Repair of an R-link box, need help.

[Alfaholic]

I bought a broken sdt-ti kit a while back, i have been refunded the money i payed and i get to keep the broken unit.
Since i get to keep it i want to try and repair it, i have bought a working unit from a phorum mmber so i can test on that and see if the values are the same on both.
My problem with the unit is that the display blinks and always show 7.4volt, on the r-link box the led showing what voltage range its in dont work i have tested the led and it works.
My problem is im not sure where i should begin, there is nothing wrong with the display because it works on my other r-link box, i have tested all the resistors but how do i check the chips and what are the different chips for i have put arrows on the chips can i buy new chip for it and do they come programmed or do the need to be programmed?.

If anyone on here ever done a repair on a R-link please tell me i need all the help i can get, i will start testing the chips later but im not sure how they are testet i were thinking on testing what pins get earth,power and wich are connected together i then will compare it to my working unit.

[vwdude]

To get more info on the chips, search them on digikey and check out the schematics. It should have a pinout diagram.

You also might consider checking the diodes, resistors, transistors and caps for proper function. I've never repaired on of these but I've repaired my TBAt and my SLD44.

[ttocs]

I thought I had a copy of the r-link schematic but after digging around I can't find it. It could be as simple as replacing that led. I was trying to break it down to hook it up to a new elite amp and if I remember correctly one or both of the leds in that circuit powered a different portion of the circuit.

[Alfaholic]

Im checking now and i see that the one i put the yellow arrow on is the display driver and they are in stock, the blue on are not in stock anywhere but i found some on ebay but they are 24vdc mine are Omron G5A 234P and got 1539EA1 on the side.
Im also having problems finding the red ones they got QTC 4N35 934Q, i will order the transistors and the display driver from digikey and try to get the rest somewhere else.
Does anyone got some info about the three feet leds i know the ones showing voltage range is yellow and red but what voltage are they and are they hard to find?

[Alfaholic]

I thought I had a copy of the r-link schematic but after digging around I can't find it. It could be as simple as replacing that led. I was trying to break it down to hook it up to a new elite amp and if I remember correctly one or both of the leds in that circuit powered a different portion of the circuit.

The leds are fine its not getting any power so the problem is somewhere else and after what i can see the display driver chip that i put the yellow arrow is where the leds get there power.

[Alfaholic]

I can find many 4N25 Optoisolators but i cant find the QTC 4N35 924Q, one of my board on the brooken one got two 4N35 0201K and one 4N35 0150K I think i can use any one of these 3 optoisolators but i dont know if i can use others on digikey because i cant find the value on the ones i got.

[trickyricky]

Don't go ordering parts so quick...

Let me get this straight...the whole unit is not powering up? In other words your not getting any oscillation in the power supply?

Check Q13-16 and their 2.2ohm fuse resistors.


The blue arrow is a relay, I doubt that is bad...one way to find out is to have it engage (if it doesn't engage/click, then it's the relay) if it engage and there is no signal on the other side then the relay is faulty (bad contacts inside). Again I doubt this is even faulty....Do either of the relays engage/click?


Don't forget to check Q12 (which I think is the cause of this...if its not power it up at all)...this is a very easy to find component..I have a few and can include it in the package am shipping you tomorrow (I already got it packed and ready to drop off) and the diode that goes from ground/- to positive/+12v.

[Alfaholic]

Don't go ordering parts so quick...

Let me get this straight...the whole unit is not powering up? In other words your not getting any oscillation in the power supply?

Check Q13-16 and their 2.2ohm fuse resistors.


The blue arrow is a relay, I doubt that is bad...one way to find out is to have it engage (if it doesn't engage/click, then it's the relay) if it engage and there is no signal on the other side then the relay is faulty (bad contacts inside). Again I doubt this is even faulty....Do either of the relays engage/click?


Don't forget to check Q12 (which I think is the cause of this...if its not power it up at all)...this is a very easy to find component..I have a few and can include it in the package am shipping you tomorrow (I already got it packed and ready to drop off) and the diode that goes from ground/- to positive/+12v.

It powers up and it gives me status led thats blue the problem is that it does not give a voltage reading its always 7.4 and the led that shows voltage does not light up at all but the led is working i have tested it.
I have tested all transistors,capacitors and all the resistors they are all the same value on the working r-link and the broken one, i think the problem is in one of the ones i put n arrow on but im clueless when it comes to testing them i know i have tested the resistors,transistors and caps the right way.

[Alfaholic]

I have tested the ones you told me to again and all are ok the problem is the showing of voltage both to display and led the display turns on and of like a indicator relay on a car so something tells me that it may be a relay causing it.

[trickyricky]

Did you check Q7 and the one below it?

[Alfaholic]

Did you check Q7 and the one below it?

Yes i did check them but i will test them again when i get of work, thanks for your help