Circuit Board Repair?

[Biggles]

Hive Wisdom Sought.

 

This is the circuit board from a Dometic RMD8555 3 way fridge.  The fridge packed up and I got to hear of a company called Get It Fixed.  I contacted them and they said they had experience of this board and on sending it in the diagnosed this chip needed replacing.  I paid and a couple of weeks later its arrived back.  

 

I'm not an expert in electronics.  This chip looks exactly the same as before and there seems to ne no evidence that the chip has been changed.  I have seen these changed on YouTube and a heat gun is used to do the soldering, but there is no evidence either on the front or the back of the board to suggest its been changed.

 

Before I remount the board I wanted opinion, as I suspect they have done nothing and will go on to say I have damaged the board when connecting it up.

Thoughts please 

[robtheplod]

I suspect you're going to have to fit it to see if works aren't you?  No point having a go at them if they have repaired it ok?

[Biggles]

Yes I get that, but a little expert comment would be valuable.  Do you have anything from an expert POV to say?

[alan_fincher]

I'm not up to speed on modern day repairs of PCBs, but did used for a while to do it as a day job back in the mid 1970s.

 

I find it hard to believe that that chip has been manually de-soldered, removed and replaced to show so little evidence of such an operation.  There is no evidence of flux left around, for example.

Is it possible that what they have actually done is to simply send you a complete board that they held in stock?  Can you conclusively say that the board you have got is the one you sent them.

[jake_crew]

FWIW the close up of the chip shows untidy soldering to me.

 

So perhaps they have done something.

[MtB]

Once it arrived, they may have traced the fault to something else and fixed that instead. 
 

Or…

 

Are you certain this is the board you sent them? They might well have sent u a different, repaired board. 
 

[IanD]

That does look like a chip that's been manually (re)soldered to me, but it's difficult to be sure. There's normally no added flux used when reworking a QFP (Quad Flat Pack) package like this, it drops onto the solder already on the PCB pads.

Edited March 3, 2023 by IanD

[robtheplod]

1 hour ago, Biggles said:

Yes I get that, but a little expert comment would be valuable.  Do you have anything from an expert POV to say?

oops sorry no, I'm not an expert....

[GUMPY]

Soldering if redone properly can't be seen by an amateur to have been done.

It may also not be your original board but an exchange board they will then fix yours at leisure and someone else will get it 

Fit it and find out if it works😱

[Higgs]

1 hour ago, Biggles said:

Yes I get that, but a little expert comment would be valuable.  Do you have anything from an expert POV to say?

 

There maybe nothing wrong with the chip, and may have been put in an oven to reflow the solder. It may have had a few dry joints. It can also be done with an hot air gun. 

 

 

[cuthound]

I visited the Deep Sea factory once. On their repair line they put PCB's into an oven and used a vacuum to remove the solder, before replacing any faulty components and dipping the lower part of the board into a bath of molten solder. 

 

This left no evidence of a manual repair.

[IanD]

18 minutes ago, cuthound said:

I visited the Deep Sea factory once. On their repair line they put PCB's into an oven and used a vacuum to remove the solder, before replacing any faulty components and dipping the lower part of the board into a bath of molten solder. 

 

This left no evidence of a manual repair.

 

This can be done sometimes if all the components on the PCB can be reflowed, but often a finished PCB has had other things added in final assembly which don't allow this.

 

Reworking a small QFP like this is actually quite easy to do by hand given the right tools, without disturbing anything else on the PCB.

 

A BGA (Ball Grid Array) with >1000 pins is rather more difficult, but can still be done if you *really* know what you're doing... 😉

[Bee]

You should have let me have a go at it - you'd soon see the difference.

[Jen-in-Wellies]

I have been involved with this sort of repair more recently. A skilled person can replace a component like that and leave no evidence that it has been done. That you can't tell, either shows they haven't done it, or they have done it and are very good at their job. See if it works!

[MtB]

31 minutes ago, Jen-in-Wellies said:

I have been involved with this sort of repair more recently. A skilled person can replace a component like that and leave no evidence that it has been done. That you can't tell, either shows they haven't done it, or they have done it and are very good at their job. See if it works!

 

If I'd done it using my old Antex smouldering iron there would be plenty of evidence it had been done, AND it probably still wouldn't work...

 

 

[GUMPY]

15 minutes ago, MtB said:

 

If I'd done it using my old Antex smouldering iron there would be plenty of evidence it had been done, AND it probably still wouldn't work...

 

 

You would have used an Antex and not a blow torch ?

[MtB]

25 minutes ago, Loddon said:

You would have used an Antex and not a blow torch ?

 

I'd warm it up with the blowtorch, obviously.

 

 

[magnetman]

perhaps worth applying some sort of indelible invisible mark somewhere to identify the board. Drill a very tiny hole somewhere or something.

 

Are they reserving the right to send you an exchange or are you paying for a repair to your own board? 

 

[GUMPY]

28 minutes ago, magnetman said:

perhaps worth applying some sort of indelible invisible mark somewhere to identify the board. Drill a very tiny hole somewhere or something.

 

Are they reserving the right to send you an exchange or are you paying for a repair to your own board? 

 

I wouldn't care so long as the board worked🥴

[blackrose]

22 hours ago, Loddon said:

Fit it and find out if it works

 

Yes, and if it works then this thread was unnecessary. I can't see the point of all the speculation - just get on with it and fit the board. If it doesn't work then there's a different conversation to have with the repairer 

[booke23]

On 03/03/2023 at 15:00, Biggles said:

Hive Wisdom Sought.

 

This is the circuit board from a Dometic RMD8555 3 way fridge.  The fridge packed up and I got to hear of a company called Get It Fixed.  I contacted them and they said they had experience of this board and on sending it in the diagnosed this chip needed replacing.  I paid and a couple of weeks later its arrived back.  

 

I'm not an expert in electronics.  This chip looks exactly the same as before and there seems to ne no evidence that the chip has been changed.  I have seen these changed on YouTube and a heat gun is used to do the soldering, but there is no evidence either on the front or the back of the board to suggest its been changed.

 

Before I remount the board I wanted opinion, as I suspect they have done nothing and will go on to say I have damaged the board when connecting it up.

Thoughts please 

 

In the distant past I used to work in electronics manufacture and I spent a bit of time in the faults and rework department.......where this sort of repair (and much more complex BGA repairs) would be undertaken on boards that had just come off the line, which for whatever reason, would occasionally need remedial work. 

 

I agree with what others have said.....ie done properly with the correct equipment you cannot spot this sort of repair. On the left side of the chip a few of the legs show signs of rough but probably perfectly functional soldering. I think you need to plug it in.

Edited March 4, 2023 by booke23

[Onewheeler]

Looks like a solder bridge (or spatter) top left of lower picture. Doesn't look original anyway.

[StephenA]

Re flowing the solder (usually fluxless) on QFPs is pretty common practice... Just about anyone with a turn of the Millennia Volvo (S60 etc) has had this done on their dash module at least once, and there is no sign on the reflowed boards that anything has been done.

[magnetman]

59 minutes ago, Onewheeler said:

Looks like a solder bridge (or spatter) top left of lower picture. Doesn't look original anyway.

I don't do any of this sort of thing but first impression was that this looked a bit naughty

 

[robtheplod]

7 hours ago, Jen-in-Wellies said:

I have been involved with this sort of repair more recently. A skilled person can replace a component like that and leave no evidence that it has been done. That you can't tell, either shows they haven't done it, or they have done it and are very good at their job. See if it works!

Ah, vindicated, thanks Jen!