Got a Dell computer with something called a 110 Twin Alert. This little board on the top of the chassis is shutting down the power supply. I thought it might have been some kind of temperature alert gone bad. Got Got some power circuitry with a beeper. ??
greg
On Tue, 28 Apr 2009 18:21:38 GMT, snipped-for-privacy@zekfrivolous.com (GregS) put finger to keyboard and composed:
Could it be this warning device with a 110dBa sounder and a low wattage speaker?
The pinouts are:
Symbol Description
---------------------------- - 0V + 12V BA Siren Trigger SPK Speaker T Tamper T Tamper
I can't see how it would be responsible for shutting down your power supply, though.
- Franc Zabkar
Thats was interesting. I will post a picture later.
greg
So here is a picture. I think its just a temp warning beeper that went bad and shorting out supply. Weird.
greg
On Wed, 29 Apr 2009 15:50:59 GMT, snipped-for-privacy@zekfrivolous.com (GregS) put finger to keyboard and composed:
shorting out
It looks like the Pyronix device is something completely different. How do both trademarks coexist ???
Here is a PC Power & Cooling alarm that is similar to yours.
110 Alert Heat Alarm:It is set to go off when the temperature reaches 110 deg F. It doesn't appear to do anything other than alert the user, though.
OTOH your device appears to shut down the PSU. You can see the thermistor below the second M in the LM339M quad comparator. Could that be a crowbar SCR across the +12V or +5V input? What are the two large parts at the RHS of the PCB?
The only useful reference I can find to TwinAlert with Google is this one:
This is a Google translation: ================================================================ Sensory devices for heat
Thus, this problem could be avoided entirely by using the company's
110 Twinalert PC Power and Cooling Systems. Twinalert represents 110 bus to the size of a credit card that is connected to the plug such as power flopito. When the temperature in the PC-it reaches 43 degrees, the device starts to squeak, creating annoying noise, and in 47 degrees just excludes computer. It cost under $ 50 ... ================================================================- Franc Zabkar
shorting out
LM339 is a quad comparator. The board is also legended 'power and cooling'. I'd guess it monitors temp and several supplies.
Graham
shorting out
It looks like it's monitoring the temperature (there's a thermistor on the bottom right of the PCB). I notice that it has a local regulator, which I'd be guessing is a 7805 that's shorted out.
On Thu, 30 Apr 2009 19:44:02 +1000, Bob Larter put finger to keyboard and composed:
The pinout for a 7805, from top to bottom, is "In Gnd Out". This doesn't fit with the "+12V Gnd Gnd +5V" pinout of a drive connector. In any case why would you need a local +5V regulator when the incoming supply already provides +5V? If for some reason you did need a +5V regulator, then wouldn't a 78L05 be adequate for this circuit?
- Franc Zabkar
That heatinked device seems rather odd, not least the way it's mounted with bent leads.
Graham
Yeah, you're right about it not being a 78xx reg. I must've been a bit slydexic when I first looked at it.
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