Did I do somthing wrong?

[feyrerm]

I cant figure out why the output is so low on a pair of p2p wired lm3875's. The wiring seems correct and the lightbulb does not even flicker on the tester. The PS is 300vac 25. I checked the VDC on the rectifier and its a solid 27v on each line. there is sound but it is very low and has trouble driving a 40w 8 ohm load.

Here are some pictures. Any help would be great.

Thanks

[lanchile]

Originally Posted by feyrerm

I cant figure out why the output is so low on a pair of p2p wired lm3875's. The wiring seems correct and the lightbulb does not even flicker on the tester. The PS is 300vac 25. I checked the VDC on the rectifier and its a solid 27v on each line. there is sound but it is very low and has trouble driving a 40w 8 ohm load.

Here are some pictures. Any help would be great.

Thanks

Well, first what is the value of the potentiometerthere!
and someone correct me if I am wrong here but if you have 25vac on the secondaries you should get over 30 vdc after rectifiers.

[feyrerm]

Thanks for the reply. I was mistaken the rectifier puts out a solid 37.2 -/+. The green wire coming from the pot goes to signal ground. Is this not the proper connection?

[lanchile]

Originally Posted by feyrerm

Thanks for the reply. I was mistaken the rectifier puts out a solid 37.2 -/+. The green wire coming from the pot goes to signal ground. Is this not the proper connection?

ok.Now what is the value of your potentiometer 10k, 25k, 50k, 100k......

[feyrerm]

25k I just picked up a 100k to try thinking this might be the problem. Also I am driving it directly from a ps1 1001 model. Could the source be the issue?

[lanchile]

Originally Posted by feyrerm

25k I just picked up a 100k to try thinking this might be the problem. Also I am driving it directly from a ps1 1001 model. Could the source be the issue?

25k or 50k are fine but 100k is too high! Get a cd player and try.also make sure all those wires hanging out do not get shorted.

[feyrerm]

OK so I hooked up a source with a volume control (Ipod). With this source there is more power than I would have ever thought. With this being the case is it my pot or my source? I was oping to mod the PS1 and use it as the permanent audio source in this system, but if the problem is not the pot than I will need to build a preamp to go with it.

Thanks again for the help!

[lanchile]

Originally Posted by feyrerm

OK so I hooked up a source with a volume control (Ipod). With this source there is more power than I would have ever thought. With this being the case is it my pot or my source? I was oping to mod the PS1 and use it as the permanent audio source in this system, but if the problem is not the pot than I will need to build a preamp to go with it.

Thanks again for the help!

Ok, if you are using you Ipod as the source with the ipod volume all the way up and you are getting enough power. the problem is not your integrated amp! the problem is with the source you connected before.if I were you I would leave the amp as integrated (with the 25k or 50k pot).leave the volume of your Ipod all the way up and you adjust the volume in your amp only.Good luck buddy!

PS: leave the volume of your Ipod all the way up and then adjust the volume from your amp....up and down and if everything is fine.............your integrated amp is fine!!!

[wwenze]

Can you post the schematics with values?

[feyrerm]

The schmatic is the one right off the nationals website. the parts are from Peter Daniels commercial gainclone site.

# Part Name/Description Digikey Part Number
2 LM3875TF LM3875TF-ND
4 1500uF 50v Panasonic FC Capacitor P10334-ND
4 22.1k ohm resistor (min quantity = 5) PPC22.1KXCT-ND
2 680 ohm resistor (min quantity = 10) P680BBCT-ND
2 220 ohm resistor (min quantity = 5) PPC20.0KXCT-ND
8 On Semiconductor MUR860 fast diodes MUR860OS-ND
2 4.7uF 50v Panasonic FC Capacitor P10315-ND