tec killed?

[yaboc]

my TEC was working and suddenly it stopped. i didn't even thouch it. Called swiftech about it and they said that uneven pressure on the cold plate can kill the tec as well as i need the right tools to assemble tec. they didn't give me RMA and now I have to buy another tec. i asked if i could send em the block and they can do it for me as they have the tools. this whole tec adventure is becoming really costly for me.

yabOC

[wfarid]

man that sucks a$$, wait werent u the one that dropped ur entire system 2?

[yaboc]

yes, this is going to be third tec!!!
i don't know how the TEC got killed. I turned on the system and the temp was 6C after few minutes it jumped to 45C. i took out the tec and tested it by itself and couldn't get it to work. there's no visible physical damage of any kind (melted stuff, burns etc). Meanwell was giving steady 12v. I just can't think of a reason why it failed. Any ideas?

[wfarid]

wow... thats all i can say, i feel bad for you...

[Synthohol]

ok, it gave 12v but were the amps ok? I'm not trying to be funny

[yaboc]

my DMM can only go up to 10A so i cant take the reading or maybe im doing something wrong. it was like $15

[dino-new]

The amps should be fines as it will only draw what it needs. If you're using a meanwell and the voltages are good then you can rule that out. I would watch the voltage on powerup to see if it's spiking higher than 12v. It's probably not but it's worth a shot.

I'm sad for you, but you probably will find the problem, just take your time and logically eliminate what it's not. How much pressure are you using to tighten the tec unit in? What swiftech block are you running? After taking the tec out can you notice any cracks around the potting? Also did you check to see if the meanwell relay is shutting off for some reason? There should be a light on the meanwell that indicates it's getting power. how's your flow rate?

If it's not the power supply then I would take a real close look at the flow rate travelling through the waterblock. If the flow stops it will do exactly what your describing. So is your pump still pumping or is it shutting off for some reason?

I hope this helps,

Devin

[Player0]

The only decent way to test a peltier is to measure it's amps and voltage. A peltier is a mix of series and parallel elements, which means a damaged peltier is going to draw a different amperage OR voltage.

You need to measure both by taking these measurements in SERIES with the peltier. So negative from the PSU to the negative on your meter, and the ppositive from the meter to the negative on the peltier. Measure the voltage here. It should read 0v, which means that the peltier is using a full 12v. If the meter reads anything over 0v, then something is goofy.

NOTE: Can someone confirm this? My electronics may be rusty and I dont want someone throwing a peltier away on this basis.

Amperage I am sure will be the best testing tool. If your meter only goes up to 10a, then you can still test this. The first option is to connect a large wire-wrap resistor with a very low resistance in parallel with your ohm-meter while testing, and then using math to determine the actual amperage. This is a nightmare.

Another alternative would be to connect the peltier to the 3.3v or 5v line. The peltier will respond almost directly proportionate to the lower voltage. So if it draws 19a at 12v, and 25a at 16v, then at 5v it should draw 7.8a. Now, its not a DIRECT ratio, and could be an amp or two off. But if its not drawing at least 6 amps at 5v, then you know the peltier has been damaged.

Just dont do this testing with the peltier on the CPU.

[dino-new]

There's actually a much easier way and safer on the meter and power supply. just measure the resistance in the pelt and see if it matches the manufacturer ratings. if not then there's definately a prob. If it does match the manufacturer's ratings then it may be OK. I guess it's up to you if you want to test it further.

[Player0]

You cant measure the resistance of a peltier because it will act like a capacitor, and the resistance will change depending on temperature.

[dino-new]

I wonder why some manufacturers list the ohm (resistance) rating of their tec modules? Perhaps you know?

[Player0]

Its the resistance under a given set of circumstances. Ask for the performance charts from the manufacturer. You can usually get graphs and extended data for the modules. I have this data on many of the common modules.

[mdzcpa]

Man, what a bummer yaboc:( Pelt cooling shouldn't be this hard. you've had a string of bad luck.

Did you double check that the Meanwell was still working okay?

Usually when a pelt goes bad from uneven pressure, you can see a crack in the ceramic. But not always.

Does the pelt get cold at all?

[Gregorach]

Originally posted by Player0
The only decent way to test a peltier is to measure it's amps and voltage. A peltier is a mix of series and parallel elements, which means a damaged peltier is going to draw a different amperage OR voltage.

You need to measure both by taking these measurements in SERIES with the peltier. So negative from the PSU to the negative on your meter, and the ppositive from the meter to the negative on the peltier. Measure the voltage here. It should read 0v, which means that the peltier is using a full 12v. If the meter reads anything over 0v, then something is goofy.

NOTE: Can someone confirm this? My electronics may be rusty and I dont want someone throwing a peltier away on this basis.
[...]

I always thought you'd normally measure current (amperage) in series and voltage in parallel. When measuring voltage, your meter should have an effectively infinite internal resistance, if I remember my electronics correctly. Contrawise, it should have zero resistance when measuring current. Otherwise, you end up measuring the properties of your meter rather than the thing you're actually interested in...

[Player0]

Thats all true Gregorach.

I thought maybe you could measure 'left over' voltage with a meter in series. But im not sure how it's impact would react with the circuit. Id have to test it at home, Im pretty rusty like I said.

Its best just to measure the current of the beastie.

[Gregorach]

Yeah, I'm not too sure... If you put the meter in series, then it's acting as a potential divider - that's why the impedance needs to be ~0 for measuring current. In a potential divider, the potential difference is divided in proportion to the two impedances. I think that if you switch the meter to voltage mode, it's impedance becomes very large as compared to the TEC, so almost all of the voltage drop will be across the meter - the actual voltage across the TEC will be pratically zero, and would be so regardless of the impedance of the TEC (assuming it's not blown completely).

[Player0]

Yeah, I think your right Grego. :)

[dino-new]

yaboc,

have you found the reason for the failure yet? I think we're probably all curious how you're doing with this.

[dino-new]

Gregorach,

Can you put a 10 amp meter in series with over 10 amps and measure the amperage? Or will it overload the meter and blow a fuse?

[Player0]

It will blow the fuse. Thats pretty much the point :)

Get a larger meter (mine does up to 25a) or, just use a lower voltage line and measure the current on a scaled down test.

[dino-new]

I would verify that the liquid flow is flowing across the hot plate and that you're getting the proper voltage to the tec module. Then disconnect the pelt and test the ohm rating at room temperature, compare it to the specs from the manufacturer.