seppoman Posted August 6, 2004 Report Share Posted August 6, 2004 Hi,I´ve got some problem with noise level on my new SID. Because it has only one SID inside I chose to build it with a wall wart PSU and put the in-between 7809 and the core 7805 on the back wall for cooling. When I connect the encoders to the DINs, I get digital hiss (the more encoders are connected, the worse the noise gets). what´s strange: the hiss does not occur while the encoders are not mounted on the (alu) front panel. I can´t think of a way to mount the encoders isolated from the panel or the panel isolated from the case (19"). Is there something I can do against this noise? I already tried to put capacitors across the DIN 5V supply - no effect.Thanks for any hints,Seppoman Quote Link to comment Share on other sites More sharing options...
seppoman Posted August 6, 2004 Author Report Share Posted August 6, 2004 Hi,I´ve got some problem with noise level on my new SID. Because it has only one SID inside I chose to build it with a wall wart PSU and put the in-between 7809 and the core 7805 on the back wall for cooling. When I connect the encoders to the DINs, I get digital hiss (the more encoders are connected, the worse the noise gets). what´s strange: the hiss does not occur while the encoders are not mounted on the (alu) front panel. I can´t think of a way to mount the encoders isolated from the panel or the panel isolated from the case (19"). Is there something I can do against this noise? I already tried to put capacitors across the DIN 5V supply - no effect.Thanks for any hints,Seppoman Quote Link to comment Share on other sites More sharing options...
doc Posted August 6, 2004 Report Share Posted August 6, 2004 Hi Seppoman,I´ve got some problem with noise level on my new SID. Because it has only one SID inside I chose to build it with a wall wart PSU and put the in-between 7809 and the core 7805 on the back wall for cooling. I don't understand what you mean with "in-between" thing. Can you explain a little more ?For the encoders:How did you connect te ground line of the encoders. Did you connect all encoders together on one ground line or did you connect each encoder directly to the din ground ?By the way... if you don't connect the chassis of the encoders to ground there should be no problem with them in touching the front panel, or ?Do you hear the hiss in the audio line of the SID ?What amplification after the audio out ?Did you short the audio in ?greets Doc Quote Link to comment Share on other sites More sharing options...
doc Posted August 6, 2004 Report Share Posted August 6, 2004 Hi Seppoman,I´ve got some problem with noise level on my new SID. Because it has only one SID inside I chose to build it with a wall wart PSU and put the in-between 7809 and the core 7805 on the back wall for cooling. I don't understand what you mean with "in-between" thing. Can you explain a little more ?For the encoders:How did you connect te ground line of the encoders. Did you connect all encoders together on one ground line or did you connect each encoder directly to the din ground ?By the way... if you don't connect the chassis of the encoders to ground there should be no problem with them in touching the front panel, or ?Do you hear the hiss in the audio line of the SID ?What amplification after the audio out ?Did you short the audio in ?greets Doc Quote Link to comment Share on other sites More sharing options...
seppoman Posted August 6, 2004 Author Report Share Posted August 6, 2004 Hi Doc,I don't understand what you mean with "in-between" thing. Can you explain a little more ?I meant the 7809 that is before the 7805 of the core like in http://www.ucapps.de/mbhp/mbhp_core_power_fix.pdfhere´s a picture of it:as I used the cam anyway, here are two more of the beast :)How did you connect te ground line of the encoders. Did you connect all encoders together on one ground line or did you connect each encoder directly to the din ground ?every group of 2 encoders/1 enc+2 buttons that are on one connector are on one ground (DIN).By the way... if you don't connect the chassis of the encoders to ground there should be no problem with them in touching the front panel, or ?yes, in theory - but the hiss definitely goes away when they don´t touch the front panel... ???Do you hear the hiss in the audio line of the SID ?YesWhat amplification after the audio out ?at the moment cheap active multimedia speakers.Did you short the audio in ?YesThanks,Seppoman Quote Link to comment Share on other sites More sharing options...
seppoman Posted August 6, 2004 Author Report Share Posted August 6, 2004 Hi Doc,I don't understand what you mean with "in-between" thing. Can you explain a little more ?I meant the 7809 that is before the 7805 of the core like in http://www.ucapps.de/mbhp/mbhp_core_power_fix.pdfhere´s a picture of it:as I used the cam anyway, here are two more of the beast :)How did you connect te ground line of the encoders. Did you connect all encoders together on one ground line or did you connect each encoder directly to the din ground ?every group of 2 encoders/1 enc+2 buttons that are on one connector are on one ground (DIN).By the way... if you don't connect the chassis of the encoders to ground there should be no problem with them in touching the front panel, or ?yes, in theory - but the hiss definitely goes away when they don´t touch the front panel... ???Do you hear the hiss in the audio line of the SID ?YesWhat amplification after the audio out ?at the moment cheap active multimedia speakers.Did you short the audio in ?YesThanks,Seppoman Quote Link to comment Share on other sites More sharing options...
moebius Posted August 6, 2004 Report Share Posted August 6, 2004 Hi,By the way... if you don't connect the chassis of the encoders to ground there should be no problem with them in touching the front panel, or ?yes, in theory - but the hiss definitely goes away when they don´t touch the front panel... It's a clock noise, alright? doc? Strange..I didn't figure out from the pics, how those two large supporting legs, connected to chassis of the encoders are connected? To the ground with separate wire, or getting ground connection from the case? A possible ground loop here :)Anyway - What a beauty.. Of my god ect. ect. ect.I love your design,Bye, Moebius Quote Link to comment Share on other sites More sharing options...
moebius Posted August 6, 2004 Report Share Posted August 6, 2004 Hi,By the way... if you don't connect the chassis of the encoders to ground there should be no problem with them in touching the front panel, or ?yes, in theory - but the hiss definitely goes away when they don´t touch the front panel... It's a clock noise, alright? doc? Strange..I didn't figure out from the pics, how those two large supporting legs, connected to chassis of the encoders are connected? To the ground with separate wire, or getting ground connection from the case? A possible ground loop here :)Anyway - What a beauty.. Of my god ect. ect. ect.I love your design,Bye, Moebius Quote Link to comment Share on other sites More sharing options...
seppoman Posted August 7, 2004 Author Report Share Posted August 7, 2004 Hi Moebius,It's a clock noise, alright? doc? Strange..I didn't figure out from the pics, how those two large  supporting legs, connected to chassis of the encoders are connected? To the ground with separate wire, or getting ground connection from the case? A possible ground loop here :)The encoders are connected exactly like in the schematics by TK. One DIN connector goes to 2x2 "signal pins" of the encoders, the ground pin of the DIN connector goes to the ground pins of the two encoders. I have made no connection between the ground pin and the chassis of the encoders or the supporting legs. I also checked that the encoder chassis is not connected to any pins of the encoder (Alps STEC 16) by default. So theoretically there can´t be a ground loop with the encoders. The chassis has no direct connection to any part of the cirquitry.Could the voltage regulators be part of the problem? I already had to eliminate a ground loop between the regulators and the power jack - the back part of the regulators is connected to their middle pin so the power jack had to be mounted isolated(ly?).Anyway - What a beauty.. Of my god ect. ect. ect.I love your designThanks a lot :)You have probably noticed the user interface must be a bit different to the normal MBSID ;). The nine keys on the right provide direct access to the submenus, with "return" you get directly back to the preset selection. The Menu encoder is only used for patch selection, for scrolling in the OSC and Config menus and for the patch naming menu. The switch behind the RUN/STOP key is the original shift lock switch from the C64 keyboard and toggles a relais (Power). The Commodore key toggles between normal menu soft encoder function and a "fun layer" - that´s a collection of parameters I found useful for live tweaking (the white encoder labels). This key will hopefully be illuminated from behind when "fun mode" is active - still have to find a way to do this, I thought of a "chamber" from the silver cardboard found inside the C64 lighted by a few LEDs...Seppoman Quote Link to comment Share on other sites More sharing options...
seppoman Posted August 7, 2004 Author Report Share Posted August 7, 2004 Hi Moebius,It's a clock noise, alright? doc? Strange..I didn't figure out from the pics, how those two large  supporting legs, connected to chassis of the encoders are connected? To the ground with separate wire, or getting ground connection from the case? A possible ground loop here :)The encoders are connected exactly like in the schematics by TK. One DIN connector goes to 2x2 "signal pins" of the encoders, the ground pin of the DIN connector goes to the ground pins of the two encoders. I have made no connection between the ground pin and the chassis of the encoders or the supporting legs. I also checked that the encoder chassis is not connected to any pins of the encoder (Alps STEC 16) by default. So theoretically there can´t be a ground loop with the encoders. The chassis has no direct connection to any part of the cirquitry.Could the voltage regulators be part of the problem? I already had to eliminate a ground loop between the regulators and the power jack - the back part of the regulators is connected to their middle pin so the power jack had to be mounted isolated(ly?).Anyway - What a beauty.. Of my god ect. ect. ect.I love your designThanks a lot :)You have probably noticed the user interface must be a bit different to the normal MBSID ;). The nine keys on the right provide direct access to the submenus, with "return" you get directly back to the preset selection. The Menu encoder is only used for patch selection, for scrolling in the OSC and Config menus and for the patch naming menu. The switch behind the RUN/STOP key is the original shift lock switch from the C64 keyboard and toggles a relais (Power). The Commodore key toggles between normal menu soft encoder function and a "fun layer" - that´s a collection of parameters I found useful for live tweaking (the white encoder labels). This key will hopefully be illuminated from behind when "fun mode" is active - still have to find a way to do this, I thought of a "chamber" from the silver cardboard found inside the C64 lighted by a few LEDs...Seppoman Quote Link to comment Share on other sites More sharing options...
doc Posted August 7, 2004 Report Share Posted August 7, 2004 Still strange ...BUT A GREAT DESIGN !! 8) 8)STill have no real idea on your problem. Just trying a litte bit around ...Do you have still the noise, when the regulators are not mounted to the chassis ? The chassis has no direct connection to any part of the cirquitryNo ?!. The chassis has ground connection via the regulators.Another test: Do you still have the noise, when the display is not connected to the core ? - This just to eliminate any connection from the LCD to the chassis.What happens, when you connect the chassis of a mounted encoder to ground ?Do you have the noise still, when NO midi connector is connected and perhaps with a headphone at the audio out (just to eliminate any extern loops)good luck !Doc Quote Link to comment Share on other sites More sharing options...
doc Posted August 7, 2004 Report Share Posted August 7, 2004 Still strange ...BUT A GREAT DESIGN !! 8) 8)STill have no real idea on your problem. Just trying a litte bit around ...Do you have still the noise, when the regulators are not mounted to the chassis ? The chassis has no direct connection to any part of the cirquitryNo ?!. The chassis has ground connection via the regulators.Another test: Do you still have the noise, when the display is not connected to the core ? - This just to eliminate any connection from the LCD to the chassis.What happens, when you connect the chassis of a mounted encoder to ground ?Do you have the noise still, when NO midi connector is connected and perhaps with a headphone at the audio out (just to eliminate any extern loops)good luck !Doc Quote Link to comment Share on other sites More sharing options...
seppoman Posted August 7, 2004 Author Report Share Posted August 7, 2004 Hi doc,BUT A GREAT DESIGN !!  8) 8)Thank you :)Quote:The chassis has no direct connection to any part of the cirquitry No ?!. The chassis has ground connection via the regulators.I think we have some misunderstanding about names - you used the term "chassis of the encoders" so I used "chassis" for the outside of the encoders, didn´t mean the case of the whole synthesizer.Do you have still the noise, when the regulators are not mounted to the chassis ?I already took the back wall of the case off so that only the two regulators had connection to the back wall. Interesting: the sound varied with the distance of the back wall to the rest of the case...Now I solved the problem: The noise stops when I take only one of the regulators away from the wall. Probably the small loop around the two ground wires of the regulators is closed through the back wall and acts as an antenna that picks up digital noise induced to the case by the proximity of the encoders. I still don´t totally understand this as there´s no direct connection from the encoder pins to the front panel, but the metal "chassis" of the encoders seems to help transporting clock noise to the front panel.Anyway - I will put the 7805 back on the core and give it a small heat sink - hope it doesn´t get too hot...Thank you both for your help and input,Seppoman Quote Link to comment Share on other sites More sharing options...
seppoman Posted August 7, 2004 Author Report Share Posted August 7, 2004 Hi doc,BUT A GREAT DESIGN !!  8) 8)Thank you :)Quote:The chassis has no direct connection to any part of the cirquitry No ?!. The chassis has ground connection via the regulators.I think we have some misunderstanding about names - you used the term "chassis of the encoders" so I used "chassis" for the outside of the encoders, didn´t mean the case of the whole synthesizer.Do you have still the noise, when the regulators are not mounted to the chassis ?I already took the back wall of the case off so that only the two regulators had connection to the back wall. Interesting: the sound varied with the distance of the back wall to the rest of the case...Now I solved the problem: The noise stops when I take only one of the regulators away from the wall. Probably the small loop around the two ground wires of the regulators is closed through the back wall and acts as an antenna that picks up digital noise induced to the case by the proximity of the encoders. I still don´t totally understand this as there´s no direct connection from the encoder pins to the front panel, but the metal "chassis" of the encoders seems to help transporting clock noise to the front panel.Anyway - I will put the 7805 back on the core and give it a small heat sink - hope it doesn´t get too hot...Thank you both for your help and input,Seppoman Quote Link to comment Share on other sites More sharing options...
seppoman Posted August 7, 2004 Author Report Share Posted August 7, 2004 Hi,so here are some new pictures. I found an old heatsink that is now mounted through a piece of wood. I wanted to put the 7809 on the sink but strangely the noise gets even worse when only the 7805 is in contact to the case, so my ground loop theory doesn´t work... But with 7805 on the sink everything is cool :)And here the finished box with knobs mounted - I must confess I´m a little bit proud ;)Seppoman Quote Link to comment Share on other sites More sharing options...
seppoman Posted August 7, 2004 Author Report Share Posted August 7, 2004 Hi,so here are some new pictures. I found an old heatsink that is now mounted through a piece of wood. I wanted to put the 7809 on the sink but strangely the noise gets even worse when only the 7805 is in contact to the case, so my ground loop theory doesn´t work... But with 7805 on the sink everything is cool :)And here the finished box with knobs mounted - I must confess I´m a little bit proud ;)Seppoman Quote Link to comment Share on other sites More sharing options...
doc Posted August 8, 2004 Report Share Posted August 8, 2004 You can be very proud on this !greetsDoc Quote Link to comment Share on other sites More sharing options...
doc Posted August 8, 2004 Report Share Posted August 8, 2004 You can be very proud on this !greetsDoc Quote Link to comment Share on other sites More sharing options...
Guest marr Posted August 9, 2004 Report Share Posted August 9, 2004 Seppo, what kind of thing is that on your plugs to the DIN? Shrink wrap? Quote Link to comment Share on other sites More sharing options...
Guest marr Posted August 9, 2004 Report Share Posted August 9, 2004 Seppo, what kind of thing is that on your plugs to the DIN? Shrink wrap? Quote Link to comment Share on other sites More sharing options...
seppoman Posted August 9, 2004 Author Report Share Posted August 9, 2004 Hi Marr,what kind of thing is that on your plugs to the DIN? Shrink wrap?Yes, I use shrink wrap for mostly all wires. It protects the thin wires from breaking.Seppoman Quote Link to comment Share on other sites More sharing options...
seppoman Posted August 9, 2004 Author Report Share Posted August 9, 2004 Hi Marr,what kind of thing is that on your plugs to the DIN? Shrink wrap?Yes, I use shrink wrap for mostly all wires. It protects the thin wires from breaking.Seppoman Quote Link to comment Share on other sites More sharing options...
Steven_C Posted September 4, 2004 Report Share Posted September 4, 2004 Very Nice SID64!I wish I had the patience to do that! Quote Link to comment Share on other sites More sharing options...
Steven_C Posted September 4, 2004 Report Share Posted September 4, 2004 Very Nice SID64!I wish I had the patience to do that! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.