NationalVCR NVG7A Service manual & circuit and data shee

nerang@ki · Joined: 23 Jan 2006 Posts: 1

I desparately need to find the circuit ,data sheets and any service manual for this trusty old warrior of a VCR.
On / off / eject red and green LED' not lighting up now. Test out OK with multi- meter and each of the three fuses are fine.

Something is suddenly sick.
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Arthur&Son

gary · Joined: 05 Apr 2005 Posts: 584 Location: MANCHESTER, uk

TRY REPLACING THE STK PSU IC, COMMON FAULT IS LOSS OF ONE OF THE SUPPLY RAILS FROM THE IC, ON SET THIS OLD WOULD ALSO B WORTH REPLACING ALL ELECTROLYTIC CAPS IN PSU WHILE IT IS IN BITS.

nerank@ki · Guest

Thanks Gary for the suggestions.
I removed the psu unit and it tests OK.
So I'm a bit lost without a circuit to explore what other possibilities need exploring.
Any manual / datasheet / circuit for the NationalVCR NVG7A would be very useful as the tuner in this old VCR always gave a very strong signal.
( Much better than many of the newer ones available ) particularly as main digital terrestrial signal often drops out.

gary · Joined: 05 Apr 2005 Posts: 584 Location: MANCHESTER, uk

the psu needs to be tested while connected to the vcr as the supply rails will often only be low while under load, it is best to check the supply rails on the secondary with an oscilloscope as this will show which rails are incorrectly smoothed with hf ripple, DO NOT rely on a multimeter with this fault.