Neve 1290 build completed!!

[mitsos]

I have board v2.0 and it has three 1W resistors marked on the board: the 47R under TR3, and a 270R and 12R next to the +24V pad.  This is what is marked on the board, but I believe you guys may have newer boards, so.... don't know.

 

[gerardmanvuca]

yeah i got 2.1 version pcb and it has the same resistors you just mentioned. no 10R tho?!

 

[onlymeeee]

I'm not familiar with the ez1290 board, BUT on 1290 circuits, signal ground is usually tied to chassis through a 10R resistor.  I'd guess this is what the 1W 10R is for.

 

[mitsos]

Was just checking Martin's schematic and that's where it's at.  Anyone grounding their circuits this way? 

 

[snipsnip]

Im doing it without a resistor. Works fine.

 

[stitch-o]

Im doing it without a resistor. Works fine.

Those board grounding and xfmr check tips might have fixed my issues: fired up for an hour and a half and no crackle so far.
I have a session this afternoon so we'll see if these pres make the distance without breakup.

You ever get your preamps biased? I will crank the gain on the EZ1290s to full, then turn sine tone up from zero til it clips on the scope.
I need to adjust the parameters on the scope as well.

Curious as to why, Mitsos, you would use a direct box in reverse?
Wouldn't a regular connection to a DI, from line level PTs outputs, provide the mic level signal the EZ1290s wanna see?

Cheers and Thanks again!

 

[mitsos]

um, yeah, don't know what I was thinking when I wrote that...  : 

 

[snipsnip]

Im doing it without a resistor. Works fine.

Those board grounding and xfmr check tips might have fixed my issues: fired up for an hour and a half and no crackle so far.
I have a session this afternoon so we'll see if these pres make the distance without breakup.

You ever get your preamps biased? I will crank the gain on the EZ1290s to full, then turn sine tone up from zero til it clips on the scope.
I need to adjust the parameters on the scope as well.

Hi Stich, glad you have resolved your issues... lets hope they are fixed for good!

I never managed to bias my pre's.... I did as mitsos and you are suugesting (pre @ max, sine just loud enough to clip), but still dont register any change in the waveform when adjusting the trimpot. Dont know what else to try really.....

 

[stitch-o]

Maybe try adjusting the horizontal parameters on the scope so you can see a full wave.
That looks a little tight to tell, to me.

Also, maybe try gaining up the tone a little bit more to make the clipping more pronounced...
until both sides are almost clipping (unevenly), then back it off a touch. That should make the
trim adjustments more noticeable.

I haven't even done mine biasing yet, just thinkin' off the top'o'me head...

 

[snipsnip]

Stich-o - you the man!

As far as I can tell, this has worked.

Thanks  a lot!
Jake

 

[stitch-o]

Cheers!
If it worked, then sweeeeeeet!

I had my mysterious crackle come back about an hour into the session.
I pulled the top case off the power supply and it went away...even now, crackle is gone.
So, that means I need to cut ventilation in the PS enclosure I guess?
Would the PS running hot create crackles and pops? I have smallish heat sinks on the regulators...

 

[mitsos]

If your regulators ran too hot, they'd probably shut down.  At least they're supposed to.  Are you using decent 105C caps with high enough voltage ratings?

 

[snipsnip]

hmmm... my crackle also pops up now and again, but disappears when i move the cable on my transformers a bit.

I would be surprised if we had the same problem with 2 different causes.

 

[mitsos]

which cable?

 

[snipsnip]

the input or output on the tranny.

My suspicion is that the crackle is the cable joint moving under tension.

 

[stitch-o]

If your regulators ran too hot, they'd probably shut down.

That's what I thought, but its still on and still crackle free (crossing-fingers/knock on wood now) with the PS enclosure lid open.
Tomorrow is a whole another story tho.

So Snip, you got yer suckers all biased properly?

 

[mitsos]

the input or output on the tranny.

My suspicion is that the crackle is the cable joint moving under tension.

Now that I think about it, I had a problem with a bad cable... Can't remember what it was..it's bee a while. But it didn't work right!  ;D
Can you tell if it's maybe shorting either the hot or cold to the shield?

Hey stitch, how many channels do you have running and what PSU?

 

[stitch-o]

little 2 channel, 1U rack with JLM ACDC PS in external enclosure.
I just cut vocals yesterday and they sound really good!

I'll post some pics in a hot minute....


Update: The crackle returned yesterday! Damn I was pissed.
Looked under the hood today and noticed that the 4pin XLR to the PS was wired pins: 1-48v 2-24v 3-0v 4-unconnected.
As per Martin's instructions I wired the 0v to pin 4 on the PS and left pin 3 disconnected and the rack. I also resoldered the high side connections at the input and output connections.

So far, no crackle... (knockin on wood)....

 

[audiovisceral]

That sucks man. Must be frustrating. Don't you after some point just want to throw the whole thing out or start back from scratch?

After a while who knows what might be causing it. I might be inclined to just desolder it, throw out the cheap parts and redo it fresh.

Though, I see it's working now, so I guess no need.

 

[3nity]

Guys did you followed the voltages chart?
My problems were a bit the same but the Cinemag transformer was miswired.
Hope it helps