Help! Repairing water damaged PCB from Massage chair.

[dorke]

Jona,
Don't ever think about "taking off every component on this board cleaning it up and re-soldering it".
That is not the way to fix stuff...probably the safest way to turn this unit into junk.


"I was going in to take out all the diodes with my soldering tool to test them and there was a bad arc from my tool to the board. Somebody had forgotten to turn off the power to the board.Some of the traces melted and there was a blown fuse. I patched up the traces and replaced the fuse.

Now the relays don't work any more with the remote. Three of them work when use the ohm meter to connect +12v to the base of the transistors. The fourth does not even though I have changed out the relay (30V coil instead of 12V coil might make that difference).

When I put my volt meter to +12V and then to the base of the transistor, I see that there is 16.7V. This does not make sense to me.

The base of the transistor that controls the non-working relay shows 14.4V.

The traces leading to these transistors come directly from the large micro controller. "

All that sounds like you are shooting a canon in a dark room.

What are the chances that I fried the controller?
Not Zero

Jona Listen,
fixing stuff is working gradually and logically.
measuring and finding the fault and then replacing the faulty part,and just that one alone!

Care to start from the begging?
and if you feel bored... take-five and don't touch


So, you don't have the schematics.
Let's try to create one the best we can:
Please take some good photos of all the parts (including motors.transformers,boards etc. ) and try to make sense of what is connected to what.
We can try to work this out with you.
Then we can do some measurements and continue.

 

[Jonawald]

Jona Listen,
fixing stuff is working gradually and logically.
measuring and finding the fault and then replacing the faulty part,and just that one alone!

Care to start from the begging?
and if you feel bored... take-five and don't touch


So, you don't have the schematics.
Let's try to create one the best we can:
Please take some good photos of all the parts (including motors.transformers,boards etc. ) and try to make sense of what is connected to what.
We can try to work this out with you.
Then we can do some measurements and continue.[/QUOTE]

Hi Dorke. I am with you. I have been working slowly over the last three weeks. Circuit by circuit I have been learning what each of the components does and is supposed to do. I started this project with very little knowledge of how electronics worked. I feel I know more now than I did two weeks ago. I also know that there is a lot to learn yet. Shooting a Cannon in a dark Room. Ya that's what I feel like. It's a huge project to take on with the limited knowledge I have.

What I need is a good guide who can help me through this.

Take a break sometime. Yes. I have been working non-stop for way too long on this. Weeks already. I decided to take a break this evening and do nothing. then I slipped in and checked for replies.

Tomorrow, I will take pictures. Lots of them and post.

Jonathan

 

[Jonawald]

Ok, Today. I am going to post pictures of the boards and the chairs as they are right now. will try to include as much detail as possible to help this process along. The first there pictures are of the chair itself. The first is obvious. the second is the "Heat unit" Not sure what it does but it has a power lead and a sensor lead that goes to CN33 on the board.

The third picture is underneath the chair. It shows the various wires, and at the far end the air pump and solenoids that control the air bags.

 

[Jonawald]

Here are overview pictures of the front of the boards. I will attempt to open them in an editing program and label each of the components to make it easier to see what's going on. I will also post pictures of the backs. The smaller board is for audio. There is another small box with a USB port for loading MP3s. I have not tested this board. I have replaced all the visibly bad components on this board. I replaced all the caps and a lot of the resistors. I pulled and individually tested the transistors and replaced the 78l08 regulator with a brand new one the original leads were rusted off.

 

[Jonawald]

Ok. I got a few more good closeup pictures before the battery of the camera ran out.

 

[dorke]

Hi Jona Welcome back.
Nice looking chair.
and a jungle of wires underneath.
Is there a manufacture name and product model?

In you first post you say you fixed 2 other chairs.
Do you still have them?
They can be used as a precious reference to a working unit,
that can make life a lot simpler.

A lot of quit bad water corrosion signs.
The print side is also important,can you please post some photos?

I understand you already replaced parts.
Can you please show a pic of your soldering?

I think a good place to start is with the mains board.
Can you show/explain how the motors/transformers etc. are connected to it?
Any parts replaced on that board?

I marked some things to check on the board.
The fuse is corroded needs cleaning/replacement.

 

[Jonawald]

Hi again. I have one of the chairs that I already repaired. It is nowhere close to as complicated as this one. It has only five air bags, their air pump relay and a recline/restore relay set. It was a perfect starting point for me just easy enough to figure out. The other one was very similar to this one but I don't have it anymore. I returned it to the owner after cleaning the board and replacing a fuse. I got lucky on that one.

On to your questions. I will be posting pictures of the print side of the board in a few minutes. The brand is Cozzia. The model number sticker is gone from the chair.

The mains board, pictured has been almost completely rebuilt. The left side in the picture with the transistors, resistors and optocouplers have all ben replaced. I ordered the optocouplers from digikey.com. The transistors are mostly used ones I pulled form other boards and tested to make sure they were the same as the original and working. Somewhere in the course of this I built a transistor testerhttp://www.instructables.com/id/Transistor-Tester/ that is able to test the four different type son transistors and tell me what type they are. Most of the components on this row were badly damaged. I can show pictures from before if that would help.

Yes Mains go where you checked. I know that the fuse needs to be cleaned up but I was ignoring it because it was working and there were more pressing problems than this one. The question on the bottom left is a jumper that was replaced. The resistor not neatly placed was one of the first I soldered in before I learned how to properly bend the leads so that they would sit snug.

 

[Jonawald]

Ok with camera back in action. I took pictures off the back of the mains board. My jumpers may look a little crude... I guess that's because they are. I probably need more practice/instruction on proper soldering methods. Tell me what you see and what I need to improve. I ready to listen.

Ok with camera back in action. I took pictures off the back of the mains board. My jumpers may look a little crude... I guess that's because they are. I probably need more practice/instruction on proper soldering methods. Tell me what you see and what I need to improve. I ready to listen.

 

[dorke]

Cozzia, that's a start.
You can contact them an inquire about a service manual.
A bit difficult without the model number but a photo of the chair and remote may do the trick here

 

[dorke]

I probably need more practice/instruction on proper soldering methods. Tell me what you see and what I need to improve. I ready to
listen.

Wow,
That's an understatement
Jona ,
I see a total mess '
I'm afraid you have to "repair the repair",all of it,that bad.
Please show the soldering Iron you use.

Look here for a good old soldering video

 

[Jonawald]

Wow,
That's an understatement
Jona ,
I see a total mess '
I'm afraid you have to "repair the repair",all of it,that bad.
Please show the soldering Iron you use.

The soldering Iron I use now is not the one I started out with. I got a new one on Monday. It has digital temperature settings. I left them on default because I was not sure what temperature would be best. I also have a Deluxe Soldapullt desoldering tool that I modified by adding two extra o-Rings so that it actually sucks.

 

[Jonawald]

A lot of the mess you see though is blistering of the green finish on the board. It was a total mess after having been left dirty after the flood. Probably some blistering also happened when I heated with my iron. I had to do a lot of cleaning and scrubbing. Also, I think somebody tried putting power to the board in its dirty state before I got a hold of it. There were already some traces melted off from short circuiting.

Also, All those circuits you see were working perfectly before my accident with the soldering iron when the thing was under power. I made sure there were no extra connections and that everything made contact to the board before powering anything up.

 

[Jonawald]

Cozzia, that's a start.
You can contact them an inquire about a service manual.
A bit difficult without the model number but a photo of the chair and remote may do the trick here

I have tried contacting them in the past regarding an entirely new board. Never got a response. I put in a new service request asking for a service manual just now.

 

[Jonawald]

I added some notes on these two pictures.

 

[dorke]

The soldering Iron I use now is not the one I started out with. I got a new one on Monday. It has digital temperature settings. I left them on default because I was not sure what temperature would be best. I also have a Deluxe Soldapullt desoldering tool that I modified by adding two extra o-Rings so that it actually sucks. View attachment 23927

That is a good solder iron.
Please show the solder wire.
Don't use the sucker,it makes more damage than good,
instead use a solder wick 0.1" or so.

Please watch the video above and learn how to solder,
then practice on some junk board( desoldering and soldering).
when you think you can do a good job show it ,before that don't try it on the chair boards.
We can go on investigating the boards ,no problems,but no soldering yet.

 

[Martaine2005]

@HellasTechn
https://www.electronicspoint.com/threads/pcb-building.273651/

 

[dorke]

I added some notes on these two pictures. View attachment 23930View attachment 23931

Jona,
Please see the videos.
Only then we can discuss what is wrong...

For now
,I'll just say that you should have used
a "solid single wire" for bridging.

 

[Jonawald]

I was seriously considering replacing that before taking the pictures. Then decide to just show it as it is and take the hit.


I will watch the video and do my due diligence with practicing .

I have wick, but it never seemed to work for me. The sucker was much quicker and cleaned up really nicely. Care to elaborate just how it does damage? Just so that I know.

In the mean time, if you have things to test on the board or an area that you need better pictures of let me know. I will try to watch this thread closely all day.

 

[dorke]

It is a series of videos ,take your time watch them and learn, they are very good professional ones.

The pump suckers may suck the solder with the Pad.
I have seen that many times ,especially if the PCB quality isn't very good.
If you know how to use the wick it is safer an cleaner.

What did you solder that caused the unit to stop working?
Can you show it on the board?

and please show the way the motors are connected to the boards.

 

[Jonawald]

Here are two pictures annotated with the information you are looking for. Let me know if I missed something. Massage motors out should read Vibrate instead of Massage.