Inverted input?

Inverted input?

Posted by slownlo (A) on August 18, 2011 at 09:00:08

I just finished a homebrew class A amp based on the ZEN 4. I bought the PCBs on ebay. they are very thik with nice traces. good quality boards...

there is a single 300VA toroid feeding a single bridge rectifier. the filter cap for each channel is being fed from it (50VDC).

after bringing it all up slow on a variac, I biased it up, etc...
voltages checked out on both boards. good to go...

(OFF) I plugged in a source to the RCA's and connected some cheap sony 3 ways I used to test amps with (ON)...but only the left channel played (sounds nice!)...

(with the left RCA still in and source signal going)
after some probing (using SAFETY) and rechecking the the right PCB for solder bridges, etc...I touched ONLY THE INSIDE PIN pin of the RCA male plug (from the source) to the ground part of the right PCB RCA chassis plug and voila...music from the right...loud and clear...

if I ground/signal both inputs, only the left plays. when I remove the right RCA and touch the inside of it to the ground of the chassis rca..both channels play...

any thoughts as to why this is happening?

This post is made possible by the generous support of people like you and our sponsors:

Topic - Inverted input? - slownlo 09:00:08 08/18/11 (21)

Its always the obvious.... - slownlo 18:15:02 08/19/11 (7)

Glad you got it straight. - Detailman 20:45:04 08/19/11 (6)

If you get the gumption... - slownlo 05:26:15 08/20/11 (5)

Thanks for the tip on Par-Metal - Detailman 16:30:21 08/21/11 (4)

Tempermental F5? - slownlo 18:11:42 08/21/11 (3)

Haven't gotten all the info on the Zen yet but - Detailman 21:39:32 08/22/11 (2)

RE: Haven't gotten all the info on the Zen yet but - slownlo 05:36:44 08/23/11 (1)

RE: Haven't gotten all the info on the Zen yet but - Detailman 10:31:24 08/23/11 (0)

Seems like the wires on the channel have to be reversed - Detailman 10:19:18 08/19/11 (2)

RE: Seems like the wires on the channel have to be reversed - slownlo 12:06:02 08/19/11 (1)

Just ohm out the jack as that could be - Detailman 20:41:49 08/19/11 (0)

RE: Inverted input? - Bob in Alberta 13:23:06 08/18/11 (5)

RE: Inverted input? - slownlo 16:39:02 08/18/11 (4)

RE: Inverted input? - Tony Lauck 11:33:43 08/19/11 (0)

RE: Inverted input? - djk 18:13:01 08/18/11 (2)

RE: Inverted input? - slownlo 19:44:11 08/18/11 (1)

I think you had it right the first time- - cdb 11:11:25 08/19/11 (0)

RE: input wiring? - cdb 10:01:29 08/18/11 (3)

RE: input wiring? - slownlo 11:02:18 08/18/11 (2)

RE: input wiring? - cdb 12:37:19 08/18/11 (1)

RE: input wiring? - slownlo 13:09:03 08/18/11 (0)

Post a Message!