Phoenix Gold Phorum

i recently bought an eq215x that was supposed to have a blown earth track but i can't find anything blown and it works fine (on the bench), should the outer sheild be earthed? if so mine arn't!

pics below of rca's, i'm trying to determine which is the positive and negative!

marko wrote: but i can't find anything blown and it works fine (on the bench), should the outer sheild be earthed? if so mine arn't!

You're kidding, right?

I knew I should have tried it out whilst it was here

woosey did say it worked fine in the home on a 12v converter but no good for the car, as in will pick up all sorts of noise in-car.

at this point all i can think of is a dry joint somewhere but 1st i need to suss out where the rca's ground to...

Only thing I can tell you about those eq 's is that in many cases the pins of the in- and outputs tend to get cracked loose from the board.
This can only been seen when it's fully taken apart, and with the board upside-down.
Put a big lamp on it, and watch the solder-points with a magnifying-glass.
I've re-done all those points on all my three eq's.
At my 230, I even took the whole rca's out, cleaned the pins, and re-soldered them on the board again, because a thin layer of corrosion prevented the pins to flux the solder.
Also watch for solder on BOTH sides of the board; if not, re-solder!
GOOD LUCK.
nico

Sounds like cold solder joints to me also. Try using some non corrosive solder flux < liquid type preferred> and scrub up afterwards with solvent based flux remover.

The RCAs inside that unit are common only to the internal power supply ground and not to ground for the 12 volts side. Thus the input and output RCAs should read connected on their shields but not to ground, as this would cause a ground loop for sure.

My 232's have a switch but its located in the Line driver circuit, but it works and reduces ground noise on my setup by running it floated.


Hope this helps, they are not referenced to ground to my knowledge C

how do i check them then?

read between each shield with your ohm meter. It should not read to ground of the 12 volts, and they should circuit between each other, Give it a try C

so red probe on +v and black probe on rca shield with mm set to ohms? i'll give it a shot.

marko wrote:so red probe on +v and black probe on rca shield with mm set to ohms? i'll give it a shot.

No No I meant red tip to a shield and black tip to any other shield, and any tip to true electrical ground of the 12 volts side ...Yeah thats sounds better C

with no power to the unit i'm getting 0.5ohm between rca shieds, not sure if this is right or i'm even doing it right lol!

"and any tip to true electrical ground of the 12 volts side"

will this be one of the grounds on the circuit board then? not sure what you mean by "true electrical ground"

The ground for the 12 volt feed is the true electrical ground for the device. < i.e. the case and Primary main power ground>
There should be no circuit between this and the rca shields, at least not in any of my records and such.
The entire circuit for the audio section is on the RCA shield ground only, there is NO connection to the power ground, in fact all power supply feedbacks are opto coupled for isolation from Primary power ground.

There is absolutely NO connection of the audio circuits or the secondary of the switching power supply back to the original 12 volt circuitry other than a single 2500 volt isolation opto-coupler

RCA and primary power grounds are isolated.


Does that sound better ? Its hard to describe a electronic circuit in type written words without it sounding confusing, I know

checked it and there's no resistance between rca shields and true ground, now what?

bet there's nothing wrong with it! i should try it in the car really but i'll do what i can on the bench 1st.

I would touch up the RCAs solder just for general principals and look the entire circuit board over on its back side for bad solder. the power supply has a big resistor in it i think check it for bad solder. Don't be afraid to change out the power supply caps with new ones again just for GP's.

LMK what you find my friend C