mesak Posted August 17, 2005 Report Share Posted August 17, 2005 yo! i'm proceeding nicely with the SID - can't wait to get it up and running for real! :Pi made a power pcb for the unit (see the pics - it includes bankstick as you can see...) but when i put the synth on i got quite loud ground hum there too . is it possible that i screwed up the power connections somehow (it looks more messy than it is really) or can it be because i didn't make the optimized PSU but the basic one? i'm using original c64 power and tested the thing with two separate PSU's with same results so that should be fine. also, i have done the bypass caps on the sid & core.i'm not sure how to get rid of the hum... :(cheers Quote Link to comment Share on other sites More sharing options...
smycza Posted August 17, 2005 Report Share Posted August 17, 2005 did You try to make a short circuit between the ground and signal pins of Audio In (while being not used)I had the same problem (hum) and I still don't know why it did help :Dsmycza Quote Link to comment Share on other sites More sharing options...
Milkmansound Posted August 17, 2005 Report Share Posted August 17, 2005 it helps cause you are shorting what is usually an open jack. Most guitar amps for example will short the inputs when they are not used - thats why they crackle so loud when you are inserting the jack with the amp on and volume up. However, it may also be a faulty sid - I had a similar problem where the solution was a different sid with a fully functional filter. The filter was creating some nasty noise apparantly. You are not going to damage anything by shorting the audio in, and changing sids around and playing with a few configs until it sounds quieter. Quote Link to comment Share on other sites More sharing options...
mesak Posted August 18, 2005 Author Report Share Posted August 18, 2005 i have done the shorting. it helps a bit but the "main hum" remains wheter the ground is connected or not. also my friend is building his own sidbox at the same time and i tested my system with his SID-module - the hum is the same. so it means my sid is ok (or both sids are damaged...?)cheersps. also there's a power led included in the power pcb - now when the sid and the core are also connected the led seems to flicker to the hum frequency - i think it didn't when i first tried the power with only the led connected to it. removing the led however doesn't affect the humming... Quote Link to comment Share on other sites More sharing options...
Milkmansound Posted August 18, 2005 Report Share Posted August 18, 2005 just try a few configurations I guess, until you hear less hum. Also - what type of transformer are you using and where is it? Sometimes rotating a transformer into a new position will eliminate some hum - especially if its a torroid. Quote Link to comment Share on other sites More sharing options...
mesak Posted August 18, 2005 Author Report Share Posted August 18, 2005 ok, i will try some different configs. but is it so that you will get some serious hum anyway (ofcourse if you really crank it up you get lots of noise from everything)?i'm using the original c64 pwer supply...i just got the lcd working ok!! :D :D Quote Link to comment Share on other sites More sharing options...
Milkmansound Posted August 18, 2005 Report Share Posted August 18, 2005 personally, I can not stand that original C64 PSU - but use what you got. If TK recommends it, then its gonna be good - however, if it dies on you, replacing that internal fuse is a hellish process. I think its better to use either a dual supply, or run the modules off a single AC supply. Or breadboard something suitable. The Sid itself is gonna make some noise no matter what you do - but minimizing ground noise is essential. I still need to figure out a solution for my single 9VAC supply for both modules, and a star ground point that makes sense. Quote Link to comment Share on other sites More sharing options...
mesak Posted August 26, 2005 Author Report Share Posted August 26, 2005 ...however, if it dies on you, replacing that internal fuse is a hellish process....it's very easy with these sort of PSU's, the fuse is screwed on the back:anyway, the ground hum is the thing. more testing.... Quote Link to comment Share on other sites More sharing options...
Milkmansound Posted August 26, 2005 Report Share Posted August 26, 2005 ahh - my 2 came with the black brick type - those are much better to work with I bet - but still huge Quote Link to comment Share on other sites More sharing options...
mesak Posted August 26, 2005 Author Report Share Posted August 26, 2005 yes :Dthe one on the right (from VIC20) even has it's own power switch on it so i didn't need to make it in the midibox! 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.