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

[brewbacca]

Good news is that I was able to get the preamp sections working on both my units. I had a few bad transistors between the two units. Checking for around 600 mA between the base and the emitter is the key there.  But be really careful when you pull those things out when replacing. These boards can be pretty fragile.

Bad news is that the EQ's are not working correctly.
- On the first there is a lot of distortion and the signal is pretty low.
- One the second there is a lot of pops and static

Anybody have any thoughts about the EQ sections?

Thanks!

*Edited for grammar*

 

[haystack]

Look, I know this isn't very technical,  but the pops and static I have had when completing a project were down to
soldering errors. I too had loud pops and building of static noise in one project.  I look over the pcb and all joints under a glass and found  some joints that I hadn't soldered properly. The joints were not easy to spot but once gone over with a soldering iron/solder
the pre amp in question was sorted but it took a couple of goes.

Hope you get your ez's sorted out. Don't give up.

Haystack

 

[brewbacca]

I'll check the soldering around the eq sections again, but I've gone through the joints with a magnifying glass and checked for bad joints a few times already.

 

[Deepdark]

Hi guys

Quick one for you. Concerning the heatsink installation HS-1 and 2. Do I have to put some TO-220 insulating pad between the regulator and the heatsink? Secondly, Do I have to solder the heatsink pin on the pcb pad? Thanks folks

 

[Slenderchap]

The amount of heat it generates is minimal.... the 24v regulator heatsink only gets luke warm... and the 48v heatsink is really only there for mechanical support.

So there is no need for insulators.... soldering the heatsink pins is desireable for mechanical stability.

Colin
www.audiomaintenance.com

 

[Deepdark]

thank you colin. I'm finishing mounting it all and now, I have a question about de main switch. In the color book tt asks for a DPDT switch. Why not a DPST? I'm a little confused about which one I need (On-ON, ON-none-ON, etc. etc). ON-ON seems the simpler to find.

I linked a drawing with a configuration of DPDT and one SPST. I would like to know if I'm correct.

 

[brewbacca]

Figured out the unit with distortion.  I had a short to ground somewhere between r65, c61 and q14. I couldn't figure out what specific component was responsible and didn't see any solder bridges, but replacing them seems to have done the trick. So now the EQ is working.

Edit: Got the second unit to not make pop/static sounds by yet another touching up a couple joints connected to ground and then yet another cleaning with alcohol.

So now I'm in business.

 

[KJ]

Hi all,

I've spent hours reading the forum but I still don't quite understand what's not working with my ez1073. I read 24V between J5 and J6, as it should, but between J3 and J5 it's 45V and nothing happens when I adjust the R10. And I get 360mV at R26 and nothing happens when adjusting R20. I understand there might be a problem with the 2N3055 that the shakeproof washers causes a short, but I don't quite understand how. I tried with M3 screws and washers instead, but the problem remains. Does anyone have any idea what might be wrong?

Cheers

 

[Deepdark]

Finished building 1 EZ1073. No issues, everything run as expected. Calibration went fine, no noise, no hum, totally silent. Huge sound, fat, nice eq. Awesome job Colin. Thank you.

 

[olebrom]

Hi,

Finallly got around to build this. Had to change q4 and the 2n3055 before the unit passed any sound. Everything seems to be working so far except the mid freq pot. The following frequencies are working : Off, 360hz, 700 hz, 1600hz. The rest are not working or occasionally working. If I fiddle the pot back and forwards a few times suddenly its all ok. Fiddle back and forwards again and its not working.  When its not working I can sometimes "push" the pot and it works. I have re- soldered  all the points that corresponds to this pot so my guess is that the pot is not working correctly... ? Any tips or hints? Change the pot?

 

[andrea19837]

my MID FREQ don't work at all. all the others are perfect, and VOLTAGE is perfect, no hum no noise, the line and mic pre work like a charme, only the mid FREQ don't work at all..any advise? maybe a fault inductor, or transistor in OP AMP B? or a POTENTIOMETER faulty?

 

[andrea19837]

OK, i fix it.. now everything work 110%.

COLIN SUGGEST AND FIND THE RIGHT FAULT:

"Andrea,

I expect that the switch was rotated when you fitted the pins.

Remove both pins… put the switch in the position which it shows in the build manual… refit both pins.

Regards,
Colin Adshead"


wannabe mistake bytheway It's sound wonderfull .

thank you.

 

[leitrim_lad]

Hey there. . Just a quick one for ye. I built two of these units..  both worked first time when I plugged then in.. just one issue tho.. one unit is 4db louder than the other.. don't notice it when doing anything on solo channels but when working on stereo channels it's an issue.. just wondering would anyone have any ideas? Am I right in saying the output knob should always be up full to get same level as input or should it be half way? I seem to be able to get both units matched in level when one units output level is half way and the other is fully to the right..

Thanks

 

[haystack]

Just a quick thought-

you don't have the eq  on,  on one of the units and not on the other?

 

[saxmonster]

have you tried switching the cables going into the preamps?  maybe one of the cables is bad and if you swap them them the other channel is then louder?

 

[leitrim_lad]

Hey thanks for the replies..

No tried both units with the eq off and the eq on but everything at 0 and its the same problem..

Ive also tried changing the cables to the unit and the same issue is there.. Its not a cableing issue

Thanks

 

[haystack]

Could be worth just checking your resistor values carefully.
Hay

 

[leitrim_lad]

hey there ive checked all the resistors on both units and they all match up..

thanks

 

[leitrim_lad]

Hey there, just a quick one.. i seem to be able to make up the levels close enough by turning the line in gain down one notch on the unit thats 4db louder. Would it be possible i put the pin in the wrong place when in stalling the knob?

I was running a 1k tone through each unit and then knocking one out of phase.. Should the tone cancel itself out completely? Its dropping level but not canceling out completely.. Would this be normal?

Thanks a million

 

[leitrim_lad]

Hey there,would anyone have any ideas on what might be causing the 4db difference? thanks in advance