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Electronics help needed

johnie

By johnie
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johnie

johnie

Posted
Posted

Can anyone with an understanding of electronics help me? I'm trying to fix an old garage door style remote control.


A component has snapped off the circuit board, and I'm not sure what it is. I think it may be the transmitter crystal or something. It has (had) two legs - these have snapped. It is labelled 57.768 UNI 97 - A. I've attached a couple of photos. The component sat next to the green thing in the area labelled X1.


Thanks for any help.

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bargee99

bargee99

Posted
Posted
Hi Johnie. X refers to a crystal. It determines the frequency that the circuit resonates at so that it only operates the appropriate receiver. Without further investigation I would guess it has a frequency of 57.768MHz which are the numbers on the can. Hope it helps.
ianr

ianr

Posted
Posted
It looks to be an oscillator from the HC-49U series: http://www.dutchforce.com/~eforum/index.php?s=2e1b2f0b4cdbaa50b92f083a4a057de0&showtopic=980. They seem to be available for a pound or two: just search on HC-49U. The problem is finding one of the right frequency (and maybe other parameter values), but there are several distributors you can ask.
johnie

johnie

Posted
  • Author
Posted

Thanks all for your help! From my research so far I've not found anything with the 57.768MHz frequency, but I'll press on.


Graham, I had considered that, but the breaks are so clean there is nothing to solder to, at least not with my rubbish skills and failing eyesight.

ianr

ianr

Posted
Posted

You could always try a bit of surgery on the can to gain access; even buy a few of the type to experiment with first.


Speaking of which, I'm thinking of trying to replace a few suspect capacitors on my PC's motherboard, after it ceased functioning without any obvious cause. But I'd prefer get some practice first. Does anyone have a derelict motherboard they don't want that I could use?

bargee99

bargee99

Posted
Posted

Hi Johnie,

CPC sell the same kind of crystal for 70P each but only have them up to 50MHz. If there is a similar crystal in the receiver you may be able to pair them up by changing the one in the receiver as well to make them work together,

http://cpc.farnell.com/ael-crystals/x50m000000l001/crystal-50mhz-hc49u/dp/SC08184

Abe_froeman

Abe_froeman

Posted
Posted

I would have thought yo would be able to buy an entire replacement zapper for less than a tenner on ebay or similar. Is there any text on the casing that would indicate what make / frequency it is?


I did this once with a replacement for an electric gate remote and all I had to do was put a battery in and set the switches numbered 1 to 10 to the same position as the old remote

johnie

johnie

Posted
  • Author
Posted

Hi Bargee


The remotes are for security shutters on an office block. There are two working remotes and this broken one, so I can't modify the receiver. But a good suggestion.


Hi Abe


Yes, you would have thought so, but no such joy. The shutters are about 30 years old I think. The fact I can't find a crystal with the 57.768 anywhere makes me think it may be a red herring, as I have found a couple of 7.68 Mhz ones (at 44p with ?12.50 postage!).


Does anyone know if there is some way to measure the frequency from one of the working remotes?

DulwichFox

DulwichFox

Posted
Posted

johnie Wrote:

-------------------------------------------------------

> Hi Bargee

>

> The remotes are for security shutters on an office

> block. There are two working remotes and this

> broken one, so I can't modify the receiver. But a

> good suggestion.

>

> Hi Abe

>

> Yes, you would have thought so, but no such joy.

> The shutters are about 30 years old I think. The

> fact I can't find a crystal with the 57.768

> anywhere makes me think it may be a red herring,

> as I have found a couple of 7.68 Mhz ones (at 44p

> with ?12.50 postage!).

>

> Does anyone know if there is some way to measure

> the frequency from one of the working remotes?


Hi Jonnie. I have a device that does just that.


http://mklec.com/image/cache/data/etc/gooit_frequency_counter-7-500x500.jpg


You are welcome to borrow it. You will need to supply a PP3 9v battery


DulwichFox

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