TECH: My first failure on 4th run LOTR

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The display. 4th run LOTR. Feb 05 date code.

While playing a game, (and during the third ball), I looked up and no
display!

So pulling the back glass I noticed a little smoke streamer rising from
the display power supply, (upper left corner).

Naturally I kill the power immeadiately. Q3 and it's heat sink are
pretty hot. Amazingly, upon bench testing I find no failed components,
not even the fuse is bad. So I replace Q3, MJE15030 and Q2, MPS A92.
Power up the supply without the display connected and open voltages are
good. -109 on the -120 and -96 on the -100. Good enough.

Power down and reconnect the display briefly. Dead. LED on controller
is on. Power back down and remove the display from the framework,
(what a bitch!). I temporarily strap in another display and everything
is OK.

I mount the spare display onto the framework, put the weatherstripping
around the glass, and put it back on the game. I somehow have done
something a little wrong in the assembly as some light is seeping onto
the glass from the backbox lamp. (Fix that later but thought I would
mention it).

I am at a loss to explain the high current draw that apparently took
place across Q3 without taking out the fuse. It has the proper fuse
value, (from factory).

So here is a heads up post for your notebooks! The fuse may not
protect the components and there will be heat!

Mario
Pinthetic
 

Del

Distinguished
Oct 3, 2001
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Mario,
We've been replacing these & Displays just about every 6 months
on the Sterns we have here,,, Never seen games burn a Display up like a
new Stern,

Games running 12 hour days & "I" still think its a design flaw.

Pin-Del,
 
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Del,

Thanks for the info. This one is a HUO, just my daughter and me, and
that is what surprises me. I'll bet this thing has less than 100 hours
on it. I have a T3 in a calm location, for about a year now, where it
is only on during certain hours, and it has not given me a problem as
far as the display. It did have the screaching problem and Stern took
care of that for me.

Mario
Pinthetic.
 
G

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> I am at a loss to explain the high current draw that apparently took
> place across Q3 without taking out the fuse. It has the proper fuse
> value, (from factory).
>
> So here is a heads up post for your notebooks! The fuse may not
> protect the components and there will be heat!
>
> Mario
> Pinthetic
I remember a joke (not funny to techs). The 10 dollar transistor will blow
every time to protect the 10 cent fuse.. I'm talking early SS Pins, and
pre switching power supply videos.
 
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Update:

Vishay-Dale is going to do a factory direct warranty replacement on
this unit. For those who don't know these are shipped to Stern with a
one year warranty.

Mario
Pinthetic
 
G

Guest

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Good to hear they're standing behind it. Do they think the dispaly
caused the power supply to go, or vice versa (or do they not know
either way). It would be interesting to know how to prevent this, as
it seems to be a trend (from what I've read). It would stink to lose a
perfectly good $100 display out of warranty due to a correctable design
defect in the power supply. As the Vishay-Dale displays are used in
WMS games without incidence (that I've heard), I doubt the defect is in
the display design, but it could have been a bad unit drawing too much
power.

h_h
 
G

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Del mentioned earlier that he is going through these at about one every
six months and he believes there is a design flaw. I tend to agree
with him based on what I experienced. The +60 volt section was pulling
enough current to get Q3 hot enough to smoke and not take out the fuse.
That my friends, is a design flaw. Maybe a fuse or thermal resistor
missing from the design? I can't see allowing the +60 volt power
section to be destroyed on this little board without some resolution.

Lynne, at Vishay, gave me a little vocal tutorial on what they believe
happens to these. She says they were designed to be left on for
extended periods of time, and if not used that way they tend to fail.
She also mentioned that it is harder on the unit to be "blank"? Sounds
like the voltage is high when the display is blank, and that stresses
the components due to tight tolerances. This may help answer Grim's
question about, how long do they last in a home enviornment?

I downloaded the pdf brochures for this display to do a little
background study. There are two versions of this unit. One version is
the "A" version, and that apparantly is not the one we are using.

On a side note, if the Stern tech crew hasn't picked up on this post
yet, I will probably call and talk to Joe or Chas next week about this
issue just to get their take on it. If anyone has any other
experiences, or info, on this topic please chime in! Misery loves
company!

Mario
Pinthetic
 
G

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Pinthetic@gmail.com wrote:

>
> Lynne, at Vishay, gave me a little vocal tutorial on what they believe
> happens to these. She says they were designed to be left on for
> extended periods of time, and if not used that way they tend to fail.

So does this mean that turning a game on and off every day (or several
times a day) stresses it? Does it mean the game should be left on for
a certain period of time? OPs turn off their games once a day, so I
don't see how HUO could be more stressful unless the display needs to
be on for a certain period (which makes little sense). I could see how
power cycling could be stressful.

> She also mentioned that it is harder on the unit to be "blank"? Sounds
> like the voltage is high when the display is blank, and that stresses
> the components due to tight tolerances.

Unless WMS games tend to blank less (more graphics?), this shouldn't be
any different on a Stern.

> This may help answer Grim's
> question about, how long do they last in a home enviornment?
>
> I downloaded the pdf brochures for this display to do a little
> background study. There are two versions of this unit. One version is
> the "A" version, and that apparantly is not the one we are using.

Was the A version a higher quality standard?

>
> On a side note, if the Stern tech crew hasn't picked up on this post
> yet, I will probably call and talk to Joe or Chas next week about this
> issue just to get their take on it. If anyone has any other
> experiences, or info, on this topic please chime in! Misery loves
> company!

Please post back to the group anything you learn from Stern. Thanks!

h_h