Re: LM323-K adventure and lesson
- From: "martin" <martin.reynolds@xxxxxxxxx>
- Date: 7 Mar 2007 11:52:48 -0800
On Mar 7, 10:50 am, i...@xxxxxxxx wrote:
My apologies, I misunderstood. Putting a diode or zener diode on the
reference pin to ground makes sense
On Mar 7, 12:45 pm, "RonKZ650" <RonKZ...@xxxxxxx> wrote:
You're not understanding the entire thread. We are talking about
putting a diode or resistor from the reference pin of a regulator IC
to ground in effect raising the volt output a certain amount. In no
way is anyone suggesting putting a diode or resistor in series with
anything.
On Mar 7, 9:44?am, i...@xxxxxxxx wrote:
Dont listen to these opinions...puting resistor in series or using a
diode is insane. ?If you draw even an amp of current with a 30 ohm
resistor, you would be pulling 30 Watts of power, no 1/2 watt resistor
could ever survive. ?A diode would fail quickly under this type of
power requirement as well. ?Since you are getting 4.91Vdc you have no
worries. ?Specs matter always check into them before you replace any
major components.
On Mar 6, 10:53 pm, "hagis_u" <ss1941...@xxxxxxxxx> wrote:
Very well said...I would agree with both of your points
On Mar 6, 9:17 pm, "GPE" <See_GPE_webs...@xxxxxxx> wrote:
"hagis_u" <ss1941...@xxxxxxxxx> wrote in message
news:1173209500.920532.93670@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
While playing some TZ on the weekend the pin went completly dead. ?I
removed the backglass and noticed the CPU board LED's were all off. ?I
metered the 5 Vdc test point on the power driver board...0 Vdc. ?I
then decided to check the output on positive terminal BR2...6
Vdc...time to replace it. ?So I thought might as well replace BR1 and
the LM323-K, 5 volt DC regulator and update these 14 year old parts.
After replacing BR1, BR2, and the LM323-K, my TZ reset when I pressed
the flippers (I replaced all the 15000 uF caps last year). ?My first
thought was "What the hell is going on now". ?I put my meter on the 5
Vdc test point and got 4.73 Vdc, and I noticed the CPU board would
reset whenever the voltage dropped below 4.72 Vdc. ?I proceeded to
check all the parts I had replaced, the connections, reseated all the
connectors and no luck the same result. ?A friend of mine who works in
the electronic components industry asked me what parts I used...he
said all looks good...who is the manufacturer of your LM323-K ? ?I
looked at the name on it "ST micro". ?He looked up the data sheet and
the spec indicated an output of 5 Vdc plus or minus 0.3 Vdc.
Depending on ?your luck the ST part will produce an output between 4.7
and 5.3 Vdc, at 4.73 Vdc I was within their spec. ?He gave me a Linear
Technologies (LT) LM323-K , whose spec is 5 Vdc plus or minus 0.1
Vdc. ?Put the new piece in and the output is at 4.91 Vdc, all is
well.
Lesson learned all LM323-K's are not created equal...a frustrating
lesson. ? It was all worth it in the end, the TZ is working properly.
This has been discussed multiple times on this newsgroup -- do a search for
LM323AK's.
The name "ST Micro" has nothing to do with the output voltage. ?The
difference isLM323Kversus LM323AK. ?The AK's are a closer tolerance parts
than the K's. ?That tolerance may be on the high side or on the low side.
If on the low side (as you had) - then problems arrise. ?The AK parts keep
you in closer to the +5V and out of the reset generator's range.
This is all due to poor design on Williams part.
1 -- they used as low as possible voltage on the input. ?Any fluctuation in
supply voltage (i.e. AC, cap or bridge) causes the LM323 to go out of
regulation and the output sags.
2 -- they used too high of a threshold for their reset generator. ?A
slightly lower threshold on the reset generator eleminates a lot of resets.- Hide quoted text -
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The bottom line of all of this is that dropping in the LT part is a
really good solution. It is a close-tolerance 5A part that just isn't
going to struggle so much. Failing that, the LM323AK part is a good
second choice.
Part of the problem is that the part is running at a pretty high power
level - it has over 12V coming in, which means that it has to waste
20W or so - I've never checked, but I suspect that these systems take
a fair amount of current. And Williams has no slack in the design - if
the connectors or wiring have a shade of resistance, there could be a
lot of resets. There again, the reset problems aren't that common
given the number of machines out there
.
- References:
- LM323-K adventure and lesson
- From: hagis_u
- Re: LM323-K adventure and lesson
- From: GPE
- Re: LM323-K adventure and lesson
- From: hagis_u
- Re: LM323-K adventure and lesson
- From: idol
- Re: LM323-K adventure and lesson
- From: RonKZ650
- Re: LM323-K adventure and lesson
- From: idol
- LM323-K adventure and lesson
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