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Fried my Q137 fuse
MUFF WIGGLER Forum Index -> 5U Format Modules  
Author Fried my Q137 fuse
Kai
I received my synthesizer.com modular today. I connected everything and then immediately fried my Q137 fuse. What could have happened?

Situation
I've got a normal PSU & cable harness.
I connected just 6 modules to the PSU via the harness.
I switched the Q137 to 230V (Holland).
I didn't connect the cable harness output to the PSU, (which is only for the indicator lights and connecting another modular to it).

Tomorrow I'm going to buy a new fuse, but before I connect this I would like to know what could have gone wrong?

Thanks!
kindredlost
I am assuming you've written to Roger Arrick about this?

This kind of thing is an everyday part of troubleshooting. More than likely there is a power cable connector that is plugged in wrong to a module. Easy to do. I'd certainly give it a thorough triple check.

The contact page at synthesizers.com is where to send Roger a mail. He is pretty quick about a response.

Good luck.

-David
bwhittington
Your problem could be as simple as an underrated fuse, or your could have a short circuit somewhere in your synth. I would start by inspecting all the wiring for an irregularities (bare copper that could touch something else, etc). Is it possible that any of the stray DC power cables in the harness could have touched one of the boards? Even though they are in protective plastic housings, it isn't inconceivable that they could make contact with other conductive parts. Did you smell anything burning, and so on.

That's just me taking an untrained stab at your problem. I'd definitely wait until you hear back from Roger before powering up again. But the more information you have, the more likely you will be to solve the puzzle.

Cheers,
Brian
100th Monkey
I had the same problem with my Q137 a few years ago. It turns out they'd wired the voltage selector backwards so 115V was actually 230, and 230 was actually 115. I went through about half a dozen fuses until I figured it out. Roger sent me a replacement module as soon as I told him what the problem was.
Kai
Thanks for the fast replies guys! Yeah I mailed Margo back with the questions. The fuse which was in the machine was 3A/250V. Pretty heavy for such a machine isn't it? The cable which provides the 230V to the PSU goes totally free, doesn't touch anything. All cables are triple checked and were tie-wrapped from the beginning. I don't smell anything strange, so I guess nothing really heavy has burned?

Would it be an option to only attach the Q137 to the PSU, switch the AC voltage to 115 and see if the fuse fries again? And if it doesn't, to attach module per module to the PSU and check everything, every time?

Ha, I know I better wait for Roger. wink But it's all pretty strait forward and I can't see anything else which could have been connected wrong..?
100th Monkey
Kai wrote:
Would it be an option to only attach the Q137 to the PSU, switch the AC voltage to 115 and see if the fuse fries again? And if it doesn't, to attach module per module to the PSU and check everything, every time?
That's what I did.

I'd recommend first trying it on 230 with a new fuse and nothing else connected to see if it blows right away. If it does, pop in another fuse, set it to 115 with nothing else connected and see if it blows again. If it doesn't, attach an envelope or something with an LED for use as a quick visual check and try it again at 115. If that works, add another handful of modules and see what happens. If everything still seems ok and you're feeling brave, set it back to 230 and see if it pops the fuse again.
Just me
A voltmeter might be a handy check device instead of an expensive module.
giorgio
yes. check the PSU alone & with meter. meter is cheap if you don't have one. cheaper than blown modules for sure no matter how you look @ it

peace/luck 2 u
Kai
Mmm, I removed the harness, tried another fuse and it fried. Changed it to 115V and it fried. So when only the PSU is connected, there is still something wrong. Only without the PSU connected the fuse doesn't fry. screaming goo yo
kindredlost
Just me wrote:
A voltmeter might be a handy check device instead of an expensive module.


Such clear-headed logic - it's stunning! hihi

BTW Kai, is the power supply from Roger or is it a different vendor item? I suppose you should check the output of it too. That is something Roger will ask you about anyway so you might as well test it.

-David
bwhittington
Well, he can't check the psu output if the fuse is blowing when he turns it on! Mr. Green

The most likely causes of a blown fuse are an overloaded electrical circuit (house) or a short circuit or ground fault in the PSU.

I assume you are using a power outlet in your home that is functioning normally and works fine with other appliances, etc? I guess the place to test with a voltmeter might be the outlet you are plugging into. If there is nothing irregular about that, then I would guess that the power supply is either faulty or was wired incorrectly (again, just me guessing). Often that information is written on the power supply itself, or you can look up the part number online to find a datasheet.

Roger will probably frown on you turning that into a DIY fix for liability reasons, but you can check for troubleshooting purposes and decide for yourself to fix it or not if you spot anything out of order. If you want to post the power supply info and a couple of photos, I'm sure someone here could help.

Just in case in needs to be said, I would strongly recommend against trying a bigger fuse. 3A is waaay more than adequate for your load already. No need to burn your house down!

Cheers,
Brian
doctorvague
bwhittington wrote:
Well, he can't check the psu output if the fuse is blowing when he turns it on! Mr. Green


I think the idea was to check the PSU for voltage independent of the modules.
Whatever the PSU is putting out is getting distributed to all modules the same unless there is one of the power supply fanout wires that happened to be wired wrong or something. Very unlikely but I had a similar thing with another vendor so it's not impossible.

I would suggest measuring the voltage at the power supply with the 137 not connected. I would also check the specific power cable from the wiring harness that you're plugging into 137 - visually expect to make sure it wasn't wired backwards or one wire out of place or something i.e. make sure it is wired exactly like a known working one. Other than that my money is on a defective module or a solder bridge on it or something. I'd also ask Roger about the fuse value and type to make sure it is correct. Maybe a wrong fuse was put in at the factory. Just some ideas.
bwhittington
I'm still not understanding that. The IEC connector is on the Q137, which in turn is connected to the psu. I guess you are suggesting he wire his his own inlet directly to the psu? If that worked, he should probably just return the Q137 for a refund, since he would have essentially DIY'ed its function. But short of that, I don't understand how he would measure the psu's output voltage if the fuse is blowing as soon as he turns it on . . .

hmmm.....

Cheers,
Brian
doctorvague
bwhittington wrote:
I'm still not understanding that. The IEC connector is on the Q137, which in turn is connected to the psu. I guess you are suggesting he wire his his own inlet directly to the psu? If that worked, he should probably just return the Q137 for a refund, since he would have essentially DIY'ed its function. But short of that, I don't understand how he would measure the psu's output voltage if the fuse is blowing as soon as he turns it on . . .

hmmm.....

Cheers,
Brian


OOPS. Apologies!
I didn't realize the 137 was the power module I was thinking it was another module. Other than a few, I get the numbers mixed up pretty often TBH.

EDIT: hey we keep each other honest around here and that's a good thing!
doctorvague
doctorvague wrote:
bwhittington wrote:
Well, he can't check the psu output if the fuse is blowing when he turns it on! Mr. Green


EDIT: PLEASE DISREGARD THIS:
I think the idea was to check the PSU for voltage independent of the modules.
Whatever the PSU is putting out is getting distributed to all modules the same unless there is one of the power supply fanout wires that happened to be wired wrong or something. Very unlikely but I had a similar thing with another vendor so it's not impossible.

I would suggest measuring the voltage at the power supply with the 137 not connected. I would also check the specific power cable from the wiring harness that you're plugging into 137 - visually expect to make sure it wasn't wired backwards or one wire out of place or something i.e. make sure it is wired exactly like a known working one. Other than that my money is on a defective module or a solder bridge on it or something. I'd also ask Roger about the fuse value and type to make sure it is correct. Maybe a wrong fuse was put in at the factory. Just some ideas.
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