#15 Kenwood TS-50 part 2 Display board repair

[Radio Tech]

In this part 2 of the TS-50 I troubleshoot the back light issue, determine the root cause and why it happed. Then repair the damage and see if the back light works.

I know I am not getting a lot od responses here on this site but I hope these videos are helpful to some.

 

[autotuner]

In this part 2 of the TS-50 I troubleshoot the back light issue, determine the root cause and why it happed. Then repair the damage and see if the back light works.

I know I am not getting a lot od responses here on this site but I hope these videos are helpful to some.

Good stuff Radio Tech, keep em coming. I allways get a sinking feeling when I see an electro has leaked, especially on the modern stuff with tiny tracks spaced half a molecule (or so it seems) apart.

 

[Radio Tech]

Yes those caps can be a pain on smd boards, causes a lot of damage. I will get a few more videos on this radio and have a lot more material I can cover on others. Plenty of stuff here to work on

 

[Robb]

Was that cap stressed into failure? Beginning to think so. I've seen these cap fail on video cards and repaired them; but never a leakage failure that turned into a trace failure.

 

[Radio Tech]

The caps are only rated for 16 volt. Some of these circuits have over 13 volts on them. So there is a bit of stress. Probably more due to age though, The rubber seal in the bottom dries out, air enters the cap and oxidation starts, and the electrolyte leaks out onto the board.

 

[Robb]

These type of caps serve two purposes. One, is to have a low ESR - which isn't really necessary in that circuit. The next is because they are small, is space a problem? But if it would fit, ya think putting a regular 25v cap of the same value might not be a better idea?

 

[Radio Tech]

Space is really an issue here. Standard caps are too tall to fit. also you can only solder them to the traces, would not take log for them to become loose or rip the small traces up, trace width is less than 0.01. Tiny little things.

Lets also not forget the production date of this rig. Although it has a modern look last production was around 1993-95. So she has a bit of age on her. So new caps will probably out live the processor.

 

[Robb]

I liked the part where you used a camera to zoom in on those traces.
That is one cool learning tool.

 

[Radio Tech]

I liked the part where you used a camera to zoom in on those traces.
That is one cool learning tool.

That was done with a Dino-lite pro. Very handy little USB microscope. Not cheap but less than a Mantis..

http://www.microscope.com/dino-lite...-eFNjl0W36GPsNU9hzrTfHA5Aqs2WqgIDORoCi9zw_wcB

 

[ZL4MBW]

In this part 2 of the TS-50 I troubleshoot the back light issue, determine the root cause and why it happed. Then repair the damage and see if the back light works.

I know I am not getting a lot od responses here on this site but I hope these videos are helpful to some.

Thanks for your very well presented repair and explanation during. well done I learned from this. cheers Mike

 

[Radio Tech]

Thanks Mike

 

[ZL4MBW]

Thanks Mike

I opened up the TS 50 to examine the no display problem I have and discovered none of the errors you pointed out thankfully however after carefully removing the LCD display I looked closely at PL1,PL2,PL3,PL4 light bulbs and saw that PL1,PL2 & PL3 filaments were all broken and needed replacement. See images below Its unlikely I would get those same replacement bulbs so what would you recommend as an alternative option?
I was advised by one amateur tech to fit white or yellow LED's but I will need to bypass the dimmer circuit for the LED's to work:

This is what he said:
[remove the globes and the two resistors and wire in the led's with a 1k resistor on each going to a 12v rail the ground connected to the ground side of the globes old position]
Unfortunately he could not recall where on the circuit board he connected for a "12v rail" source and advised I work it out myself. So my question to you sir is if you have any idea where on the board I may use for this 12V source. I dont have a separate 12v supply on my work bench to do a trial and error and only have the main 13.8v rigs supply on the radio desk 2m away. This is something I will have to rectify soon. Await your response. Mike