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Circuitbenders Forum => Circuitbending discussion => Topic started by: chrisg on April 28, 2010, 07:11:52 PM

Title: TR-626 with corrupted IC chips?
Post by: chrisg on April 28, 2010, 07:11:52 PM

While bending a TR-626 there suddenly occurred what appeared to be a permanent short. I've been examining the circuitboard for soldering drops and the likes for about a million of times without finding anything which could cause the short. I even tried to de-solder all wires and the IC15 but without any luck.

I mainly been messing with IC15 and IC5, and the unwanted bend sounds like crunchy 8bit distortion with and added resonance tone..

My question is therefore if anybody know if the IC could possibly be corrupted in such a way? - or are they either dead or alive?

Any help or troubleshooting advices highly appreciated :)

Title: Re: TR-626 with corrupted IC chips?
Post by: Gleix on April 29, 2010, 06:17:51 PM

I had some IC problems with my 626. Replacing the ICs fixed the problem.

This might be of a little help: http://www.circuitbenders.co.uk/forum/index.php/topic,1060.0.html (http://www.circuitbenders.co.uk/forum/index.php/topic,1060.0.html)

How is your 626 acting?

Also, if you want any bending tips, here's my 626: http://www.circuitbenders.co.uk/forum/index.php/topic,1173.msg7405.html#msg7405 (http://www.circuitbenders.co.uk/forum/index.php/topic,1173.msg7405.html#msg7405)

And a .doc file explaining all the modifications i made: http://www.burnkit2600.com/thom/tr626/other626s/GG%27s%20Roland%20TR-626%20mods.doc (http://www.burnkit2600.com/thom/tr626/other626s/GG%27s%20Roland%20TR-626%20mods.doc)

Title: Re: TR-626 with corrupted IC chips?
Post by: chrisg on April 29, 2010, 09:46:47 PM

Thanx for the reply and bending tips breakbeatnazi and thumbs up for the amazing piece of gear you made of your 626!
Ill try to replace IC18, 19 and 24 to see if it helps - was actually soldering to a IC18 pin too so I might have fried it up..

Besides for added the distortion and resonance "tone" the machine is acting perfectly as originally intended by the Japs.

Title: Re: TR-626 with corrupted IC chips?
Post by: Gordonjcp on April 29, 2010, 11:00:59 PM

The only really interesting chip in the 626 is the big mask-programmed ROM with the samples.  The two surface-mount microcontrollers are extremely fragile and impossible to get when they break.  Be really careful.

Title: Re: TR-626 with corrupted IC chips?
Post by: chrisg on May 03, 2010, 07:56:22 PM

Hmm, tried to replace the all 4051 multiplexer ICs but the problem is still there:(

Here is what my 626 sounds like:
http://dl.dropbox.com/u/3489433/TR-626.mp3 (http://dl.dropbox.com/u/3489433/TR-626.mp3)

Any ideas anybody?

Title: Re: TR-626 with corrupted IC chips?
Post by: Circuitbenders on May 03, 2010, 09:41:57 PM

That really does sound like you've got a short on the sound ROM somewhere. Have you tried going over it pin by pin with a continuity tester on a multimeter to make absolutely sure that nothings shorted?

Title: Re: TR-626 with corrupted IC chips?
Post by: chrisg on May 04, 2010, 07:46:46 PM

You are totally right circuitbenders, it really does sounds like a short at IC15. I've been going over it with a continuity tester, together with the rest of the board - but in vein.

I'm really puzzled..

Title: Re: TR-626 with corrupted IC chips?
Post by: alienized on December 09, 2010, 10:05:24 PM

Hi,
Did you solve your issue ? I've got the exact same issue after carefully starting to bend my 626. I ran the same tests with no success...