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View Full Version : Strange Voltage problems with MCP655-B pump



Navanod
02-02-2008, 09:33 PM
Hi all,

I'm having this strange problem with this new MCP655-B pump which replaced a leaky old Laing...

The pump was ran using a 12V DC external power supply during leak testing and bleeding. But when plugged into the 480W PSU after everything's alright, it refused to start and simply made small irregular vibrations without moving any water. RPM sensor detected small irregular rpm readings but no movement of water can be observed.

I checked everything and unplugged everything that i can from the PSU thinking the PSU may not have enough juice but that still failed to make it work. In desperation, I hooked it back onto the 12V DC external power supply and it worked! It gets stranger...after running the pump on the DC external power supply for awhile, I decided to give the PSU another shot. This time it worked! But when the system is shutdown'ed and restarted, the same problem resurfaced.

Hence, I had to "jump start" the pump each time for the entire day. I also noticed that although the pump's running, the rpm readers are still going all over the place

The next morning, because I had forgotten to switch the pump to the DC external power supply (its still on PSU), I turned the system on and to my surprise, the pump started! I monitored it for almost a week and there were no problems until yesterday, when the exact same problem returned...

True enough, the DC external power supply was able to jump start the pump once more and the PSU was able to take over. However, this cannot go on forever, esp when it's meant to be for my gal friend! She wouldn't be able to spot the problem if the pump didn't start, and everything will probably cook!

I've asked everyone I knew and no one seemed to know whats wrong and its driving me up the walls and so I had no choice but to turn to the forums. Although I had bought spare pumps, I really do not want to rebleed the loop if I could help it...

updates:

I suspected the PSU didn't have enough juice and had borrowed a variable power source from a friend to test...running it at 12V, the pump failed to work and was drawing only 0.02A for current, but at about 14V, the thing started up for a short while, drawing about 1.5A, then stopped again. Only at 16V did the thing started running...and doing this to jump start the pump and transferring it back to the PSU doesn't always work. Took a few attempts...which I suspect could be dued to the pump needing to warm up.
I've unplugged everything and left only the bare minimal required to boot the system (1 HD and the mobo). I've also tried it on all the 6 molexes on the PSU (Acepower 480W). No go.
I know the pump was rated to run at 12-24V, but now it seemed to require 16V to start...very odd indeed.

Hope this wall of text is not too much for you guys to digest :eek:

STEvil
02-02-2008, 09:53 PM
bad connection to the 480w psu maybe, check the pins in the molex connector for the pump.

Martinm210
02-02-2008, 10:07 PM
Strange. You could just run it at 24V, it doesn't draw that much more power because the circuitry built in turns it down to about 13.1V from some testing I did.

But I'd be worried that the pump in on the way to failure. Probably not worth the risk, I'd at least plug the RPM cable in and use speedfan or something to shut down if the pump fails.

Navanod
02-02-2008, 10:18 PM
bad connection to the 480w psu maybe, check the pins in the molex connector for the pump.

Tried all the connectors...its not bad connection

Navanod
02-02-2008, 10:18 PM
Strange. You could just run it at 24V, it doesn't draw that much more power because the circuitry built in turns it down to about 13.1V from some testing I did.

But I'd be worried that the pump in on the way to failure. Probably not worth the risk, I'd at least plug the RPM cable in and use speedfan or something to shut down if the pump fails.

Yes...I'm not so much worried about the power drain than the reliability of that pump...looks like I should write in to request for an RMA....

STEvil
02-03-2008, 12:23 AM
Tried all the connectors...its not bad connection

You stated that, but you did not state whether you looked at the connectors on the molex of the pump. Check them as well.

Navanod
02-03-2008, 12:31 AM
You stated that, but you did not state whether you looked at the connectors on the molex of the pump. Check them as well.

Thanks for the reminder...checked that many times but nope...the bug's not there :shrug:

septim
02-08-2008, 04:21 AM
picture of the setup...

csjsi
02-09-2008, 03:45 PM
Well, knowing that the D5 can run off 24V, and seeing the issues Navanod had come across, made me think that maybe my pump just wasn't getting the juice it needed.

So did a bit of research on the net about getting 24V out of a standard PSU and came across this page: http://www.afrotechmods.com/fanmod.htm detailing how you can get more voltage for your fans from the same power supply.

Well we had an old ATX and an old AT PSU lying around in an unknown state, so we decided to give this a try. To cut a long story short, the ATX PSU didn't get very far, we were pretty sure it was dead and it seemed we were right. However, we figured you could probably do the same thing with an AT psu.

All you have to do to get 24V out, is connect +12V (usually yellow) to the positive side of your pump power connector, and -12V (brown in the ATX connector we had, and blue in the AT PSU we had) to your negative side.

You can find the pinouts for the AT psu here: http://pinouts.ru/Power/MotherboardPower_pinout.shtml

We tested the blue and yellow from the AT psu with a multimeter and we got a steady 23.2V so exactly what we wanted. Then, chopped off one of the other connectors that we didn't need any more, and wired the yellow and the blue into that so that we could plug our pumps straight in.

Here's the finished result:

With my system when I had my pump plugged into this, the pump carried on A-OK as if everything was golden, when I plugged my pump back in to normal 12V from my PSU, the issues returned just as before - pump runs for a few seconds, then cuts out, only to begin all over again.

So far as I can see this is probably the cheapest and easiest way to get a dedicated 24V connection for your pump. The only downside is that you then have to remember to turn that PSU you on before your pc etc.
__________________

Navanod
02-09-2008, 08:37 PM
Well, knowing that the D5 can run off 24V, and seeing the issues Navanod had come across, made me think that maybe my pump just wasn't getting the juice it needed.

So did a bit of research on the net about getting 24V out of a standard PSU and came across this page: http://www.afrotechmods.com/fanmod.htm detailing how you can get more voltage for your fans from the same power supply.

Well we had an old ATX and an old AT PSU lying around in an unknown state, so we decided to give this a try. To cut a long story short, the ATX PSU didn't get very far, we were pretty sure it was dead and it seemed we were right. However, we figured you could probably do the same thing with an AT psu.

All you have to do to get 24V out, is connect +12V (usually yellow) to the positive side of your pump power connector, and -12V (brown in the ATX connector we had, and blue in the AT PSU we had) to your negative side.

You can find the pinouts for the AT psu here: http://pinouts.ru/Power/MotherboardPower_pinout.shtml

We tested the blue and yellow from the AT psu with a multimeter and we got a steady 23.2V so exactly what we wanted. Then, chopped off one of the other connectors that we didn't need any more, and wired the yellow and the blue into that so that we could plug our pumps straight in.

Here's the finished result:

With my system when I had my pump plugged into this, the pump carried on A-OK as if everything was golden, when I plugged my pump back in to normal 12V from my PSU, the issues returned just as before - pump runs for a few seconds, then cuts out, only to begin all over again.

So far as I can see this is probably the cheapest and easiest way to get a dedicated 24V connection for your pump. The only downside is that you then have to remember to turn that PSU you on before your pc etc.
__________________

beware my friend, my pump runs very hot when on 16V...this may burn it out faster as well as dump so much heat into the water that it becomes a heat source!

Navanod
02-09-2008, 08:39 PM
picture of the setup...

Apologies...here it is

http://i196.photobucket.com/albums/aa3/Navanod66/Lian02.jpg

Navanod
02-09-2008, 08:40 PM
My new pump is running great now...
the old faulty one had been sent back for RMA...maybe Swiftech can tell me wat was wrong...i'll post again if i hear from them

thanks for all the great help

crazysurfanz
02-09-2008, 11:27 PM
So you just RMA'd it and got a new one then? The new one runs fine at 12V?

STEvil
02-10-2008, 12:34 AM
maybe a batch with bad mosfets came out or something.

Navanod
02-10-2008, 07:35 PM
So you just RMA'd it and got a new one then? The new one runs fine at 12V?

Yes, new one ran wonderfully :clap: