointers of any kind appriciated.

 

[(*steve*)]

Carefully (and under high magnification) look at each solder joint on the board.

SMD devices without leads can be under very high stress (caused by differing expansion rates of components and the board) and it is not unlikely that the shock of being dropped has broken a marginal solder connection.

What you're looking for are joints that appear to have no (or very little) solder, and those that appear unusually dull.

Once you find them, touch the end of the component with a soldering iron and the joint will be repaired (you may need a very small amount of solder).

If you're lucky it will then spring into life.

 

[ditzen]

thanks steve. i've looked at it with a watchmakers eyeglass. can't see a dry joint or crack. i might need a higher magnification though.

1- do you think it's more likely than the crystal though?
2- or just just the best option at my current position?
cheers

 

[(*steve*)]

I typically start with the easier stuff first. No point going to great effort locating a part when the solution may be a lot simpler.

 

[markm6164]

Have you tested the remote output siganl at all. Could it be that the remote is working fine but just needs re-coding to the car? I see this alot. I have a signal tester but usually just sell a new remote if the remote isn't outputting a sinal and has had the battery changed and there isn't anything obviously wrong.

 

[CocaCola]

Have you tested the remote output siganl at all. Could it be that the remote is working fine but just needs re-coding to the car? I see this alot. I have a signal tester but usually just sell a new remote if the remote isn't outputting a sinal and has had the battery changed and there isn't anything obviously wrong.

Good point, my local autoparts store has a little 'battery' testing station where you hold the remote close by and press the button, it will indicate if there is a good transmission... A quick test if you can locate such a test station locally...

 

[ditzen]

right-o suggestions noted.
waiting for some 20x mag glasses.