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

[TwentyTrees]

Hi Pete,

That sounds frustrating! The ez1073 is definitely a snug fit even with a custom case so I can well imagine that a little tolerance slip would cause issues.

I would definitely not support the PCB just from the front panel pots & switches - even if you've not got the mains transformer mounted on-board, the audio transformers and inductors make it very heavy for a PCB so I'd expect the risk of damage would be high. Without knowing more about the 3U case you're considering I can't really suggest anything other than "long standoffs?", but even so with all that iron the ez1073 is going to be sensitive to things like other power transformers so you might not get optimal performance if you co-house it, even if you do solve the mounting issue.

Obvious question, but have you contacted Dan about sending out a replacement case / panel?

Andy

 

[Potato Cakes]

I've used Dan's case for an ez1073 and it is snug but should fit fine. One thing to keep in mind is that I had to use the standard hex nuts on the inside for the Grayhill switches as they aren't flush with the Omeg pots when you bolt them in, causing the PCB to warp if you just tighten down the nuts as is. I also only used standoffs for the rear of the PCB as that is where most of the weight is going to be. 1/4" or 6mm will fit.

Thanks!

Paul

 

[PeteC]

Thanks for the thoughts guys.

I measured and test fitted everything again tonight and sadly there is no way the pcb is gonna fit without TX bolts and the output TX itself fouling/shorting the bottom of the case - it must be poor tolerances in the case machining.
The only solution appears to be to file out the faceplate mount holes so that the faceplate and pcb sit a couple of mm higher than they do at the moment - this might give me the clearance away from the bottom plate of the case that I need. I an do this by filing out the holes to lower them o the faceplate and thus raise the faceplate relative to the rest of the case.  Bit of a bind though to be honest. Shame after getting it running with no electronic bugs.    Not sure if Dan would send me a replacement over this side of the pond - I'll ask the question at least.
Cheers
Pete

 

[dandeurloo]

Hey Peter, I just responded to your email as well.  But I thought it would be good to have the info in this thread again.  I am pretty sure it has been covered a few times here but these threads do get long, so it is good to have the info come up again.

The design of the AML ez1073 is a little different then most.  The front of the PCB has to sit lower then the back of the PCB.  There are a few reasons for this.  The height of a 1U case, the center placement of the Greyhill switches  and pots and the size of the output transformer (which just barely fits in a 1U) are all part of the issue.  Is your issue that the front of the PCB has to tip down compared to the back of the PCB?  If so, that is normal. 

The other issue you may be running into is if you fully installed your switches and pots to the PCB prior to lining them up to the front panel.  The panels always line up if the switches are fastened to the panels first, then the PCB is fitted to the switches.  Then you solder the switches to the PCB in place so they don’t move.  This makes for perfect alignment of the switches to the front panel.  This is a common method for projects with a lot of PCB mount switches. 

With all the PCB mounted switches and pots in the front and the angle of the PCB you don’t have use any standoffs toward the front of the PCB.  The switches are more then enough to secure the PCB in the front.  In fact, the couple that I built I only added 2 or 3 standoff's toward the back of the PCB.  The output transformer also helps to hold the PCB in place(up and down) so not much is really needed.  Just a few standoff's to help things from shifting around.

For extra comfort, I trimmed the solder pins of the switches and pots pretty close to the bottom of the PCB and then used electrical tape or vinyl tape under them and between the bottom of the enclosure.  Just to have a extra layer of protection from  any of the switches shorting out on the case.  It isn’t needed but I did do it just to be extra safe. 

Let me know if this addresses the issue or if you have any more questions.

BTW, I just looked at my old emails back and forth with Colin when he supplied me all the layout info.  This project started back in 2010.  Pretty amazing! 

Hi everyone.  Tonight I just completed my 1u ez1073 build and calibrated.  Everything works perfectly first time - so really pleased with that.  However when I come to fit the pcb  into the collective cases 1u rack I find that there is no way it's going to fit without the bolts on the underside of the pcb fouling the bottom plate of the case.  When I look even closer I find that the front panel mounting holes
Look to be drilled too far down the faceplate.  There simply won't be any space to use standoffs etc under the pcb.  This is very disappointing as I waited a long time for U.K. Customs to clear my order from Dan.  I think it's just a duff case where the tolerances weren't being met by Dans supplier and its slipped through QA.    So now my only option seems to be to jointly house the 1073 inside a 3 unit rack case I have spare and have it housed with some other preamps and my headphone amp.  My question is really this - will the pcb be ok self supporting from all the pots and switches on the faceplate and if not then what can people suggest I do to support it if it's housed with other stuff inside a larger rack case?  Bit frustrated as I want to track either the ez1073 as soon as possible having heard what it can do tonight.  All ideas greatly welcomed    Cheers Pete

 

[PeteC]

Hi Dan,

Thanks for the tips - you are right in thinking that I soldered in my switches to the pcb without the faceplate - so that could be the source of some of my issues.  Too difficult to re-do that now without a very good desoldering tool.

I guess with standoffs at the rear then its just the fact that there is less than  1mm or so clearance between pins and the bottom panel at the front  - but I will look to use a sheet of tough plastic to insulate everything.  I think at the rear of the pcb everything will be fine.  The mounting bolts for the output TX are probably a little tool long for the case height- but I can replace them with something a little shorter

I'll try everything you have suggested and see if I can get it to fit without any shorts.

The things sounds bloody amazing tracking DI'd Bass through the mic channel in conj with a Bo Hansen DI box  !

Cheers
Pete

 

[PeteC]

Just to add....
I will be using a 1mm rubber sheet on the inside base of the case just to be really sure everything is fully insulated from shorting out - especially where the switches and pots are.

one quick unrelated question - whats the correct orientation for the LED - positive leg into the right hand hole I am guessing looking at the pcb traces ?

Cheers
Pete
 

 

[dandeurloo]

Hi Dan,

Thanks for the tips - you are right in thinking that I soldered in my switches to the pcb without the faceplate - so that could be the source of some of my issues.  Too difficult to re-do that now without a very good desoldering tool.

I guess with standoffs at the rear then its just the fact that there is less than  1mm or so clearance between pins and the bottom panel at the front  - but I will look to use a sheet of tough plastic to insulate everything.  I think at the rear of the pcb everything will be fine.  The mounting bolts for the output TX are probably a little tool long for the case height- but I can replace them with something a little shorter

I'll try everything you have suggested and see if I can get it to fit without any shorts.

The things sounds bloody amazing tracking DI'd Bass through the mic channel in conj with a Bo Hansen DI box  !

Cheers
Pete

If one of the switches looks to be more off then another you can use QucikChip.  That stuff works like magic in situations like this.

I use it a lot for SMD part removals. 

Talk to you soon.

 

[PeteC]

cheers Dan, and Colin,

all racked up tonight and sounding mighty fine !!

Think I might need more 1073s........ 8)

Rgds
Pete

 

[miscend]

I am struggling. The bias adjuster trimmer has no effect on DC voltage.  What are the necessary steps to troubleshooting the reason for this?

 

[Potato Cakes]

Which voltage are you trying to adjust with the bias trimmer?

Thanks!

Paul

 

[miscend]

Which voltage are you trying to adjust with the bias trimmer?

Thanks!

Paul

Hi

I'm making the new 500 series build with just the pre. In the build document it says I should be getting DC voltage of 40-50 mV from the multimeter on theTP1 and TP2 test points. However I am only getting 26.8mV.

Theres 5k Bourns trimmer for adjusting the bias. The doc says I should turn that clockwise until the DC voltage measures 90mV from those same test points. However that has no effect.

I've checked the polarity of all the caps. And I've reflowed and resoldered some of the joints. At the moment I'm trying to isolate where on the board the issue will be. I'm a beginner level builder but I've built kits from JLM and Soundskulptor.

 

[IMUTHANT]

Similar issues here. I just finished building 4 kits of the EZ1073pre, and I tried to calibrate them just now.

2 of the modules started between 40-50 mV at the bias test points, and the trimmer took that up to 90 mV, as the colourbook described. However, one has plenty of clean output, whereas the other has hardly any output, even when the output fader is way up there. Also sounded a bit highpassed possibly.

The other 2 modules are, just like the previous post, stuck in the mid to high 20s in mV, and no amount of turning the trimmer changes that.

Any input would be hugely appreciated. I've built several VP28s, JLM LA500s, hairball kits, and others. I also took over a week of slowly building these ez1073 modules, triple-checking every step and soldering well. 2 of the modules are for my buddy's professional studio, so I'm a bit bummed that I'm having these issues.

 

[IMUTHANT]

Update: Colin suggested that the 2 modules not taking as much voltage would result from either an issue with the output stage PCB or the surge control PCB because "the 20mV suggests that the
output amp is not operating." I removed both of these boards, doubled checked all the components, and reflowed all the joints, even though they all looked good. Unfortunately, I still have the same issue...stuck around 26 or 27 mV. Any ideas how else I could trouble shoot this part of the circuit? Thanks!

 

[miscend]

Update: Colin suggested that the 2 modules not taking as much voltage would result from either an issue with the output stage PCB or the surge control PCB because "the 20mV suggests that the
output amp is not operating." I removed both of these boards, doubled checked all the components, and reflowed all the joints, even though they all looked good. Unfortunately, I still have the same issue...stuck around 26 or 27 mV. Any ideas how else I could trouble shoot this part of the circuit? Thanks!

Okay I have followed exactly as you did above with limited success. Until I removed the connector on the output transformer and soldered  the wires directly to the board. I am now getting the correct 90 mV, when I adjust the trimmer.

But I now have a new  problem. I get no sound output at all when the front switch is set to 1200 ohms.  And I get a noisy output with hum when I set it to 300 ohms.

Any advice on how to proceed will be greatly appreciated.

 

[IMUTHANT]

Okay I have followed exactly as you did above with limited success. Until I removed the connector on the output transformer and soldered  the wires directly to the board. I am now getting the correct 90 mV, when I adjust the trimmer.

But I now have a new  problem. I get no sound output at all when the front switch is set to 1200 ohms.  And I get a noisy output with hum when I set it to 300 ohms.

Any advice on how to proceed will be greatly appreciated.

Thanks! That fixed everything...what a relief. Makes sense now that the molex connection would be the issue. Everything else in the kit and build was perfect, except for the molex connector. The pictures from the colour book had the molex looking different (short legs where the pictures shows long legs, and long on the short side). I just heated up the legs and pushed them through so that they looked like the diagram in the colourbook. To fix it, instead of wiring it in directly, I just pushed the legs through an extra couple centimeters and reconnected the transformers, and that fixed the issues I had in each of the 4 modules (the working one had developed the same issues eventually)

I also learned that there are two types of loctite thread sealant  : the type I had lying around is apparently the stronger type, so after a few stripped screws (and one where the nut broke loose from the rear panel and started floating freely in the panel) I eventually managed to remove the transformers in order to troubleshoot.

My buddy just messaged me that the pres sounded great in his session yesterday.

Wish I could help with those issues you are having, but I wouldn't know where to start...

 

[Slenderchap]

I can now appreciate that is not a very clear drawing... I will correct the colourbooks.

Colin
www.audiomaintenance.com

 

[IMUTHANT]

I can now appreciate that is not a very clear drawing... I will correct the colourbooks.

Colin
www.audiomaintenance.com

Didn't mean to be rude. The kit and instructions were very clear, and lots of fun. I'm just a bit inexperienced with solid molex connections.
Thanks!

 

[bluespills]

I just finished a pair of ez1073s,

One is working good, but there is a level drop when i flip the phase switch...?

The second one I have a very low output from the mic channel, and a lot of buzzing when i touch the mic gain knob... 

I have already gone over looking for bad joints and trying to clean up but no luck so far.

Any tips are appreciated!  :

 

[leadpoisoning]

I just finished a pair of ez1073s,

One is working good, but there is a level drop when i flip the phase switch...?

The second one I have a very low output from the mic channel, and a lot of buzzing when i touch the mic gain knob... 

I have already gone over looking for bad joints and trying to clean up but no luck so far.

Any tips are appreciated!  :

possible you stressed the gain pot when fitting the board and pots through the front panel openings? maybe cracked a solder joint? check around the pot for continuity maybe ...?  might be my first guess.

maybe something similar going on with the phase switch? it would be an easy fix were that the case anyway

 

[EarthTone]

Dear Everyone,

Hi! I am probably going to order 2 of these this weekend. The 1U rack version. They look & sound incredible from what I have gathered.

Just a quick question to those who have built one: I am a newcomer to DIY, but I have built 2 microphones and heavily modded 2 other microphones successfully. I repair small instrument parts for a living (sax mouthpieces, to be specific), so problem solving, following detailed instructions, and working with small parts doesn't bother me.

Based on that, do you guys think I could build a couple of these 1U rack version 1073 preamps succesffully? So far I'm very keen on DIY and I need two more preamps to fill out the last remaining spaces in my 16 channel analog i/o recording setup. Would love to make them a pair of these. I am choosing these over the SCA N72's and Sound Skulptor MP73's because of AML's reputation for having gotten this preamp right!

I read the whole build manual and nothing looks too outlandishly hard to understand.

Finally, other than the faceplate & case & knobs, is there anything else one must buy/order to finish one of these fine AML kits?

Cheers, and thank you for your patience!

EarthTone.