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O.K. will check the fuse and let you know.

Which country are you in?

 

Is it R8 the Blue one, looks like 1.1K ohms 1%, does it feed one of the opto-couplers?

 

Which country are you in?

United Kingdom

The T2AL 250v which says T2 0A 250v on the fuse, seems o.k.

 

Is it R8 the Blue one, looks like 110 ohms 1%, does it feed one of the opto-couplers?

Yes R8 is the resistor that's blown in all 3 receivers, it's connected to the 'opto-couplers'.

 

United Kingdom

The T2AL 250v which says T2 0A 250v on the fuse, seems o.k.

If worse comes to worst you can always post one to me as it will be so much easier with it on my bench. Just send me a personal message and i will give you my phone number if that helps at all .
Preferably one that has not had anything done to it.

 

If worse comes to worst you can always post one to me as it will be so much easier with it on my bench. Just send me a personal message and i will give you my phone number if that helps at all .
Preferably one that has not had anything done to it.

Yes, that's a possibility, lets see how we get on.

Because it's re-booting, could the power supply be going into 'protection mode'?

 

Yes, that's a possibility, lets see how we get on.

Because it's re-booting, could the power supply be going into 'protection mode'?

If it is cycling on and off then yes, but there could be numerous reasons for that. I will be popping into my old business this afternoon and will have a look for the circuit diagram which would help a lot so bear with me and I will get back asap.

 

If it is cycling on and off then yes, but there could be numerous reasons for that. I will be popping into my old business this afternoon and will have a look for the circuit diagram which would help a lot so bear with me and I will get back asap.

That would be good, circuit diagram.

 

That would be good, circuit diagram.

I think we have something similar, I'm out with family today so will study it tomorrow and get back to you

 

How did you determine the value of R8? Can you check that the opto coupler it is connected to is not short circuit pls. I'm looking at a circuit of a similar psu,

 

How did you determine the value of R8? Can you check that the opto coupler it is connected to is not short circuit pls. I'm looking at a circuit of a similar psu,

The R8 had blown and ballooned, scrapped the ballooned part off, the colours weren't clear, so had to guess. I'll check the opto coupler and report back.

 

R8 (1.1K) could be used with R9 and IC2 the voltage regulator Tl431, to set the output voltage with the opto-coupler, if it's pulsing on/off could be going into overcurrent shutdown, or overvoltage, if you can trace the tracks of the opto-couplers to the resistor r8 and IC2 or take a closer picture of the trackside.

 

R8 (1.1K) could be used with R9 and IC2 the voltage regulator Tl431, to set the output voltage with the opto-coupler, if it's pulsing on/off could be going into overcurrent shutdown, or overvoltage, if you can trace the tracks of the opto-couplers to the resistor r8 and IC2 or take a closer picture of the trackside.

Hi dave, yes exactly that, I have a little process I would like him to follow step by step without jumping too far ahead so that we don't confuse him and lose track of where we are going. I have the schematic of a similar power supply and I think you are right. Hopefully we can get it sorted without him doing tests whilst connected to live mains

 

I think this is what you wanted to see.

 

I think this is what you wanted to see.

yes thanks, it is a little different physically, but that should not be a problem.
as Dogeydave suggests, if the resistor has failed because of a short in the opto coupler, It is very likely that IC2 kia 431 is also faulty. carefully measure the opto couplers for shorts and ic2. If they are damaged, there will be a few other things to check before just replacing them.

 

The black line shows how I'm testing the IC2 / IC3 with a Autorange Multimeter.

I've used ohms (not sure if I should be using ohms) on the Autorange Multimeter to check the IC2 / IC3,
there is no reading If I'm checking it correctly.

I've also checked the same IC2 / IC3 on one of the other circuit boards, I do get readings.

Just to add that the receivers display a F100 error message, but still work when that is displayed.

 

Ok, well at this point we could go round in circles for a week and get nowhere. I would be happy to have a look at them for you f.o.c as long as you are happy to pay postage and any parts i have to buy. the best way to go about it would be to send me the one you are working on, (complete receiver) and a power supply from one you have not touched.
Send me a personal msg and I will give you my contact details. Once we get one sorted I will detail to you what I've done so that you can fix the others.
I don't often offer this, but it has intrigued me and as I'm retired, doing the odd repair keeps the brain from (totally) seizing up
Also I am currently posting a thread on my experiences so that the process can be followed by others who may be interested.

 

You cant test opto-couplers from input to output, you test the transistor C/E terminals for shorts or open circuit when voltage is applied to the led.

Looking at the pcb R8 is on the Led side and looks like the series resistor for the opto-coupler, so chances are the opto-coupler is duff too.

 

You cant test opto-couplers from input to output, you test the transistor C/E terminals for shorts or open circuit when voltage is applied to the led.

Looking at the pcb R8 is on the Led side and looks like the series resistor for the opto-coupler, so chances are the opto-coupler is duff too.

Yes but why and what else? the problem here is the info keeps changing, now we know it boots up with an error code. I am very unsure about the value of R8 as a similar psu has a 6.8k resistor here. We need to know the cause of the component failure. If echat takes up my offer, I will post the outcome on here..

 

Yes but why and what else? the problem here is the info keeps changing, now we know it boots up with an error code. I am very unsure about the value of R8 as a similar psu has a 6.8k resistor here. We need to know the cause of the component failure. If echat takes up my offer, I will post the outcome on here..

The information has not changed, I stated initially that it has an 'auto-reboot problem'. The error code is meaningless as that could be quite a lot of things. As for sending it off, it doesn't make sense. The additional receivers were picked up for a few pounds just for parts. The technology is old. I thought rather then buy another receiver I'd try to fix it. I've had it in the re-boot state for a couple of years, it's been sitting around.

But I take your comments onboard.