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 Forum index » DIY Hardware and Software » Circuit Bending
Roland TR-707 ??
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misjah



Joined: Aug 21, 2010
Posts: 2
Location: naisus
PostPosted: Sat Aug 21, 2010 7:37 am    Post subject: Reply with quote  Mark this post and the followings unread
Hello all! I just got 707, really bad condition but I fixed most of the stuff (power supply, jumper cables between boards, sliders etc.) The only thing that isn't working is Hi HAT. No sound at all ( both master and separate OUT). Buttons are OK, slider POT is also fine. What else should I check here? (I hope it's not bad ROM)
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electri-fire



Joined: Jul 26, 2006
Posts: 536
Location: Dordrecht NL
Audio files: 4
G2 patch files: 4
PostPosted: Sat Aug 21, 2010 8:02 am    Post subject: Reply with quote  Mark this post and the followings unread
misjah wrote:
Hello all! I just got 707, really bad condition but I fixed most of the stuff (power supply, jumper cables between boards, sliders etc.) The only thing that isn't working is Hi HAT. No sound at all ( both master and separate OUT). Buttons are OK, slider POT is also fine. What else should I check here? (I hope it's not bad ROM)


If worked on TR-505, not 707 , but they're similar so ...

Are the individual outs take from near a row of transistors? These would be the VCAs. You could check the signals back from the Hihat transistor. Maybe the Hihat transistor is dead.
Connect the signal prior to the transistor to another transistor that works to see if you get a Hihat going on another channel.

These VCA transistors need an envelope control voltage. These come from a row of capacitors. You can superimpose the Envelope voltage on another channel, see if it works.

Further upstream there's separate gates that start an oscillator driving a counter to generate adresses to read each sound. Here it gets complicated, If I remember corectly the adresses and readouts are multiplexed ( combined) into a single data stream, and demultiplexed to send the appropriate data to their appointed outputs.

But your most likely candidate is the VCA transistor I think.
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misjah



Joined: Aug 21, 2010
Posts: 2
Location: naisus
PostPosted: Sun Aug 22, 2010 11:34 am    Post subject: Reply with quote  Mark this post and the followings unread
Thanx for quick response. There are 5 M5218L dual op amps for 10 sliders. I'll try to swap them first to see if this one is dead. This is on volume board.
I did a quick transistor check on main (voicing) board and they all seem OK.

Edit: nope, that didn't work....
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Lorenzo



Joined: Nov 09, 2008
Posts: 375
Location: Trieste - Italy
PostPosted: Wed Dec 23, 2015 11:10 am    Post subject: Reply with quote  Mark this post and the followings unread
Although I finished modifing the tr-707 five years ago, a few months after starting this thread, only now I drilled the box to place the potentiometers and the patch-bay... And I don't even want to know what was going on with me and my tr-707...

https://www.instagram.com/p/_MTfM3gDxn/
https://www.instagram.com/p/_MWLKIAD3H/
https://www.instagram.com/p/_Mc-GzgD1g/

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Posted Image, might have been reduced in size. Click Image to view fullscreen.

Posted Image, might have been reduced in size. Click Image to view fullscreen.
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starbearer76



Joined: Jul 28, 2016
Posts: 1
Location: chicago
PostPosted: Thu Jul 28, 2016 7:25 pm    Post subject: Reply with quote  Mark this post and the followings unread
Is anyone still on here I hope? ha ha ha... So What about pitch controlling the cymbals? I don't see pins listed for that. Help!! As I've drilled a hole for it thinking that there was indeed a pin for it Embarassed . I know there is a decay control mod for it which I plan on doing but I want pitch control as well.

Thank you ahead of time if someone is able to help with that.

cheers!!
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Lorenzo



Joined: Nov 09, 2008
Posts: 375
Location: Trieste - Italy
PostPosted: Wed Aug 31, 2016 1:25 am    Post subject: Reply with quote  Mark this post and the followings unread
starbearer76 wrote:
Is anyone still on here I hope? ha ha ha... So What about pitch controlling the cymbals? I don't see pins listed for that. Help!! As I've drilled a hole for it thinking that there was indeed a pin for it Embarassed . I know there is a decay control mod for it which I plan on doing but I want pitch control as well.

Thank you ahead of time if someone is able to help with that.

cheers!!


Dacay control mod is quite easy...
For pitch mods you have to read this thread, it is not as simple as drill a hole...

anyway...
On IC30(gate Array) the relevant pins are:
Pin 56: Bass Drum
Pin 57: Snare Drum

Pin 59:Low Toms
Pin 60:Mid Toms
Pin 61:High Toms
Pin 62:High Hat
Pin 63:Rimshot/Cowbell
Pin64:Handclap/Tamborine

You have to desolder this pin and replace it with a new "clock oscillator" to controll the gate array...
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