Strange Hum on Sustainor

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Sunburst
Posts: 117
Joined: Sun Mar 30, 2014 12:46 am

Re: Strange Hum on Sustainor

Postby Sunburst » Thu May 18, 2017 5:29 pm


dreamevil
Posts: 20
Joined: Mon Nov 16, 2015 7:11 pm

Re: Strange Hum on Sustainor

Postby dreamevil » Thu May 18, 2017 5:50 pm

Thank you. I'm trying to find a site that has standart post. Mouser send the parts for $20. Other component sites (including eBay) has only payment with Paypal and unfortunately Paypal stopped working in Turkey. I'm really stucked on this situation. Insisting on rockman stuff, have tried IIB, X100, Sustainor and Chorus/Delay. (god at least there is no problem on Chorus/Delay) But i need to use it with minimal noise.(like David's ;) )

Sunburst
Posts: 117
Joined: Sun Mar 30, 2014 12:46 am

Re: Strange Hum on Sustainor

Postby Sunburst » Thu May 18, 2017 6:25 pm

Dreamevil,

There are several sites out there (Mouser, Digi-Key, etc.) but some of the vintage Rockman parts are now hard to find (if not impossible to find). Good luck!

Very respectfully,

Sunburst

GuitarBuilder
Posts: 164
Joined: Sat Aug 30, 2014 7:14 pm

Re: Strange Hum on Sustainor

Postby GuitarBuilder » Wed May 24, 2017 2:14 pm

dreamevil wrote:Thank you so much. I'll try these steps as soon as possible. But on the other hand, i'm trying to find a 2N4338 Jfet replacement anyway.


Please don't touch the JFET unless you've tried all other suggestions. Some of them are hand selected and matched to the circuitry.

dreamevil
Posts: 20
Joined: Mon Nov 16, 2015 7:11 pm

Re: Strange Hum on Sustainor

Postby dreamevil » Sat May 27, 2017 11:39 pm

Thanks for the advices. I applied every step to the unit. General noise reduced but the touching hum still exists. When touching from front panel or upper still strange Hum exists. Don't know what to do...

GuitarBuilder
Posts: 164
Joined: Sat Aug 30, 2014 7:14 pm

Re: Strange Hum on Sustainor

Postby GuitarBuilder » Mon May 29, 2017 2:56 pm

Do you have an oscilloscope?

dreamevil
Posts: 20
Joined: Mon Nov 16, 2015 7:11 pm

Re: Strange Hum on Sustainor

Postby dreamevil » Thu Jun 01, 2017 11:00 pm

I don't. Here's another thing about it, when the Smart Gate button ON, the hum occurs easily.

dreamevil
Posts: 20
Joined: Mon Nov 16, 2015 7:11 pm

Re: Strange Hum on Sustainor

Postby dreamevil » Fri Jun 02, 2017 9:31 pm

At last i unsoldered it carefully. But it has 3 models on it. It might have been replaced by the seller i bought i think.
Here's the codes on it.
Y-2094
A8 Y-2094
SF 3114
You do not have the required permissions to view the files attached to this post.

GuitarBuilder
Posts: 164
Joined: Sat Aug 30, 2014 7:14 pm

Re: Strange Hum on Sustainor

Postby GuitarBuilder » Mon Jun 05, 2017 10:29 pm

It may indeed have been replaced before you bought it.

Put in the real thing:
http://www.mouser.com/ProductDetail/Vishay-Semiconductors/2N4338-E3/?qs=vnwGVgFuQiZE5yHZhC8V6w%3D%3D

dreamevil
Posts: 20
Joined: Mon Nov 16, 2015 7:11 pm

Re: Strange Hum on Sustainor

Postby dreamevil » Wed Jun 07, 2017 4:45 pm

Have been studying on Sustainor for days. After removing the Gate part of the pcb, i saw some solder problems. Fixed them and resolder the 2N4338 part again carefully. But strange thing is, when i shake the device a bit or touch any part of it strong, the strange hum still exists. And when hum occurs the error led flashes.
Now i want to check the transformer. Could anyone tell me the Output Voltage of the transformer? And if i need to replace the transformer, what should be the exact specs ? Or any other advices to check ?
Thanks.