I don't think ROHS is mandatory here. And secondly this is going way off topic and about half the posts in this thread are you guys arguing. Sorry to be pushy but I think you've talked about the safety stuff enough. The thread was made for me to get help getting the amp running. There is a safety ground on the chassis nuff said.
You can find the datasheet here: http://www.qualtekusa.com/catalog/ac_recept/pdfs/723wx202.pdf
The power ground connection is similar to what I did in Patek amp: you can see 2 black ground wires connected centrally to copper jumper between both channel grounds. The speaker ground is connected there too (on each side). Signal ground goes to SG points on each board. This certainly helps in solving ground issues over the previous mthod where separate ground wires from rectifier board are connected to each amp board.
An externally hosted image should be here but it was not working when we last tested it.
Ok nothing I do seems to be helping here. Caps didn't fix it didn't change it at all. Changed the grounding like you did peter and that didn't fix it. I don't know what to do. I changed my input wires to some 26ga magnet wire like someone recommended the static got lower but the hum is still there quite bad.
then work on your problem... shorted input = 0v input.
No shorted input = incomplete circuit.
My 2 cents is that on a gainclone you are wasteing your time with those seperate little input wires (left and right channel). How many sources do you have with split grounds?
I would also, if faced with your symptoms, go for shieled input cables, ensure no power cables runover your interconnects etc.. lastly I would install the 300pf cap on the inputs, and even maybe about 12pf right over the rca terminals.
No shorted input = incomplete circuit.
My 2 cents is that on a gainclone you are wasteing your time with those seperate little input wires (left and right channel). How many sources do you have with split grounds?
I would also, if faced with your symptoms, go for shieled input cables, ensure no power cables runover your interconnects etc.. lastly I would install the 300pf cap on the inputs, and even maybe about 12pf right over the rca terminals.
You think maybe this radioshack wire I used in the PSU and other connections could be part of the problem? It said somethign about it being reclaimed wire on the packaging. Maybe its just that horrible of wire? Other then that I don't know what else could be causing it. I know when I switched from the stranded wire to the magnet wire on the inputs the static went down a lot.
Hi Dougie085,
In my view, you should be using the proper gauge of stranded wire to connect your amplifier up. You are dealing with AC currents that can reach a high frequency.
I suspect that a minor error in your grounding may be the cause. You should have a good look at the grounding that Peter uses. Try to make yours look the same. Remember that you should look at wire as if they are resistors with inductance.
-Chris
In my view, you should be using the proper gauge of stranded wire to connect your amplifier up. You are dealing with AC currents that can reach a high frequency.
I suspect that a minor error in your grounding may be the cause. You should have a good look at the grounding that Peter uses. Try to make yours look the same. Remember that you should look at wire as if they are resistors with inductance.
-Chris
Dougie085 said:
It seems like you didn't exactly do it.
A 300pf cap (that's picofard, 200pf is fine too) should be connected between pins 7 and 8 of each chip (that is noninverting and inverting chip input).
You cannot evaluate the amp performance with nothing connected: it will always hum and pick up interferences. To do it properly, RCA inputs should be shorted (input connected to ground); then you can say how much the amp hums or if static is being picked up.
Also, looking at your initial picture, you have signal wires tangled together with output wires. While that may not be a problem, it's always better to have inputs and outputs somewhat separated, especially with chip amps.
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