Just get a piece of steel galvanize sheet metal from the hardware store or at the local scrap yard thats a bit larger than the board. If its a magnetic induction sort of thing placing it between the board and tranny that should answer that question. Just be sure to insulate the board from the sheet steel or it'll be the 4th all over again!
I see you used crimps so double check all those to be sure they are good and tight... or better yet, solder them if they're not already. Also, increase the wire gauge or use multiple runs between the star ground point and the power supply ground. I'd use at least a stranded number 6, or the multiple wire equivelent of that size. Better yet move that whole star grond setup over to the actual power supply ground rail. Your input wire should be twisted when its in that close of proximity to the tranny. Twisting it will cause it to have a self cancelation effect and it won't pick up any hum.
Also, if you have a scope check the level of ripple on the rails and make sure that its not excessive. Other than these and the other members suggestions a complete rebuild moving the caps to between the tranny and board might be in order.
. When the hum is gone you'll have a really great amp!!
Mark
I see you used crimps so double check all those to be sure they are good and tight... or better yet, solder them if they're not already. Also, increase the wire gauge or use multiple runs between the star ground point and the power supply ground. I'd use at least a stranded number 6, or the multiple wire equivelent of that size. Better yet move that whole star grond setup over to the actual power supply ground rail. Your input wire should be twisted when its in that close of proximity to the tranny. Twisting it will cause it to have a self cancelation effect and it won't pick up any hum.
Also, if you have a scope check the level of ripple on the rails and make sure that its not excessive. Other than these and the other members suggestions a complete rebuild moving the caps to between the tranny and board might be in order.
. When the hum is gone you'll have a really great amp!!Mark
ok, i have great access to all sorts of bits and pieces. getting some galvanized steel is no problem.
as far as the ripple, i have a multimeter that has a bar graph thing at the bottom and when i measure the dc voltage from a power supply, if there is heavy ripple (ie - no caps), it fluctuates heavily, but as caps are added, it evens out... with this PS, its almost dead steady.
dont know if thats what you meant or not.
oh, and the board is actually attached to the metal plate with nylon spacers. i try and use nylon in most places where heat isnt an issue. its just easier than remembering to isolate it. ill give that a go tomorrow. i hope that cures it.
as far as the ripple, i have a multimeter that has a bar graph thing at the bottom and when i measure the dc voltage from a power supply, if there is heavy ripple (ie - no caps), it fluctuates heavily, but as caps are added, it evens out... with this PS, its almost dead steady.
dont know if thats what you meant or not.
oh, and the board is actually attached to the metal plate with nylon spacers. i try and use nylon in most places where heat isnt an issue. its just easier than remembering to isolate it. ill give that a go tomorrow. i hope that cures it.
As highbias said try to put a peace of steel betwen tranny and amp. Try to put as close as possible the input wire to respectiv ground amp wire as on the picture under (blue wires are ground wires)
Before this layout input wire were 4 cm spaced by a plastic plate from grounds wires and the amp was humming à little. Since this layout it sound quite dead on humming.
Marc
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Before this layout input wire were 4 cm spaced by a plastic plate from grounds wires and the amp was humming à little. Since this layout it sound quite dead on humming.
Marc
Banned
Joined 2002
ok, so ive thought this over a bit. (i just dont want to go opening it up and tinkering becuase every wire is within a 1/2" of where it shold be, so nothing will be moving without rewiring...
IF it is a problem ive got stuff too close together, could i use any ferrous metal (ie - copper, steel, etc...) around and on top of transformer (like a small cage or box), to stop the problem? this is MUCH MUCH easier for me than to moving things around. the layout is actually quite fixed if you look. wires follow a nice flow and progression through the amp, and everything is short as possible.
i woud much rather fix the problem that way than by moving it. plus, with the size of the cap bank and its location, i only have so much room to move the two away from eachother.
IF it is a problem ive got stuff too close together, could i use any ferrous metal (ie - copper, steel, etc...) around and on top of transformer (like a small cage or box), to stop the problem? this is MUCH MUCH easier for me than to moving things around. the layout is actually quite fixed if you look. wires follow a nice flow and progression through the amp, and everything is short as possible.
i woud much rather fix the problem that way than by moving it. plus, with the size of the cap bank and its location, i only have so much room to move the two away from eachother.
the local surplus shop by me has copper panels that are a little bit nasty looking (it is copper...) but they sell for a few bucks a sheet (12" x 12" roughly) that i can buy and quickly cut up and make into a box to surround the xformer. either that or i could use stainless steel, i have a lot of hardware stores and lumber yards around.
Just a piece of galvanized sheet metal will work fine for the test. If the hum is reduced with the sheet metal in place then I'd reccomend a complete re-build where place the caps between the board and tranny, mounting the board in the back of the amp closest to the input and output terminals. This should give you some good isolation. I've also read that wrapping a toroid with steel around its outside will help reduce stray magnetic fields quite a bit. I remember seeing some toriods made with that steel band around them. Potting the tranny into a steel can would be the best way to shield it though.
Mark
Mark
i found some steel at the hardware store by me. i grabbed a magnet from the shelf and tested it, it is magnetic. i will give that a go later tonight and see what i find. i also gave the problem to a friend of mine who helps design amps for a higher end company here in boulder. he gave the same suggestion and thought that a plate around the transformer could eliminate the problem. we will see.
so an update:
i cut a piece of steel and mounted the PCB on it. (like ive said before, its not practical to move the PCB around, its very much anchored by the wires at this point).
that did absolutely nothing. being that i had it on aluminum right above the xformer, and now i have a steel plate, i dont think that could be the problem. my friend basically told me that if that didnt at least affect it, its not the cause. sounds logical enough.
so... im now moving all the ground wires to the ground plane on the cap bank, hoping thats where its coming from. if this doesnt work, it looks like i might have to take highbias' advice and rebuilt the whole thing. i would put caps in middle tranny on one side, and board on the other. however, it might not work out because i dont want really long wires running to the fets
time will tell. im almost done moving the wires. i just like to take breaks inbetween rewiring things because then i can get a fresh look at it all. i hate just moving wires and rewiring and then kicking it on. i always watch tv or surf the net before, so when i come back down, its like "wait, what is that?"
i cut a piece of steel and mounted the PCB on it. (like ive said before, its not practical to move the PCB around, its very much anchored by the wires at this point).
that did absolutely nothing. being that i had it on aluminum right above the xformer, and now i have a steel plate, i dont think that could be the problem. my friend basically told me that if that didnt at least affect it, its not the cause. sounds logical enough.
so... im now moving all the ground wires to the ground plane on the cap bank, hoping thats where its coming from. if this doesnt work, it looks like i might have to take highbias' advice and rebuilt the whole thing. i would put caps in middle tranny on one side, and board on the other. however, it might not work out because i dont want really long wires running to the fets
time will tell. im almost done moving the wires. i just like to take breaks inbetween rewiring things because then i can get a fresh look at it all. i hate just moving wires and rewiring and then kicking it on. i always watch tv or surf the net before, so when i come back down, its like "wait, what is that?"
ok, third post in a row...
but im happy now. and not only that, but ive learned a TON.
so, i moved all the wires to a common ground that was on the actual cap bank. as you can see from the pictures, i had a small metal bar that held the star ground, and a small wire that connected that star ground to the cap bank. this turned out to be the problem! attached is a picture of the tiny little wire that created a problem that took hours to fix.
in the process, i accidentally broke off two pads on the circuit board, so now the wires are just soldered directly to a resistor. plus, i noticed my transformer hums too.
im going to try and get a new board to mount everything on, in the future use smaller guage stranded wire instead of solid core, and get bigger rubber pads for the transformer.
i was informed that using the tiny little pads they give you is nice, but if you can get thicker rubber pads it helps a whole lot with noise.
all in all, it works well. however, when i broke off the pads on the PCB, i fried one of my test speakers. it still works, but it measures 0.7 ohms and it doesnt ever get very loud at all. so, i need new shop speakers.
but, it works and after some more thorough testing and a proper rewire, i will hook it up to my main speakers for a listen.
thanks everyone, without this forum, i would own all aiwa gear because i cant affor much better (well, not really), and i sure as hell wouldnt be able to build this stuff without everyone here.
edit:
this is all it took to make my day hell
http://www.cowanrg.mesanetworks.net/projects/images/aleph3/aleph3_11.jpg
but im happy now. and not only that, but ive learned a TON.
so, i moved all the wires to a common ground that was on the actual cap bank. as you can see from the pictures, i had a small metal bar that held the star ground, and a small wire that connected that star ground to the cap bank. this turned out to be the problem! attached is a picture of the tiny little wire that created a problem that took hours to fix.
in the process, i accidentally broke off two pads on the circuit board, so now the wires are just soldered directly to a resistor. plus, i noticed my transformer hums too.
im going to try and get a new board to mount everything on, in the future use smaller guage stranded wire instead of solid core, and get bigger rubber pads for the transformer.
i was informed that using the tiny little pads they give you is nice, but if you can get thicker rubber pads it helps a whole lot with noise.
all in all, it works well. however, when i broke off the pads on the PCB, i fried one of my test speakers. it still works, but it measures 0.7 ohms and it doesnt ever get very loud at all. so, i need new shop speakers.
but, it works and after some more thorough testing and a proper rewire, i will hook it up to my main speakers for a listen.
thanks everyone, without this forum, i would own all aiwa gear because i cant affor much better (well, not really), and i sure as hell wouldnt be able to build this stuff without everyone here.
edit:
this is all it took to make my day hell
http://www.cowanrg.mesanetworks.net/projects/images/aleph3/aleph3_11.jpg
Cool! When I first saw your picture of the amplifier , that's what struck me the most as "wow, that's a thin wire for a class a amp" . Glad it worked out for you.
I am in the middle of making a new chassis and will take extra measures in grounding everything to make sure its completely silent
I am in the middle of making a new chassis and will take extra measures in grounding everything to make sure its completely silent
yeah, i really had no idea about grounding something like that...
as far as the wire goes, its all 16 and 14 guage! i thought that would be enough. however, when i rewire it, ill use nice stuff. its gotta be taken all apart so i can duplicate a second channel anyways. so ill just clean it up and do some rewiring.
as far as the wire goes, its all 16 and 14 guage! i thought that would be enough. however, when i rewire it, ill use nice stuff. its gotta be taken all apart so i can duplicate a second channel anyways. so ill just clean it up and do some rewiring.
the saga continues!
so, i got it "working" last night. well, turns out its NOT working. i thought my speaker was blown (it most likely is), so i wasn't giving it much volume at first. i kept the pre-amp on minumum. i heard music, it was buzz free, i rejoiced.
however, it was too soon. everything appears to be working fine now, except for the fact it doesnt really amplify! the music is only VERY faint. for instance, when my air conditioner turned on, i couldnt hear it anymore, except for when i had my ear right up to the speaker. im sure its the amp because i have an 8-ohm dummy load that doesnt measure a thing. i hook it up, hook up a meter, crank it on, and the most i can get is 1v, or .125 watts.
so, what happened now? im a dummy when it comes to electronics, but is the output devices blown or something? if so, thats a relatively easy fix, i have like 8 matched sets.
any advice people?
edit:
to add, the heatsinks are getting very warm as well. its normal temp, so i can tell power is getting somewhere, its just not amping the signal.
so, i got it "working" last night. well, turns out its NOT working. i thought my speaker was blown (it most likely is), so i wasn't giving it much volume at first. i kept the pre-amp on minumum. i heard music, it was buzz free, i rejoiced.
however, it was too soon. everything appears to be working fine now, except for the fact it doesnt really amplify! the music is only VERY faint. for instance, when my air conditioner turned on, i couldnt hear it anymore, except for when i had my ear right up to the speaker. im sure its the amp because i have an 8-ohm dummy load that doesnt measure a thing. i hook it up, hook up a meter, crank it on, and the most i can get is 1v, or .125 watts.
so, what happened now? im a dummy when it comes to electronics, but is the output devices blown or something? if so, thats a relatively easy fix, i have like 8 matched sets.
any advice people?
edit:
to add, the heatsinks are getting very warm as well. its normal temp, so i can tell power is getting somewhere, its just not amping the signal.
set your multimeter to DCV, clip your negative probe (black) to a good ground and measure DC voltages called out on NP's Aleph 3 schematic by touching positive probe (red) on the test points. To measure voltage drops put probes across parts to be measured. Example, on Drain-Source or Gate-Source. Be careful where you stick 'em...I usually wrap tape around metal part of probes just leaving the tips exposed.
Yes, The metal under the PCB was really an experiment to cinfirm if magnetically induced hum was the root of the ptoblem. Its obviously not though. Measure all the voltage readings indicated on the schematic as Blues indicated in his post above and let us know what you read. I'll check back later tonight.
Mark
Mark
yeah, ill get to that tonight when i get home from work.
i think it might be an issue with the PCB. as i stated, in the whole ordeal of getting rid of the hum, ive ruined a couple of pads on the board. the iron was set too hot and i didnt realize it.
i have another board that i will most likely stuff and replace the original now that the hum is gone. hopefully that will cure the situation.
im starting to get a little tired of it not working though
i think it might be an issue with the PCB. as i stated, in the whole ordeal of getting rid of the hum, ive ruined a couple of pads on the board. the iron was set too hot and i didnt realize it.
i have another board that i will most likely stuff and replace the original now that the hum is gone. hopefully that will cure the situation.
im starting to get a little tired of it not working though
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.