(Tittle change) No sound when I lift my JMPS NBF wire?

[john l]

Hey guys, heres the deal. My old style impedience selector went out on me a while back so now I have seperate 4 and 8 ohm jacks in its place. Id like to try a version of the resonance mod where you just solder in a .0033uf cap in serries with the purple feed back wire but when I tried t it I got no output fearing I was going to burn something up I put it back the way it was untill I figure this out. What am I missing here?

Heres how the jacks are wired. Im green compared to most here guys so if you see any mistakes dont keep it to yourselves lol.
Thanks very much for any help.

[IMG:431:767]http://img.photobucket.com/albums/v299/ ... 413584.jpg[/img]

[M Fowler]

I installed this resonance pot in my HRP build works great.

[john l]

I installed this resonance pot in my HRP build works great.

Right theres nothing to it which is why Im a little confused as to why it wouldnt work. You can see the feed back wire going to the speaker tap the cap would simply go inbtween the two connections right? I dont get it

[M Fowler]

I hope colossal doesn't mind me posting this .pdf but this shows how I wired mine.

[john l]

So yeah somethings up, I tried lifting the NBF wire again last night and I get no output but I do if I clip it to the 4 or 8 ohm taps Im good. From the little Ive been able to dig up my color coding should be

Grey-16ohm
Green-8ohm
yellow-4ohm
Orange-common

At this point my two big questions are.
Can anyone corfirm my color coding?
"If" this is correct. Is my wiring at the jacks correct?

[Reeltarded]

Colors are right. So my head hurts. Orange to tip, tap to sleeve with NFB. Err backwards rather.. I told you my head hurts.

[john l]

Colors are right. So my head hurts. Orange to tip, tap to sleeve with NFB. Err backwards rather.. I told you my head hurts.

LOL, what? So your saying it looks right to you then

Heres the whole board if it helps some how.

[IMG:431:767]http://img.photobucket.com/albums/v299/ ... 124139.jpg[/img]

[Firestorm]

The only way I can think of that lifting the NFB wire would shut down the output is if the PI has lost its ground connection through the presence pot. The PI then pulls its ground through the feedback resistor and the speaker. (Not great for the speaker in the long run since that puts a small but steady DC voltage across the voice coil.) Measure resistance to the chassis ground from any lug on the presence pot and check to see if the ground connection is open. Can't think of anything else that would do what you describe.

[john l]

The only way I can think of that lifting the NFB wire would shut down the output is if the PI has lost its ground connection through the presence pot. The PI then pulls its ground through the feedback resistor and the speaker. (Not great for the speaker in the long run since that puts a small but steady DC voltage across the voice coil.) Measure resistance to the chassis ground from any lug on the presence pot and check to see if the ground connection is open. Can't think of anything else that would do what you describe.

Thanks so much for the help man! Okay disclaimer time as I said Im green compared to most of you so please bare with me

The amp is open and bled down in front of me
I read 100k from all the lugs on the presence pot to the chassis. I then set my meter for continuety and am getting a steady beep from the back of the pot to the chassis. Ill get pics up but one thing I notice is that the ground bus going accross the pots doesnt terminate anywhere on the chassis it just uses the pots. Is this correct?

[Reeltarded]

That is correct. The pots carry the bus, and they self-ground to the chassis.

[vibratoking]

I then set my meter for continuety and am getting a steady beep ...

Just a suggestion. Don't rely on the beep that the meter puts out to verify that you have continuity. Set it to measure resistance and read the result. That beep may not mean what you think it does.

[Firestorm]

I read 100k from all the lugs on the presence pot to the chassis. I then set my meter for continuety and am getting a steady beep from the back of the pot to the chassis.

That's likely the problem then. 100K is your feedback resistor. Depending on which model it is, one leg of the pot should be grounded to the pot housing, or connected to ground through a separate 4K7 resistor. Either way, you shouldn't read more than about 5K from any leg to ground.

[Reeltarded]

Pres pot! Back of pot. Left leg (up orientation) is ground, center is cap, cap to ground (back of pot) right leg purple wire to 100k nfb resistor on board.

I see you have a white wire coming out of the -side of the board for the presence, but I see your presence wire disappears in an odd way up the board, and it looks like someone used shielded wire on the pot to wherever it terminates now. Where does that wire terminate?

That .68 on the pres pot is supposed to be center lug and grounded to the back of that pot.

[john l]

I then set my meter for continuety and am getting a steady beep ...

Just a suggestion. Don't rely on the beep that the meter puts out to verify that you have continuity. Set it to measure resistance and read the result. That beep may not mean what you think it does.

It jumped around a little but when I managed to hold my trembling hands still enough (lol jk...kinda) they ranged from .3 to .7 on the resistance setting

[john l]

Pres pot! Back of pot. Left leg (up orientation) is ground, center is cap, cap to ground (back of pot) right leg purple wire to 100k nfb resistor on board.

I see you have a white wire coming out of the -side of the board for the presence, but I see your presence wire disappears in an odd way up the board, and it looks like someone used shielded wire on the pot to wherever it terminates now. Where does that wire terminate?

That .68 on the pres pot is supposed to be center lug and grounded to the back of that pot.

Sorry I dont know how to multiquote yet.
FWIW and an effort to save face lol... Im not the guy that did these modifications, with the exception of the PPIMV and tying the grids on the VI this is how I got the amp.

The sheided wire is only grounded on the back of the pot the sheilding is clipped back for a quiet run Id imagine. The center conductor wire comes up top side in line with the NFB resistor.

As far as the pot wiring would this account for whats going on? Im waiting for close ups of the pres pot to upload and Ill post them.