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Author Topic: Cracked circuit board repair  (Read 3706 times)

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Offline Cozzmo

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Cracked circuit board repair
« on: November 12, 2013, 06:49:57 am »
Hi all.

I have a DVDR/VHS combo unit here that failed the Australia Post test (long story...) It still powers up and plays a DVD fine, but upon trying to straighten out the Aerial inputs, i realised they weren't just sockets on the rear panel and were directly attached to the tuner module.

The Tuner module (p/n ENGF7704KF) was damaged and its cracked the circuit board in two places. The Unit is a Panasonic DMR-EZ47V.

Being that these traces are running to the tuner, do i need to do anything special with the wiring other than keeping it short? I don't think i can fix/band aid each of the traces where they are cracked (twice), i would need to trace them to a pad and jump wire them which should be doable. Thankfully its a single sided board so where the pads have ripped off the board a little on the pins i was able to save them mostly intact. Only had 2 come off and i don't think they are actually connected to anything (service/wiring diagram wouldn't hurt to confirm!).

Also would a tuner module part like that be available as a separate item ? Or would it be not worth while? Otherwise the unit is in immaculate condition.
 

Offline ludzinc

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Re: Cracked circuit board repair
« Reply #1 on: November 12, 2013, 07:05:54 am »
Quick question - being a VHS device does it have a digital tuner?

If not, is there any point repairing (analogue TV being switched off in most - if not all? - parts of Oz now)?
 

Offline Cozzmo

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Re: Cracked circuit board repair
« Reply #2 on: November 12, 2013, 07:14:59 am »
Yes this model does have a digital tuner, but does SD channels only.
 

Offline nanofrog

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Re: Cracked circuit board repair
« Reply #3 on: November 12, 2013, 09:24:54 am »
You'd want to get epoxy into the crack and under any lifted traces. Add mechanical support if possible in the cracked area, such as along an edge using a bit of unclad PCB material (I.e. epoxied perpendicular to the crack).

Traces could be damaged in the process if they aren't already (easy to check via continuity), so have a look at this video to see ways to go about trace repair should you need to (shows how to do the method you're interested in using).

PACE Rework and Repair of Electronics Lesson 6 - "Damage Repair"

Hope this helps.  :)
 

Offline amyk

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Re: Cracked circuit board repair
« Reply #4 on: November 12, 2013, 11:34:16 am »
Good that it's single-sided; all you need to do is wire over the broken parts.

How much damage did it cause to the tuner? If it's just the sockets then you can replace those easily.
 

Offline Terabyte2007

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Re: Cracked circuit board repair
« Reply #5 on: November 12, 2013, 12:20:02 pm »
Since that is a single-sided board it should be fairly easy. I have repaired these in the past by removing the solder mask gently, using epoxy to repair crack (on opposite side) in the board. Clean with a flux pen, then solder drag a few bridges across the cracks and check with a microscope, test then use a clear enamel coating such as a nail hardener much as what your wife or girlfriend would use on their nails. Brush this over lightly to seal and protect and you should be good to go.

Here is a reference for solder mask removal.

http://www.circuitmedic.com/features/514.shtml

Eric Haney, MCSE, EE, DMC-D
Electronics Designer, Prototype Builder
 

Offline Cozzmo

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Re: Cracked circuit board repair
« Reply #6 on: November 13, 2013, 07:05:35 am »
Thanks for the info and the links guys. All very helpful.

The sockets i thought would be easier to replace but they look to be spot welded to the casing of the tuner module, so not as easy as i had thought to replace them. I figured sourcing a replacement tuner module might be easier, but could be expensive and not worth it in the end. I might just have to run a short flylead to the board to replace the sockets.
 


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