Re: EASY solution for sudden RESET problem on WPC games
- From: beaver <ed@xxxxxxxxxxxx>
- Date: Mon, 11 Feb 2008 03:35:21 -0800 (PST)
This repair seems to me to be a bandaid also. If I saw this on a
machine I bought, I would remove it and find what is wrong. There are
many machines out there (mine included) that work day in and day out
without it. Needing one just means something needs to be repaired.
Edward Cheung CARGPB26
On Feb 11, 12:30 am, "Mark Clayton" <spamuser1...@xxxxxxx> wrote:
Leon:
I would agree that your explanation shows that the diode is not needed,
but adding the capacitor as you describe is just masking the true
problem. The LM323 is unable to properly regulate when the regulator
input voltage dips below the about 7 Volts (the output voltage plus the
drop-out voltage of the regulator). On Williams WPC's, this should
be at least 10 Volts, so if it dips below 7, there is a serious problem
elswhere. The big cap on the output may do a good job of sustaining
the 5 VDC output of the regulator when it drops out due to inadequate
input voltage, but the original problem sitll remains. And if the problem
is weak or failing diodes or filter capacitors, the problem will get worse over
time until even the "fix" may stop working.
It's a "perfect" fix for an operator with a game on location wanting to get
the game functioning quickly and cheaply, but I wouldn't recommend it
as a real and permanent fix .
As for the size of the capacitor being a problem, it's not. The regulator
can handle short circuit conditions, so charging a big cap will always be
current-limited to a reasonable value. So if you really want to do this mod,
putting in a big capacitor certainly won't hurt anything.
-Mark
--http://pinballpal.com
"news" <leon...@xxxxxxxxxx> wrote in messagenews:47aea7b9$0$837$5f6aeac3@xxxxxxxxxxxxxxxxxx
Sorry for the delay of my answer, but when you guy's are awake in general we
in Europe are sleeping !! LOL!!
About the capacitor on the output of the LM323 indeed it is mentioned in the
datasheets to avoid discharging backwards trought the LM323 BUT this occurs
mainly when the load is disconnected BEFORE cutting the 5 volt supply ,
like when using a regulated supply on the bench you connect devices to test
/ to repair / and so on to your regulated supply and when all is done and
everything is disconnected you switch of the regulated supply.
In our case when the pinball machine is switched off, the load ( all of the
IC's on all of the boards) remains connected on the 5 volt supply , the
capacitor will completely discharge trought the load and not trought the
LM323. Remind that the resitance of the load is several times lower then the
resistance of the inverted LM323.
About the value of the capacitor, there you can try a lower value ,
depending on the " wear" of BR2 and C5, perhaps i should change that on the
site, and recommend to start with 2200µF and going up until the reset is
gone.., but for a universal case i just put 15.000µF.
Not difficult to do , when the two wires are soldered on the CPU board it's
easy to change the capacitor
leon
"David Schulpius" <dschulp...@xxxxxxxxx> schreef in bericht
news:a95b35a1-1c81-4874-bf2c-3698467f5176@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Feb 9, 6:31 pm, c...@xxxxxxxxxxx wrote:
On Feb 9, 12:06 pm, "news" <leon...@xxxxxxxxxx> wrote:
Hello,
rectifierI found a simple solution to this problem, no need to change the
undoor the capacitor C5 , no need to take out the power driver board and
all connectors!
Find the new article on my site under link button 6
Http://www.flipper-pinball-fan.be
leon
Leon,
this is not a good solution at all.
First, I have to say, that the guys at williams
actually knew what they were doing! They
didn't put a 15,000 mfd cap where you propose
for a reason (besides cost), as Ed has identified
in another post.
C4 is a 100 mfd cap. Bumping this up a bit
to 470 or maybe 1000 mfd would be Ok. But
going to 15,000? That's just crazy talk.
and it will damage the power supply eventually.
This debate is fascinating. I love to watch people that really know
what they are talking about discuss their ideas in a civil manor. I
really respect most of the people who have posted in this thread so
this should be interesting.
I was real excited about an easy fix to this reset problem but it
seems that possible harm could occur from it without precautions. I'm
no electronics expert so I cant wait to hear why Leon went with such a
large Cap and if he thinks it will harm the power supply. Sounds like
he did a lot of testing and I wonder if a smaller cap like Clay
suggests would accomplish the same thing?
I know there was a lot of debate about another fix concerning this
reset problem. That idea was to change the tap on the transformer to
rise the voltage a touch. People said that that would put undo stress
on the board system. Others said it was no big deal as they were built
to take the higher voltage. There was never a clear cut conclusion to
that debate that I could find. We may have the same outcome here.
Cant wait, Dave
.
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- EASY solution for sudden RESET problem on WPC games
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- Re: EASY solution for sudden RESET problem on WPC games
- From: David Schulpius
- Re: EASY solution for sudden RESET problem on WPC games
- From: news
- Re: EASY solution for sudden RESET problem on WPC games
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