# Sony DVD/VCR Not receiving remote signals, some onboard buttons not working



## Jackovarian (Sep 28, 2010)

Hi guys, 

I'm hoping someone could point me towards the right area on the logic board to look for the problem.

The remote is working fine. Checked it for output using a camera and also set the tv function to control my tv.

The DVD/VCR's IR sensor is receiving power fine, so are the set of buttons that arent working. They are also operating perfectly as switches. 
I have checked the voltages running across each and then broken the connection by pressing the button, yadda yadda.

So basically I've traced the boards back to a connection to the logic board. All connected fine. The problem is that their interrupt signals aren't being received or read by whatever the controller is. 

Problems on the logic board. Some of the buttons work fine. Some dont. 

I assume its some kind of electrical stroke situation. But I'm lost at sea when it comes to the logic board of a DVD/VCR. 

What should I keep an eye out for? What would cause some buttons to work and others not? 

PLEASE HELP!!!!!!!


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## octaneman (May 13, 2009)

Hi Jackovarian.



The buttons traces on the logic board go through an controller I.C, the board itself could be bolted on to the button panel, or on a 2 layer PCB connected to a surface mount 80 pin SQFP package type processor. This package type has pins that are so fine you will need a jewelers lens to see them. You will need a schematic of your DVD player and an oscilloscope to probe the interrupt signals to diagnose the problem. Signal analysis requires a scope a DVOM just won't cut it, what you can do with the DVOM is probe the 5 volt regulator that supplies the voltage to the receiving end of the I.R LED and see if the regulator is doing its job. 



Good Luck !


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## Jackovarian (Sep 28, 2010)

Thanks very much for your reply.

Well unfortunately I dont have access to a oscilliscope here...
But I managed to trace all connections back to an I.C. just like you said. 
Beside one corner of the I.C., the board is raised in a bubble. The metal leaf has come off the plastic board. Seems solid enough however. So i'm unsure if its from heat, age or manufacture. 
All connections in this area seem fine. But i would imagine that the breaks, if they are there, are so minute as to be re-connected by the slightest touch. 

I really dont have much sensitive equipment here bar the DVOM. So i'm going to try soldering each little leg a bit. Without solder, just to see if it will reconnect it enough to test. 

Then again, if it is multiple layer PCB chances are its unsalvageable. That bubble could have damaged any of the lower layers.


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## Jackovarian (Sep 28, 2010)

Oh and I've searched for a service manual, repair manual and schematic but to no avail. Its an old model.

Sony DAV D150G


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## octaneman (May 13, 2009)

Where the bubble has formed if there is a brownish discoloration on the surface area it means that is heat damaged. Since the copper plate has peeled off it's a sure bet that the connections have been broken, and it will be extremely difficult to repair it without solder. Depending on package type if you are going to attempt soldering the I.C , make sure the tip of your solder is curved at 45° angle and use flux. There are other alternatives you can try like a trace pen, solder paste, heat gun, whatever method you decide to choose there is that possibility that board is too far gone to repair. 


Note: Here's a web site I use for all my schematics, you won't be disappointed. 

https://www.manualsparadise.com/AboutOurStore.do;jsessionid=412DF38B9CB00AE2F25D796C7A0F904F 

Good Luck !


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## Jackovarian (Sep 28, 2010)

I have checked all the legs and they are now connected correctly...

Still nothing. 

There is slight brown discolouration in that bubble. But I can see that its single layer PCB. 

All connections that run through that bubble area are OK. The strange thing is, the bubble is at a point where there is nothing on the board but power lines. It is beside the chip though. 



So... What could it be? Maybe the chip is heat damaged?

I have no way of checking the functionality of the chip. 

I'm completely baffled now.


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## Jackovarian (Sep 28, 2010)

Thanks for your excellent reply by the way


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## Jackovarian (Sep 28, 2010)

I just tested the machine with a tv, I've gained semi functionality with one button. 
Also, the machine seems slightly scrambled because when it turns on it throws up a menu of letters. Which is kind of strange. This button does the same after i've managed to clear the screen.

Not much information towards the actual problem. But at least I know I'm looking at the right area. 

Seeing as I dont have the proper facilities to do a good job, I might run some coated wires from the IC to their respective connections, bypassing the bubble.


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## octaneman (May 13, 2009)

Please post a series of pictures of your PCB where the area is most damaged so a more indepth analysis can be done.


All DVD's when starting up take their info from the firmware chip, the I.C's function is identical to what a bios chip does for a computer. Any interruption of the software while on start up will mess up the functionality of the player. You did mentioned that all legs are connected to the board but the question remains, are the pins getting the proper input/output voltages or grounds ? You also said that random letters appear on the screen, this means that the video signal is still intact but no other resource is accessed ( IE: screen buttons or remote). This will be a painstaking process because you will need to know which buttons get power while switching them on/off, to do this you will need your DVOM to probe each pin from the processor to the switch. By doing a continuity test you can isolate which traces are good and which one's are giving an intermittent signal. Keep in mind that the remote also has it's own IC on the main board. 

Note; Take the number off the IC and find out what it does, also use a magnifying glass to follow the traces, make a diagram to where they go on the IC and to which pin. With a little persistence you'll be able to isolate the fault.


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## Jackovarian (Sep 28, 2010)

I wont be able to post pictures until next week unfortunately.

I will try your method. But it will be difficult because the chip is on the underside of the board, facing the bottom plate of the dvd player chassis. Also, it has a VCR section that slots down onto the board from above. Might be able to side mount it though and keep all the cables connected. 

I'll post my findings next week.

Thanks for all your help Octaneman!


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## Jackovarian (Sep 28, 2010)

Hi!,

I never got a chance to post the pictures last week, been busy. 

But I did manage to get some background information on the issue and when it may have started. 

What I found out is that the machine has always been like this (From the second owner, the first owner had this less than a year). The remote and buttons never worked. 
This sounds highly suspect to me as I'm sure the original buyer would have returned the faulty item. 
(I bought this third hand, thinking the remote was broken)

So now I'm pretty sure its not the chip. At least not initially. I have a sneaking suspicion that the machine may have been dropped on the floor as that seems the most realistic source of the failure.

There is no signs of liquid damage and all internal fuses are intact and look to be the oringinals. 

So now I dont know what to look for or where to look. I've tried a few of the smc resistors and caps in the immediate area of that chip, but they all seem to be OK. 

I cant obviously check the oscillating crystals as I've no equipment. Seeing as the remote signals aren't being read i'm thinking they may have something to do with all this. 

I'm really stumped, particularly so because this goes far beyond my area of expertise! 
(I study electronics in college, 2nd Year)

So if anyone has any ideas or hunches, please, I'll try anything at this stage!


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## octaneman (May 13, 2009)

Jack


If you do suspect that the player has been dropped you will need to look for broken traces and solder joints. Pick up a jewelers lens that will magnify 10x it will be 100x better than just eyeballing it. Identifying broken joints use a heat gun or hair dryer on the board as its working, if there is a cold joint the heat will help you identify a possible location, also look for heat discoloration on the board this will tell you if anything is overheating. Another good thing to have is cold spray, if you suspect a component that's overheating apply cold spray on it and the circuit will wake up temporarily until its replaced. 


Having fancy scope equipment is only a small part of your diagnostic equipment, almost 99% of intermittent circuit faults are caused by cold solder joints, the real trick is having the patience to look for them. When faced with problems like this in allot of cases you will have to re-solder all the joints one-by-one.


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