Hi,
increase the value of the dropping resistor.
Check the resistor dissipation and select accordingly.
increase the value of the dropping resistor.
Check the resistor dissipation and select accordingly.
Another question,
When measuring dc output does the amp need to be connected to a preamp? I'm not getting any readings at all.
Thanks,
Chevy
When measuring dc output does the amp need to be connected to a preamp? I'm not getting any readings at all.
Thanks,
Chevy
Hi Chevy,
no, but the input offset will be affected by the input source. Try wiring an empty RCA with a short from ground to pin and plug this into the amp input for testing.
The DC output offset should be measurable without a load connected either, but may change when you connect a load.
If you find that removing the shorting input plug and connecting the preamp changes the output offset then some DC is leaking through to the power amp.
no, but the input offset will be affected by the input source. Try wiring an empty RCA with a short from ground to pin and plug this into the amp input for testing.
The DC output offset should be measurable without a load connected either, but may change when you connect a load.
If you find that removing the shorting input plug and connecting the preamp changes the output offset then some DC is leaking through to the power amp.
Can explain what you mean. It sort of sounds like you want me to plug in an RCA cable and then ground it out. Is this correct?
Chevy
Correct. Shorting plugs are a vital part of every builder's test equipment, and all DC tests should be made with one in place. Sometimes inputs left floating can produce strange results on testing, possibly even oscillation.
Ok I'm still not getting any readings at all. Here's what I did perhalps I'm going about it wrong.
I took an audio RCA cable and soldered a wire from the ground to the pin. Then I plugged the other end into the amp, turned amp on. I set my multimeter for DC and tried to check for dc output on the left and right speaker terminals. When that didn't work I took another RCA cable, did the same thing as above and plugged it into the other rca input on the amp and still nothing.
I'm looking for some input please as to what I'm doing wrong.
Thanks,
Chevy
I took an audio RCA cable and soldered a wire from the ground to the pin. Then I plugged the other end into the amp, turned amp on. I set my multimeter for DC and tried to check for dc output on the left and right speaker terminals. When that didn't work I took another RCA cable, did the same thing as above and plugged it into the other rca input on the amp and still nothing.
I'm looking for some input please as to what I'm doing wrong.
Thanks,
Chevy
what range is your meter set to?
you would be looking for something in the millivolt range. I think mine was around 14mV or something.
you would be looking for something in the millivolt range. I think mine was around 14mV or something.
I set my meter to 250 DCV. Could it be to high? Also the multimeter I have is an analog one. Should I have a digital one instead?
Also what I did with the RCA cables is that OK?
Thanks,
Chevy
Also what I did with the RCA cables is that OK?
Thanks,
Chevy
hahaha, no you need to set it to the lowest range it will give you a reading at... when set to 250V for full scale deflection of the needle a few mV wil not even register.
chevy2410 said:
Yeah, I think the rca cables should be ok. you just want the input shorted to give you a good stable 0 input.
250 VDC is much too high. You'll likely need to be on the lowest range. mV as I said before. If it doesn't have that low a range, you may as well get yourself a cheap digital one. It'll be handy anyways.
-Nick
Ok, I set the meter to the lowest range which is 10m DCA. Is this low enough? I still don't get any readings. Perpaps I should just go and get a digital one. This is really frustrating. I know it's some simple, but when you don't have exprience with it.... it sucks.
Chev
Chev
OK, I've got an update!
I was able to get a digital meter and was able to get a reading. The left side was 1.6 and the right .6. Now this seems odd. Shouldn't both be the same? BTW I set the meter at 200m to get these readings. Does this sound Ok?
Chevy
I was able to get a digital meter and was able to get a reading. The left side was 1.6 and the right .6. Now this seems odd. Shouldn't both be the same? BTW I set the meter at 200m to get these readings. Does this sound Ok?
Chevy
well, if those are milliamps dc, that sounds quite good.
The two sides won't neccessarily be the same. It can vary with either small differences in the chips, or other supporting components.
Either way, you shouldn't hear any difference at those levels.
I'd still hook it up to some lousy speakers you don't care about first. Always a good idea just incase you missed something and it smokes them.
-Nick
The two sides won't neccessarily be the same. It can vary with either small differences in the chips, or other supporting components.
Either way, you shouldn't hear any difference at those levels.
I'd still hook it up to some lousy speakers you don't care about first. Always a good idea just incase you missed something and it smokes them.
-Nick
Yes to was set to millivolts.
My father-in-law has a bad set of speakers he said I could use. So if I blow them he doesn't care
Chevy
Sounds just fine... forget about getting them even without servos etc... Well now you know if your output DC can't be measured on yourbig multimeter, it is negligible....
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