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41 volts in my DVD's AV output jack ground.

tedstruk

Jan 7, 2012
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OK. The buttons are fine also.
So are there any procedures for testing a board for faults? or opens as the case may be?
How do I test the thing? I mean a guy can't take out each individual component and replace it and find out whats wrong without replacing everything!!
 

tedstruk

Jan 7, 2012
476
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I Got the AV PCB out!!! rah ha ha ha ! the AV PCB is out!...the Mains PCB was easy too.



IMG data. you are looking at the front of the machine, the 3 AV inputs and S-vid input and the control board. Away from you is the rear.

What should I test first?
 

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tedstruk

Jan 7, 2012
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The induction coils are sending my 2vpp osc signal back perfect on one set of coils and showing a loss of about 1v on the other set.
 

Gryd3

Jun 25, 2014
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OK. The buttons are fine also.
So are there any procedures for testing a board for faults? or opens as the case may be?
How do I test the thing? I mean a guy can't take out each individual component and replace it and find out whats wrong without replacing everything!!
You are absolutely right!
Pulling things one by one and testing / replacing is both time consuming and expensive.

In an ideal world, you would have a schematic of the circuit board which but the best you can do without one is looking at the board and trying to trace the lines.

If you are measuring resistance, you must know what other components are connected to the device you measure. You mention one coil acts differently than the other, but if you trace the copper lines and the jumpers around you will most likely find that one coil is connected to different components.

For me, initial step is always inspection of the board looking for obvious faults or damage.
If none can be found, I power the board up and use a voltage meter to poke and prob around.
The problem here of course is that there is the potential for lethal voltages when working on mains powered equipment... if you can locate or find enough information on the board, you can sometimes power it with your own 'isolated' low voltage power supply. If not, I would strongly suggest using an isolation transformer.
Once powered, initial step would be to locate and test the output of any voltage regulators, followed by ensuring power is present on the ICs of the board. (Check the data-sheets to ensure which pins are for power)
The schematic here is really useful... it's not uncommon for ICs and portions of the board to be disabled or turned off by another portion of the circuit while in stand-by mode for example... If you find a chip that has no power, begin tracing the copper traces to determine what component may be powering it.

It's time consuming... but in this way you slowly make your way across the board starting with power.
When you begin tracing lines, it's more of a logic level of inspection to find out why something isn't powered when it should be... Datasheets here are your friend... You may find an IC that is responsible for testing the voltage level of multiple supplies and if they are not perfect enough it may not power on the rest of the board.

Anyway... short-form of first steps.
Inspection, then power it up safely and test for power.
It's always a good idea to have someone else present while you work on anything live.
 

tedstruk

Jan 7, 2012
476
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then everyone chickened out...
I think residual voltages are cool, they remind me of my humilities....
 
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