psb sounds like hair clippers buzzing

[impsick]

ok so im having an issue. im using brians LM3886 boards. i have a 24v-0-24v ct transformer.

i read on a post of someone using a ct transformer and basically said send 24v(A) to AC1, 24v(B) to AC2, and the CT to both. so i did that and the psb seem to power up good. LED lite up, V-,PG- =34vdc, and V+,PG+=34vdc.
problem is once i hook up the amp board and power up the psb vibrates, basically sounds like hair clippers.
ha ha laugh it up. as long as you all find it amusing. jk,
i dont know what the deal is. V-psb to V-, V+psb to V+, &PG+- to corresponding pg's+-.
id appreciate the help if aanyone understood me

 

[impsick]

anybody??? got any idea??
i was messing w/ it and i pulled v- and pg+ and turned the amp on and it didnt buz. is it possible i need to switch v- and pg+ destination? **** i dont know

 

[BrianDonegan]

From PD's 3875 document...

 

[impsick]

brian would this apply to the lm3886 psboard too?

 

[CarlosT]

...is it possible i need to switch v- and pg+ destination? **** i dont know

I wouldn't think that's a good idea...both the diodes and capacitors are polarized on the rectifier board and further downstream on the amp board.

 

[jimbo1968]

pictures are definitely worth a thousand words when you are hoping for responses 😀

 

[megajocke]

positive and negative rectifier + center tapped transformer = short circuit... Draw it up and you see that the diodes short the transformer during one of the half cycles. If you have a centertapped transformer, connect the center tap to the common after the rectifiers instead.

The picture Brian posted will work, connect it like that if that is the board you have.