Neve 1290 build completed!!

[Chrome Heart]

That's true. It's actually labelled 'case' above the smiley face.

The latest version of the ACDC PCB has two holes labeled "case". Both on the smiley face short side.

 

[penguin]

thanks haima, i was thinking of a unbalanced mixer to avoid too much coloration of output trx.

 

[desol]

That's true. It's actually labelled 'case' above the smiley face.

The latest version of the ACDC PCB has two holes labeled "case". Both on the smiley face short side.

Ah.. i guess Joe added another trace or two? Great, thanks for the clarification.

 

[Chrome Heart]

Has anyone put a power indicator light on the rack unit? Any ideas where I would draw power?

 

[snipsnip]

most obvious canditate would be to take it from 24v at the 4 pin xlr and drop it down with a resistor.

 

[redmojosteve]

That's all I did. I just put a resistor in series with a green led for 24V and a red one for the 48V (to be consistent with the go-between's 48v). Not that the 48V one is needed.

 

[Chrome Heart]

Thanks for the replies.
Are you using 12v LED's?

 

[snipsnip]

no, just normal 5v ones here. Just use whatever youve got / can get and use the appropriate resistor.

 

[Chrome Heart]

cheers.

 

[Chrome Heart]

So is the "SHLD" on the LO1166 section of the PCB going to Pin 1 on output XLR?

 

[desol]

Yes.

 

[snipsnip]

or leave it disconnected.

Read the 8u neve thread... this was discussed recently.

Jake

 

[desol]

The only real problem i think is ground loops. So if you have this covered, there's no reason not to..
It's there for a reason.

 

[Chrome Heart]

I went ahead and put "SHLD" to pin 1 on the output XLR. Biasing went without a hitch and its as quiet as a mouse. Man this thing sounds awesome. Thanks to everyone for your help, I think Ill have to start another one!
Extra thanks to Martin. Nothing like it for the money.

 

[JTraverse]

Very nice, Chrome Heart.

 

[adrian]

i was very exited because today i was powering my finished 1290 for the first time… unfortunately immediately after i switched the power on … the 12R 1W resistor burned…(the one that is on the +24v….)  i tryed again by changing it but it was the same,
do you have an idea where i could search?
maybe i did something wrong but i carefully read the assembly guide and many pages on the thread..
(what i did is changing the 5K trim log by a lin because i didn't found log at my local reseller)

i took some photo of the board if it can helps :

           

 

[haima]

something is drawing a LOT of current and burning up that resistor - you might have a short somewhere or a cap around the wrong way etc

the 12R resistor only supplies power to the output stage ("BA183AM" on the schematic) so your problem almost certainly is in that area.

look for any solder bridges on the top and bottom of the board

make sure the heatsink isn't touching anything anywhere but those two bolts/spacers. make sure it's not touching either of the 2N3055 pins.

make sure your output transformer wiring is correct and isn't shorting anywhere - DC power runs though the output transformer.


** BTW: is there a reason you used the red wire for negative and the green for positive power supply connections? this is the opposite of convention - very confusing for someone who might need to service it in the future!

you DO have the power connected the right way don't you? i expect so because none of the caps look to be exploding... but you never know - that's the first thing to check - that you do have 24vDC and it's connected the right way around.

 

[adrian]

thank you for your answer!
you're right,
i checked without my output transformer and 12R didn't burn anymore...
in fact i had connected shield on pin 2 and 4 of the output transformer....

so i tried again without this connection, R12 is ok but a little noise appear.. (not from audio) but from the card or the transformer by himself... i don't know from where it comes exactly because i don't want to let the power on too much time as i don't want burn something any more....
it's a fast tic-tic-tic-tic-tic....
any idea?
should i try power on the unit more time or do you think i will burn something else!

 

[haima]

the (acoustic) sound would be coming from the output transformer - i guess the windings vibrate a little bit with very high level signal... i've heard the output signal acoustically appearing from them before.

BUT i don't know why you have this "fast tick tick tick" sound... perhaps you have some oscillation, or something is really wrong with your power supply.

have you checked your power supply without it connected to the preamp?

then try terminating the input (stick a resistor between pins 2+3 of the input XLR - 150R is ideal, but for this test really anything from 50R - 5k will probably work ok) and turn both the gain switch and fader pot at the lowest setting. then power up and  see if the tick tick tick noise is still heard...

 

[adrian]

OK, so i tried as you said,
once again you're right but the resistor doesn't changes anything...
in fact the transformer noise appear at the 2 last gain step and disappear if i turn my output trimmer down...