Conference hydra::amiga_v1

    I had the same problem with my 1081 recently. Turned out to be "a bad
    connection on a HT lead", repairers words not mine.

    Could also be a bad T402 (big muthur Xformer).  If is happens after
    you have had it turned on for awhile and if it doesn't seem to be
    a loose connection anywhere, then probably it is a T402.  Are you
    also experiancing "flashing"?  Finally, what is the manufacture
    date and serial number of the unit.  Could be a nasty phillips
    manufactured transformer and associated motherboard upgrades.  Let
    me know and I'll tell you if you have a problem with your monitor.
    
    TOPGUN

    I don't quite understand... Tapping sometimes seems to help...
    Now its up for appx 15 minutes and then blank screen. Must
    be thermal. If thermal where is the best place to look? I'll
    get a good can of freon and test.
    
    M. Gaines

    I found the problem, its up and running. I put pressure on the flyback
    or the main board and the screen would return. Looks like a stress
    related failure. put pressure between the flyback and transistor
    heat sinkand no more problem.
    
    M. Gaines
    
    

    I didn't want to create a new topic so here it is :
    
    ************************************************************************
    
    I've got my amiga & 1084 since 3 years and here are the two problems:
    
    	- On the whole right side of the screen, the white turns to light
    	  pink (I had this for quite sometime). Someone told me it is a
    	  de-magnetization thing. (This doesn't worry me to much)
    
    	- What worries me, is that :
    	  I think the display get's smaller & smaller. There is a button
    	  on the back to change the horizontal lenght of the screen. When
    	  I got the screen, I could enlarge it, in such a way that the
    	  screen looked huge, i had to get a small display (horizontaly)
    	  to see the whole display.
    	  Now the button is at his largest display possibility and I've
    	  got now � inch on each side of the display, that are not used by
    	  the computer. What can I do ? (If somebody understands the
    	  problem ;-).
    
    								Erik

	It sounds like the high voltage power supply is slowly wandering south.
This is a fairly common failure mechanism in monitors. The fix is to replace the
HV supply. If you're not used to dealing with lightning bolts, have a trained
professional handle it.

    Normally if the high voltage is decreasing the picture tends to become
    larger and not smaller... Nevertheless sounds like the monitor HW is the
    Problem.
    
    Ernst

	You're right. I just looked up the equations. 

	Sin(theta) = 0.3*HL/SQRT(Eb)

	My workstation monitor shrank like that twice and field service
fixed it by replacing the HV supply. It must have been supplying the power
for the magnetics, too.

    I just want to add here my experience with a simular problem. My 1084
    monitor screen went black after 15 minutes. Tapping on the monitor did
    get the picture back again for a while. 
    
    I had the same problem 2 years ago with the monitor of a friend of
    mine. 
    
    The cure:
    
    resolder the leads of the High voltage flyback transformer. This worked
    in both cases. I assume that the leads of the transformer were not
    completely clean when the transformer was inserted in the production
    proces. Causing bad solder joints, resulting in thermal sensitive
    solder joints. 
    
    Jos van Loendersloot

    Hi,
    
    I got the same problem too: After a while the picture clicks. Then the
    screen went totally black. You got it back, by tapping on the monitor.
    Later you really had to hit him, to get the picture back.
    
    So I brought it to a service station. The guy there later said, he had
    resoldered nearly all soldering points on the board. Since then the
    monitor works perfect. This is a bad and cheap construction! If you
    have this problem too, you should fix this by yourself only if you are
    familar with such things. Else the monitor probably won't do anything
    afterwards.
    
        Tobias.
    

    MY 1084 is starting to act up when I first power it on. Then it levels
    out fine. I am upgrading to a 1084s.
    								bill

    re. .10
    
    > I got the same problem too: After a while the picture clicks. Then the
    > screen went totally black. You got it back, by tapping on the monitor.
    > Later you really had to hit him, to get the picture back.
    
    Me too. I found an article in Amazing Computing that discusses this
    exact problem. Apparently it occurs on 1080's, 1084's (but not 1084S's)
    and 2002 monitors. Mine was a 2002. The red wire from the high voltage
    transformer to the tube runs past an L-shaped heat sink in the back
    right corner (looking from the back). This heat sink charges up like
    a capacitor from the high voltage. It is held to the board with 2
    screws and a metal twist tab. The twist tab is within a hairs breadth
    of a ground run on the board. The heat sink arcs across here to
    discharge. With time a carbon trace builds up making the distance to
    ground shorter and the arcs occur more frequently. The 2 screws are
    enough to hold the heat sink. I broke off the twist tab and put some
    shrink wrap and tape around the high voltage line and it fixed the
    problem. The article also suggested spraying some plastic around the
    high voltage transformer and applying TV dope to the ground run but I
    didn't bother. I can remember which Amazing Computing it was in. I'll
    look when I get home.
    
    Tom

Hi,

	I had this problem with my Philips 8833, (the same monitor which is 
	inside the CBM casings as 1084/S). I had it serviced, and was told
	that it was a problem with the transformer voltage, as you have said,
	I think a dry joint was causing the problem.

								- JIM CAD*