loose, red hot resistor - DK600 problems

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Alex E
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loose, red hot resistor - DK600 problems

Post by Alex E » Thu Jun 09, 2011 8:18 pm

Well, my first foray into pure analog synthesis in years did hit some potholes. But thankfully this has a warranty.
Here's the issue:

I get the synth via Fedex. I unpack the synth, it's well packed. 5 layers of bubblewrap and its floating in a sea of packing peanuts. What a mess, but it works. But there's a part rattling around inside.

I open the synth, which was serviced inside and out this year by the people I bought it from, and find a big, white, ceramic 12ohm 10 watt resistor that had gotten knocked loose from the power supply. No idea what happened. The synth obviously isn't working at all without it, so I find where it used to be and put it back, but it needs to be soldered in again.

But strangely enough, with the legs resting in the holes, it works. Kind of.
It'll run fine for about 15 minutes, but then it'll suddenly jump back to patch '00', or hang onto notes, or just freeze up completely, and I'm pretty sure it's the resistor, which at that point is getting so hot it will literally burn my fingers!
I don't think it's supposed to get THAT hot, Not to mention there were apparently little ceramic things covering the legs that are now missing. I do want to keep playing, but I don't want to hurt the machine.

I can do the following:

Try and get the sellers permission to replace the resistor myself (so I don't ruin the warranty) or solder the old one back in.
(though the replacement is much smaller in size, is that safe?)

Or:
Send it back and have it repaired. I don't want a refund because these are impossible to find and I like it.

What to do?
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Re: loose, red hot resistor - DK600 problems

Post by rhino » Thu Jun 09, 2011 8:49 pm

A blow hard enough to knock a SOLDERED resistor right off the board should be investigated. I'd send it back for repairs. 12-Watt resistors can get hot (that's the reason for ceramic). Maybe has been too hot for long enough to damage the solder joints?
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Re: loose, red hot resistor - DK600 problems

Post by snod_donkey » Thu Jun 09, 2011 10:03 pm

Its very possible its just heat over the years has caused dry joints. I wouldnt just rest it in place and use it as that could cause more damage. Solder it back in place... leave it on and test it for a while... if no smoke then thats a good sign... if smoke then you have a problem

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Alex E
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Re: loose, red hot resistor - DK600 problems

Post by Alex E » Thu Jun 09, 2011 10:17 pm

Okay. They also gave the the okay to solder it back and I can still have them work on it if I need to. Thanks guys.

If I leave the ceramic coverings off the legs is that okay? I think they're a heat sink.
And if I order a new resistor, they're much smaller. Is that still safe?
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snod_donkey
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Re: loose, red hot resistor - DK600 problems

Post by snod_donkey » Thu Jun 09, 2011 10:31 pm

Alex E wrote:Okay. They also gave the the okay to solder it back and I can still have them work on it if I need to. Thanks guys.

If I leave the ceramic coverings off the legs is that okay? I think they're a heat sink.
And if I order a new resistor, they're much smaller. Is that still safe?

the old one will be fine as it is as lomg as its not burnt out. If you do replace it maybe get one thats a bit higher wattage and size to allow the heat to disipate a little better. Not a good idea to go smaller if its already getting hot

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Re: loose, red hot resistor - DK600 problems

Post by gearfixer » Fri Jun 10, 2011 12:18 pm

I would leave it on for 24 hours after you get a new resistor soldered in or use the old one if it is in good shape. If it still works after that you should be safe.
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Re: loose, red hot resistor - DK600 problems

Post by EdGs » Fri Jun 10, 2011 4:23 pm

The ceramic parts over the legs are probably sleeves that are more for insulating the leads and to keep the resistor spaced off the circuit board so the heat generated can dissipate withot getting the board hot.

Hopefully the are just mixed in with the packing stuff, etc. I do believe that they are available through most suppliers.

Good luck with the repairs.

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