I have a receiver and transmitter that are used in remotes for sporting clays that I need help repairing.

The remote system does work but effectively has no range.

If the antenna of the transmitter is placed so it touches the antenna mount on the receiver PCB (which is shown in the photos) it works. IE -- the LEDS light and the relays operate. If the transmitter is a few inches away it does not work. Same conditions if receiver antenna is attached.

Transmitter was ruled out as part of the problem as it operates other receivers correctly.

Photos are of receiver board.

Things I have done/tested-

A visual inspection of both receiver board checking for any physical damage.

Tested that 5 volts is coming from voltage regulator and is present at both side of the relays. The transistor package IC3 on the other side of the relays goes low, via signal from IC labeled V2, and allows the relays the operate. Also tested electroytic capacitors with ESR and they test good.

What may cause this unit to operate this way? What can I test in order to improve/restore the range of the remote?

I am self taught with no previous background in electronics, so take that into account with any explanations.

Thanks for any help you can give.

 

Do you have the manual for the devices?

Get it and follow the troubleshooting section in it. The programming (dip switch) could be incorrect. Once that is verified, then the troubleshooting can begin.

 

Yes one of the first things I did was search for a manual. There is none to be found through vendors or the internet. I believe that it was a cheap knock off that came with little to no documentation. It was sold through a third party vendor who no longer sells or services the units.

It did come with a single sheet from the vendor with the DIP switch settings. I verified they were correct. I also verified them against a known, properly working unit that I have.

If you can help me further I would appreciate it.

 

Do you know the model number?

Do you know how to test transistors with a multimeter?

 

I looked for a model number when looking for a manual. Unfortunately there are no markings on the case and there is no literature that I can find at this point. They were purchased 5-8 years ago so whatever paperwork came with it is gone.

I do know how to test transistors with a DMM. The power transistor on the heatsink is a TIP 122 Darlington transistor and it tests good as compared to a known working TIP122.

 

Anyone?

 

I notice the 1c2 chip has a socket. Maybe try swapping the chip with a known working remote.

 

Have you checked the continuity of the dips switches? Just throwing a few ideas out there. Good luck.

 

Thanks for the reply thomas. I switched the socketed chip with no sucess. I dont suspect the dips but I can check them.

I am wondering about the resonators. There is are resonators (and a crystal at X3 AEL 26.590 which is presumably the clock for IC1) at X4 (marking 400G.625), X1 (marking CDBC28), and X2 (marking LTM 455EU). Do these play into frequency amplification that may affect the range of the circuit?

 

I do not know. That's out of my scope at the time being. What is ic1? Do you have a data sheet? I would review the data sheet and trace from there. I hope you get some feedback from some of experts on the site. I'm here for the same reason to learn. I'm very interested in your challenge and hope you solve it.

 

That crystal is set for 400.625 MHz.

 

What about using a car radar detector as a range finder? iPhones 4 camera works too but I think the timing would be near impossible. It may verify if a signal is sent and verify if it is an the amplification issue you believe.

 

What about using a car radar detector as a range finder? iPhones 4 camera works too but I think the timing would be near impossible. It may verify if a signal is sent and verify if it is an the amplification issue you believe.

I jumped to the transmitter. Please disregard.

 

And IR.

 

Duff receiver, that will be IC1, the other chips Ic2,5 will be the signal decoder (dip switches)...

 

Thank you for the post Dave.

My next challenge will be finding a replacement receiver. It has the marking 1689 07 (07 is underneath 1689)

I will be checking Mouser later today to see what I can find. If anyone has other resources/advice for ID the chip I would appreciate it.

 

So far I am unable to find anything at Mouser or Digikey plugging in rf receiver 1689 07 and many different search variations.

Anyone have advice on finding a substitute part?

 

Its probably an in-house design, you probably won't be able to get one.

 

Its probably an in-house design, you probably won't be able to get one.

I was afraid that was going to be the case....

 

I know very little about these matters (I did get 21/25 at trap once) and yet that does not seem to stop me from responding

It seems like what you and other folks are suspecting is that the amplification step in the receiver is what is failing. Is it possible that the center frequency (for the receiver sensitivity) has drifted? I don't see any potentiometer on the board (unless it is between c3 and c4) that could be adjusted to see if that would increase the range. Alternatively, there may be one on a transmitter that could be altered to see whether that would directly have an effect on the range.

Would a device like this https://www.amazon.com/Champion-Tra...coding=UTF8&psc=1&refRID=D0V1NR94ZQZ12HT1KMEP be more time and cost effective?

What about replacing the receiver by one of these low end ones with relays http://www.banggood.com/4-CH-Receiv...-Switch-12V-315MHz-p-917213.html?rmmds=search