Conference 7.286::atarist

Well, I personally don't know, but I did manage to dig up the following
from the archives of our NASTUS newsletter articles:

  Fixing your Mono Monitor
  ------------------------
  In article <[email protected]> [email protected] (holly) writes:
 
   >Greg Thompson's mono monitor went *snap* and died...
   
  >We've seen three mono monitors in the last 2 months come into our store
  >with a blown capacitor. 
  >Sometimes the video just shows a line, sometimes it's black when it happens.
  >Was the green power light still on on the front?
  
  >Anyway, if it's that same problem, it is fixable.  You might try taking it
  >to your friendly neighborhood dealer and asking him to look at it.
 
  I've fixed this problem on my mono monitor more than once. It is
  a power supply filter cap that goes south. Its a long way from the
  regulator chip (other side of the board), but it's easy to see that
  it's gone. Just open up the monitor and go looking for a blown cap.
  I mean really blown. It takes a 2.2 micro farad to replace it.

Then there is the flyback problem:

  My monochrome SM124 died (flyback) and my dealer told me that no
  monochrome monitors are available.


And from another newsletter:
  More Mono Monitor Failure Types
  -------------------------------
  The subject of failing mono monitors seems to come up regularly on
  USENET. Here's one failure mode:
 
    I've had recent problems with my mono monitor; there is a capacitor
    that has blown 3 times!  The first two times, it was replaced with a
    close but not exact one meeting the specs; this last time, my nearby
    atari dealer (in kansas city one hour away) got the correct one from
    california.  So far so good.  In any case, the symptoms where a black
    screen; if you open up the case, if it is blown capacitor you might see
    a mess since my literally exploded; there was also a smell.
 
    GOOD LUCK!!

  And here's information on another, from Neil Forsyth:

    Well I guess this as good a time as any to voice my sorrows too.  We
    have two SM124 monitors here with the same problem. We have carefully
    checked them against working ones and it looks like the line output
    transformers are dead. We have been waiting for months for a local
    Atari dealer to get us replacements but nothing has turned up yet. The
    dealer has quite a few SM124s waiting for repair and says he can't get
    the LOPTs for them. However he can get LOPT's for SM125's (The Tilt 'n
    Swivel monitor) but they are no use to SM124's.
 
    Unless we can get our hands on SM124 LOPT's we might have to buy new
    monitors and I don't want to get SM124's if I can't repair them.
    SM125's seem not to be on sale any more.
 
    BTW SM124's are made for Atari by Goldstar. Anyone know if they will
    supply the parts?

Finally, although I can't find a record of it, I seem to remember that a
common problem was the blowing of a varistor at the input power circuitry.
I believe someone said you could replace it with one from Radio Shack.

    
    HI,
    
    The symptoms I have are that of the LOPT arcing over or breaking down.
    
    It could just be I suppose an arc over from the HT lead to the chassis,
    if it is routed too close. I may make the effort to open up the case
    and check. (A good slober with silicon grease sometimes works wonders!
    
    Thanks for the info
    
    Pat
    

Thanks for the suggestions, Don and Pat, regarding cap, LOPT & varistor. 

In my case, whatever event the fuse was designed in to protect against seems 
to have occurred.  Does anyone know what sort of failure that might be?
My troubleshotting tactic, short of analysis, is to temporarily shunt the blown 
fuse with a 10 watt resistor to trickle some current into the circuit and see 
what gets hot. 

    
    
    Roy,,
    
    
    I am sorry, I replied to the wrong note!, fat fingers again. I was
    commenting on my mono monitor problem, which is the interrmittent
    collapse of the screen. Yours is the blown fuse, It could be anything
    in the mains I/p circuits, A better choice than a resistro might be a
    VARIAC transformer and wstart low and wind it up. 
    
    Sorry for the confusion.
    
    Pat K
    

    I bought myself a new SM124 monitor a month ago, mail order. After a
    few days of operation the screen went blank and the speaker buzzed
    steadily.
    
    Exasperated, I mailed it back to the mail order firm, which sent me
    another one after a wait for a shipment from Atari.
    
    It sat around for awhile, and then I used it for a few days and then
    the screenf went blank and the speaker buzzed.
    
    Really exasperated, I picked it up and dropped it on the floor from a
    height of four feet.
    
    It's worked fine ever since.
    
    Gil
    

Thanks Pat for the clarification and suggestion and thanks Gil 
for the story.  There seems to be a trend with Atari hardware 
that "dropping" is a sure cure for many ailments.  I think 4 
feet is a record height though.  People usually talk in terms 
of 2 inches. 

My intent with this note is to find out how common the video board 
fuse blowing problem is.  I guess it's pretty rare, since I haven't 
heard it mentioned by anyone else yet.