Electronics help needed

[johnie]

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.

[bargee99]

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]

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.

[GrahamP]

Johnie,

If I was having difficulty finding a replacement I would attempt to solder fine wires to the component. If that worked I'd put a blob of epoxy resin on top to hold things together.

Graham

[johnie]

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]

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?

[Chick]

I may have send me a message.

[bargee99]

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]

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]

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]

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

[johnie]

Thanks Foxy, that's great! I'll need to collect one of the working ones sometime next week. I'll buy you a pint in the EDT as thanks. Is it a quick thing to do the measurement?

[DulwichFox]

Just a few button presses to select range and test..

I have the instructions.

Foxy.

[johnie]

Brilliant, thank Foxy. I'll PM you when I have collected the unit.

[natty01295]

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