A4000 video problems

A4000 video problems

Post by Cliff Wakefie » Fri, 09 Dec 1994 09:22:24



Hi,
        I am the proud owner of a A4000/EC030(love an '040 though) anyway
the machine has been working fine since i bought it.   Recently I went to
a local computer meeting and took my trusty 4000 with me.  Upon my return
and resetting up my amiga i noticed a problem withe video signal.   I own
a NEC 3D multisync monitor so the picture is really clear and crisp and
I noticed that the brightness of the display was flickering randomly, not
all the time but enough to be annoying.    At first I suspected the
monitor to be at fault thinking I had somehow damaged it in
transportation, but alas after trying a 1084 on the 4000 the problem was
still apparent.
        I opened up the amiga to check out the video chips and port,
making sure that the cabling and ports on the back were okay to no avail
no amount of wiggling would alter the random flickering of the luminance
signal.   In the old days sometimes problems like these could have been
rectified by resetting the chips, but as any AGA owner will now commodore
in there great wisdom made the custom chips all surface mount.   Next I
tried tapping and gently flexing the general area of the video port and
video chips this in no way affected the flickering neither diminishing or
increasing the problem.
        So am at a lose as to what has happened I would have suspected
that my moving the motherboard would have increased the problem if it was
physical one, but it seems that the problem is actually caused by the
chips themselves.   I'm not altogether sure which chips are responsible
for the graphics in an AGA machine.   And due to the current commodore
situtaion I can't take the machine in for service.  
        I was wondering if anyone had an suggestions or things to try in
order to rectify or identify this problem.   Or has anyone else had this
same problem?
        Also I have been told that even if I was to install a graphics
card in my machine at a later date that the card feeds its luminance
signal off of the motherboard which of course would transfer this problem
across.   True or false?
        The machine is useable as i'm using it to type this at the mo,
but the flickering is very annoying, the luminance signal jumps up and
down and my display has lost its brightness so everything seems dim, even
with full contrast on the monitor.

        Hopefully someone will be able to help me thankyou for reading this.

-- Cliff

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Amiga 4000/EC30/10/330/NEC 3D - Amiga owner till death do us part.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 
 
 

1. A4000 Video Problem. Please help!!!

My Amiga 4000 video seems to have gone kaput.  The screen went blank
sometime back.  I first suspected a defective 9-pin female RGB port;
therefore, I bought a one and replaced it.  When this didn't
produce a non-blank screen, I suspected a faulty 1084S monitor,
and I bought a used 1080.  Still, no dice!

Up to that point I hadn't considered that my A4000 (bought in summer
'93) could be having a video problem.  I dug out my old A2000 and tested
it with both monitors.  Both monitors started up normally.  Therefore,
clearly the monitors and their cables, as well as the new RGB port, are
all fine.

Furthermore, I placed a WorkBench 3.0 Program disk in the A4000's internal
floppy drive and rebooted to see if the system would load from the floppy.
I was essentially checking to see whether the problem was localized to the
video section or whether the entire mother board was defective.  The
floppy's LED light flashed on and off as it should during a sucessful
boot.

Consequently, it seems clear that I have a video problem with my surface
mounted A4000 motherboard!!! for a computer for which manufacturer has not
been producing any motherboards for months!

Does ANYONE has any idea about anyything I might be able to do AT ALL!?!
short of shopping for a used motherboard?
--

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