Korg Trident MKI Problem

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Korg Trident MKI Problem

Postby TofuHero » Thu Jul 25, 2013 1:22 am

Hello all,

Disclaimer, I'm not well-versed in electronics or any of the sort, but I'll be as detailed as possible.

I recently received a Korg Trident MKI from Ko of Modeless Factory. Appearance-wise, the unit looks fantastic. Unfortunately to my despair, the Trident will not start up when I flick the power switch, no LEDs turn on and the unit does not produce any sound. I have unscrewed the front panel to take a look at the board connections to see if any of them are loose or if any of the fuses have blown. As far as I can tell, there aren't any clear disconnections or poorly soldered wires around the power switch and input. The fuses also appear to be intact since I can see a thin wire running through the length of the glass tubes in each of them. The only particular thing I notice is that when I turn the unit on, one and only one particular black chip on the KLM-297 Power Supply board gets very hot. It is labelled A7815 UC8346 KOREA. A little search on the net tells me this is a +15V regulator. According to the original schematics I found online, a UPC 14315 +ve regulator is labelled at the same location instead.

Putting all this together, does anyone have a clue what could possibly be wrong? I'm a little disappointed that I can't hear this beauty right away! Thanks in advance.
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Re: Korg Trident MKI Problem

Postby madtheory » Thu Jul 25, 2013 8:33 am

Yes, this is a very nice synth, I always liked the brass especially. Apparently AIR like this synth a lot too.

Do you trust the vendor? If the answer is yes, then it was working when he shipped it. Am impact during shipping has caused a fault. That is the start of the diagnosis. So visibly poor solder joints will not be your problem.

The only way to test a fuse is with a continuity tester. A fuse can look OK but occasionally they can go open circuit under the caps, right at the solder joint. Can happen in shipping, so it is not an indication of a fault. So do that first. Disconnect power when testing!!

Don't worry about the part number, that's not a problem. Regulators do get hot, that's normal. The question is "how hot?". I'm not familiar with the Trident PSU. IIRC a heatsink was added on the MKII, so maybe that is what's required for your MkI? If that's the case, vendor should've been aware that your synth had an issue. Disclaimer: I'm speculating here, I have not studied the schematics.

So contact the vendor, he should be able to help or refund you ex shipping.
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Re: Korg Trident MKI Problem

Postby vin14 » Thu Jul 25, 2013 12:56 pm

I can't be of much help, but I can confirm that the Trident Mk1 gets very hot in the general area where the flex is connected, hence the change on the Mk2 as had already been mentioned.

From what I've read here and elsewhere that vendor is sound, so surely the best bet is to get in touch with them, they're bound to know what the likely cause is.
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Re: Korg Trident MKI Problem

Postby nathanscribe » Thu Jul 25, 2013 4:26 pm

At the risk of being patronising, as it's not clear from your original post, just confirm the synth is set up to function on the working mains supply voltage of your location. More than a few mistakes have been made of this nature :)
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Re: Korg Trident MKI Problem

Postby sam » Fri Jul 26, 2013 9:15 pm

Having fixed 2 tridents....This problem will certainly be bad solder joints on the main board where the battery is.

You really have to know what your doing though...Good soldering required.
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