Neve 1290 build completed!!

[echotodd]

I'm using the JLM PSU and Go Between.  They go together quick and their website and Martin's build PDF should answer most questions you'll have.  I did email Joe about how many pres these will power safely and one AC/DC with the Amveco xfrmr will power 4 1290/1073/1084s very nicely with adequate heat sinks on the regulators.  I threw mine in an external box with plenty of room and will indeed be powering 4 preamps with it, two now and two down the road. 

 

[desol]

Hi. Does anyone have any info/advice/problems, etc. using the JLM AC/DC (with 22V 2.272A transformer) and Go Between with these 1290s. I got all the parts to build 4 pairs and want to get started but don't want to start off on the wrong foot! If anyone's had problems, it would be great if you could post them, and save others some trouble! Thanks so much.

Dan P.

Make sure all your grounding and 48v circuit is hooked up good. When you put the 48v leds for the go-between through the case, make sure they don't touch the inside metal. Use the biggest heatsinks you can...i had to slightly modify mine to fit on the reg's. I didn't use the clamps. I soldered all the mic wires directly to the back of the go between pcb's.(didn't like the clamps, don't know why .....Always have the fuse hooked...etc, etc.

That's most i can think fer now. I smoked an acdc with the led and no fuse! bad smell...

 

[djn111]

I like to build a pair to, I try to send you a message informing about the pcb's but your inbox is full  .

 

[danjpiscina]

Hi. Does anyone have any info/advice/problems, etc. using the JLM AC/DC (with 22V 2.272A transformer) and Go Between with these 1290s. I got all the parts to build 4 pairs and want to get started but don't want to start off on the wrong foot! If anyone's had problems, it would be great if you could post them, and save others some trouble! Thanks so much.

Dan P.

Make sure all your grounding and 48v circuit is hooked up good. When you put the 48v leds for the go-between through the case, make sure they don't touch the inside metal. Use the biggest heatsinks you can...i had to slightly modify mine to fit on the reg's. I didn't use the clamps. I soldered all the mic wires directly to the back of the go between pcb's.(didn't like the clamps, don't know why .....Always have the fuse hooked...etc, etc.

That's most i can think fer now. I smoked an acdc with the led and no fuse! bad smell...

OK. Thanks. Also, I was reading Martin's assembly guide ("assembly.pdf") and on the PSU page he highlights that the layout is for 220V. I'm in the USA, so what should I do differently? And how do I adjust the trim pots? I realize these are silly questions, but quite clearly I'm a newbie so it's ok! Thanks.

 

[madriaanse]

OK. Thanks. Also, I was reading Martin's assembly guide ("assembly.pdf") and on the PSU page he highlights that the layout is for 220V. I'm in the USA, so what should I do differently?

Hi Dan, I'm not sure what document you're talking about? Page 7 of the assembly guide shows wiring for 120VAC: http://www.musiciansgig.com/ez1290/assembly.pdf

Wiring for countries with **220VAC** is shown here: http://www.musiciansgig.com/ez1290/220V_ACDC.pdf

And how do I adjust the trim pots? I realize these are silly questions, but quite clearly I'm a newbie so it's ok! Thanks.

The trimmers on the ACDC are adjusted by using a voltage meter, and adjusting the pots until you read the right voltages, +24VDC and +48VDC to ground (0V) in this instance. The trimmer on the EZ1290 is adjusted with a scope/signal generator as described in the assembly guide (page 6), but you can get fairly close by adjusting the trimpot until the TR3 collector voltage to ground reads 22.6VDC. (given your PSU voltage is really close to +24VDC).

Hope this helps,

M.

 

[danjpiscina]

Thanks so much Martin! This really clears things up! I'll get right on it and hopefully have a pair finished soon. I'm planning on getting one pair right before building the other three. Thanks again,

DP.

 

[danjpiscina]

Hi. Bad news for me! I finished building JLM's power supply following Martin's build notes. Double-checked everything and turned it on. SMOKE. I fried the 10 ohm resistor by the smiley face logo. After I unscrewed the board from the case, and looked under the magnifying glass I noticed there was a tiny (I mean tiny) solder bridge between that resistor and one of the 4007's. Not sure why the fuse didn't blow. Does this mean I fried a lot of components? Should I try replacing the resistor and testing again? Thanks for listening!

DP.

 

[desol]

Hi. Bad news for me! I finished building JLM's power supply following Martin's build notes. Double-checked everything and turned it on. SMOKE. I fried the 10 ohm resistor by the smiley face logo. After I unscrewed the board from the case, and looked under the magnifying glass I noticed there was a tiny (I mean tiny) solder bridge between that resistor and one of the 4007's. Not sure why the fuse didn't blow. Does this mean I fried a lot of components? Should I try replacing the resistor and testing again? Thanks for listening!

DP.

Where was the fuse and what size?

Doesn't take much to blow something up. Tiny solder bridge is more than enough. Try replacing the resistor, double/quadruple check everything, don't hook it to the 1290 boards(yet)...try again and test the trimmers to see if they work for starters. I try not to bolt anything down till i know it works...saves time in the end.

D.

 

[danjpiscina]

Thanks for the reply Desol. I actually haven't even started building the 1290's yet. Just the PSU. Gonna replace that resistor and make sure things are solder-bridge free! The fuse is placed where Martin's assembly guide puts it.

DP.

 

[desol]

Hey Dan,

Ok. From Joe at JLM:

"A lot of toroidal transformers will specify the fuse needed due to their huge power on surge. If the transformer mains fuse is high due to the surge then secondary fuses should be fitted before each AC in on the AC/DC. Again their size depends on the load on the AC/DC outputs."

Same thing that happened to you, happened to me. I had a 1.5 amp fuse on the mains and when i powered the ACDC, it smoked anyway. So, i decided to put the fuse on the secondary 0 volt(which i now know is wrong) and then the fuse worked. So i guess what we want, is multiple fuses here.

The datasheet fuse on the 120vac transformer primary, and then a 1.5 amp fuse on each AC input into the ACDC. Totalling 3 fuses.

I need to put one back on the 120v main in.  ;D

D.

 

[madriaanse]

Hi Dan,

Also, make absolutely sure that there isn't any continuity anywhere between the voltage regulators and ground/case - make sure you have all the right insulating spacers/pads etc. Familiarizing yourself with the smell of burnt resistors is a key element in learning and troubleshooting electronics.

EDIT: also, looking at the ACDC, the diode next to the 10R is used for the -V side of the ACDC - which you don't need for the EZ1290 project. So chances are if you did do any other damage it won't matter - just unsolder LM337.

Best,

M.

 

[desol]

Yes. My above experience was with my API's, so i needed +/-.

Also, I think, but don't quote me...that for proper full wave rectification, with just the positive rail at 1.5 amps...you need to make some modifications to the ACDC. Again, check with Joe.

D.

 

[madriaanse]

Also, I think, but don't quote me...that for proper full wave rectification, with just the positive rail at 1.5 amps...you need to make some modifications to the ACDC. Again, check with Joe.

That's correct. As-is the ACDC can source 1 Amp. If you double the four 1N4007 for the +-V rectifier you can get up to 1.5 amps (the LM317's max rated).

 

[danjpiscina]

DESOL AND MARTIN, YOU ROCK! thanks so much guys. this is my first (successful :-[), real electronics project (the PSU alone, next step a pair of 1290's followed by 3 other pairs!). As I'm sure you know, having something not blow up feels good!

So I took the LM337 out of the picture, replaced the 10 Ω, put the other fuses in place and powered up. NO SMOKE

I calibrated the +24 and +48 and now I'm setting it all in stone, so to speak.

Then comes the real fun part: mic pre's!

I'm sure I'll be posting a lot more to come, so I hope you guys are there to watch my back and make sure I don't burn down the apartment building!

Thanks again,

DP.

 

[danjpiscina]

P.S. : does anyone have any recommendations for a decent, low-priced oscilloscope for projects like these? There's all kinds up on ebay but I'm just not sure what I need.

P.P.S. : Anyone using the JLM Go Between (alone, no DI)? All we have to do is hook up the 48V from the AC/DC to the 48V on it? That's the only part I don't understand. I'm making 2 channel versions so just daisy chain? It seems too good to be true!

DP.

 

[Siegfried Meier]

Hey guys,

Anyone else using output faders other than the P&G RF11 and RF15?  Those pots are $125 and $240 respectively...a bit more than I'd like to spend just yet for those, but I will if it's the only good thing there is...

Thanks,
Sig

 

[3nity]

I use an 5K alpha and couldnt hear any difference with or without!!
ITs very clear... and cheap!!

 

[Bluzzi]

The NEVE drawings call for a fader. A fader is just a pot with a linear (straight) interface instead of a rotary one. They are interchangeable.....and will fit a 1RU a lot easier. ;D

Jim

 

[Siegfried Meier]

The NEVE drawings call for a fader. A fader is just a pot with a linear (straight) interface instead of a rotary one. They are interchangeable.....and will fit a 1RU a lot easier. ;D

Jim

Wow thanks for the tip (lays down sarcasm pretty thick).  Of course I wasn't actually referring to a linear fader, I was referring to a rotary fader.  I was asking what others used for a ROTARY fader.

Thanks for the info 3nity - does the 5k cut the signal completely?  Or is that what the 10k does?  I can always replace with the P&G type later on, good to know regular alphas work too for the time being.

Thanks,
Sig

 

[echotodd]

DP,

You can either daisy chain or just run another wire from your 48V output on the JLM AC/DC board.  It'll work nicely and you will be happy!

Todd


Edit for clarity.