Feeler: an "Eee-Zzz" christmas present...ez1073 and ez1073-500

[DT_Music]

So I finally "finished" my first build (if you buy anything from mouser DON'T do economy shipping) but every time I plug it in I fry the fuse.
For reference I've built 6 of the 500 series EZ1073 pres, I've done 2 U87 clones, 5 DIYRE colour pres, a couple guitar amps, several pedals and I'm a full time luthier so while it's possible I have some bad solder joints, I do have a bit of experience with that part and everything looks good.

However this is such a big build with so many small parts it's totally possible that I put something in backwards, missed some connection somewhere or just plain misunderstood an direction. After my first power on attempt for instance I realized that I had misread the colourbook and paired the blue and grey wires and the brown and violet wires from the transformer. Hopefully that alone didn't fry it, but if it did I'd rather know that right out the gate.
Any insight or advice on where to start troubleshooting would be greatly appreciated.

 

[innercityman]

So I finally "finished" my first build (if you buy anything from mouser DON'T do economy shipping) but every time I plug it in I fry the fuse.
For reference I've built 6 of the 500 series EZ1073 pres, I've done 2 U87 clones, 5 DIYRE colour pres, a couple guitar amps, several pedals and I'm a full time luthier so while it's possible I have some bad solder joints, I do have a bit of experience with that part and everything looks good.

However this is such a big build with so many small parts it's totally possible that I put something in backwards, missed some connection somewhere or just plain misunderstood an direction. After my first power on attempt for instance I realized that I had misread the colourbook and paired the blue and grey wires and the brown and violet wires from the transformer. Hopefully that alone didn't fry it, but if it did I'd rather know that right out the gate.
Any insight or advice on where to start troubleshooting would be greatly appreciated.

That's been a long time I've built it but I remember frying fuse at first attempt to fire it up. The reason was simple... I've put a normal fuse and this unit requires a "slow blow" fuse. Is it what you put inside ?

 

[DT_Music]

That's been a long time I've built it but I remember frying fuse at first attempt to fire it up. The reason was simple... I've put a normal fuse and this unit requires a "slow blow" fuse. Is it what you put inside ?

Thanks for the response! I was using fuses I bought off amazon that were described as "slow melt" but just in case I've ordered new fuses from digi-key. I would love if that's all it is!

EDIT: @innercityman New fuses arrived and everything is working as it should! I've got signal, EQ is working and it's super quiet! Thanks so much for your help!

 

[TillM]

I've a question regarding the biasing process.
The preamp has sound and no hum or noises, the only thing is, that when I crank it totally up, then I get a motorboat effect.
So when I push the preamp to 65db and turn the trim fully clockwise, I get a motorboat effect and when I turn the trim down, it sounds like a telephone.
When the trim is totally turned down, then the effect is gone.
Where I've to look ?
The bias process I made with my DMM and a sine generator.

UPDATE: found the mistake. I had it used for calibration in my Fredenstein Bento lunchbox. With my IGS Panzer there is no problem.

 

[innercityman]

Thanks for the response! I was using fuses I bought off amazon that were described as "slow melt" but just in case I've ordered new fuses from digi-key. I would love if that's all it is!

EDIT: @innercityman New fuses arrived and everything is working as it should! I've got signal, EQ is working and it's super quiet! Thanks so much for your help!

You're welcome. Happy that I could help and your unit working as it should and giving you satisfaction.

 

[EarthTone]

Just finished up building two more of these bad boys last night! The 500 series. I now have a total of 8 channels of this gorgeous Neve sound in my rig; 4 x 19” rack mount versions with EQ and 4x 500 series preamp-only versions. They all work and sound beautifully. They are my preamp of choice for most applications. Especially good is recording synths through the Radial Jensen transformer coupled DI’s. Or my sax with a u47 into them. Whatever you choose. It’s all gravy. Thank you Colin!

 

[DT_Music]

So my first build of the 19" unit with EQ is working great and I love it, but I was building a 2nd one at the same time and for various reasons I couldn't put the final touches on it until recently and this 2nd one keeps blowing fuses just like the first one used to, except now I definitely have legit slow blow fuses. I've tried comparing the two boards and they look damn near identical. Any thoughts?

 

[EarthTone]

So my first build of the 19" unit with EQ is working great and I love it, but I was building a 2nd one at the same time and for various reasons I couldn't put the final touches on it until recently and this 2nd one keeps blowing fuses just like the first one used to, except now I definitely have legit slow blow fuses. I've tried comparing the two boards and they look damn near identical. Any thoughts?

It’s weird it was happening to me too on one of my builds, but only during calibration. Once I went through enough fuses to get it calibrated and closed the case, it doesn’t blow fuses anymore. No idea why. It sounds identical to the others and hasn’t blown a fuse since and I have been recording & mixing with it for 6 months since completion. Does yours blow fuses even without test equipment hooked up to it?

 

[DT_Music]

It’s weird it was happening to me too on one of my builds, but only during calibration. Once I went through enough fuses to get it calibrated and closed the case, it doesn’t blow fuses anymore. No idea why. It sounds identical to the others and hasn’t blown a fuse since and I have been recording & mixing with it for 6 months since completion. Does yours blow fuses even without test equipment hooked up to it?

Well the first one kept blowing fuses immediately as far as I know until I got the proper slow blow fuses. This 2nd one seems to be the same. I haven't checked the fuse without trying to check the voltage first, but the light never turns on. Last time, the only fix needed was the right fuse, but this time I have the right fuses so I'm a bit at a loss.

 

[EarthTone]

Well the first one kept blowing fuses immediately as far as I know until I got the proper slow blow fuses. This 2nd one seems to be the same. I haven't checked the fuse without trying to check the voltage first, but the light never turns on. Last time, the only fix needed was the right fuse, but this time I have the right fuses so I'm a bit at a loss.

It also happened to me with slow blow fuses too. Until I got it calibrated, closed the case, and left it alone. Since then it sounds/works perfectly and I’ve been on the same fuse for 6 months, no problems. Maybe just try to get it calibrated and go from there? Or check your PSU and IEC wiring. If in doubt take the board out and look at your soldering. There’s a thousand joints on there. Easy to create bridges. Clean it and shine a bright light on your joints and look at it closely to make sure there are no bridges anywhere. I’ve been sobered up many times with my soldering upon closer inspection after a problem arose. I’ve also built like 10 of these same AML’s though so I’ve been there it sucks. Stay after it dude! I only ever had one that left me stumped, the rest all worked! Could be a bad component somewhere, a cold solder, or a bridge. I hope it works out man.

 

[DT_Music]

After a couple weeks off I'm back to trouble shooting the 2nd 1073. When it comes to troubleshooting I'm not the best but I've been generally trying to go through and check what things are connected to ground that maybe shouldn't be.
Since it keeps blowing on startup and I can't even check voltages, my first inclination is that it's something around the power supply itself.
I noticed that the + pin on BR1 is continuous with ground. I don't think that's right, but what I'm not sure of is how to test the part itself. I've checked my solder work so many times and I've done so much soldering over the last decade plus, that I'm leaning towards there being a bad component but I'm not experienced with testing a lot of them. Thoughts?

 

[tony hunt]

My thought is “Divide et impera” -- remove the bridge rectifier, then test the +ve rail for continuity to ground. That should tell you if you have a diect short downstream, or if the bridge rectifier is faulty.

If there is no short downstream, you can sub-in four seperate diodes if you do not have anothe BR1. Follow the schematic towards the end of build manual.

If there is a short downstream, keep on digging in until you find it. Do not rule out a solder-bridge to ground.