8 Channel, 3U NEVE 1073 completed

[Chrome Heart]

Has anyone put a power indicator lamp on the front panel? I would guess you just take the supply from the +24?

 

[sr1200]

I added that to mine, I also added VU meters, but the lamp was rated 120vac so i just tapped it off the mains.

 

[Chrome Heart]

Finished my second pair of these. I have one more pair to finish and Ill have 6 channels. These are great pre's. Thanks Martin.
This pair ended up biasing at 23.03V. There is no substitute for a scope for this procedure. 22.6V is definitely "ballpark".

 

[Chrome Heart]

Inside

 

[madriaanse]

There is no substitute for a scope for this procedure. 22.6V is definitely "ballpark".

Very true. Definitely use a scope if you can. 22.6V is more of a "field solution"

Nice looking pre there Bob!

New boards will be here today for those who missed out on the last batch.

Best,

M.

 

[dandeurloo]

Every time I have used a scope I have noticed that the symmetry changes with gain.  What is the idea position to test this in general.  Is it max gain or middle settings?

 

[madriaanse]

Set it at max gain (75dB)

M.

 

[Chrome Heart]

I set it to max gain and adjust the sine wave volume to work with the scope.

 

[MicDaddy]

FWIW I biased 8x channels using only DMM to 22.6V 

After several weeks/months(?) of use, many of the channels did not care for this and cooked the 47r next to the 5k trimmer.  Back some pages I posted pictures of the cooked 1watters.  Note some of the pres still continued to 'work' (just fine to my ears, maybe some distortions but it sounds "rock n roll") with the cooked resistors, but one would cut in and out as noted by alexidoia on the previous page.

Definitely try to use a scope.

 

[dude24man]

just completed 2 ez1290 channels, one working fab! other one,  no sound untill I hit about 50 db which is all bad distortion. I removed, double and triple checked all resistor values around gain switch. all checked out fine.  removed and double checked all caps all good! again, I have one working channel no problems!  any ideas would be helpfull

 

[Chrome Heart]

just completed 2 ez1290 channels, one working fab! other one,  no sound untill I hit about 50 db which is all bad distortion. I removed, double and triple checked all resistor values around gain switch. all checked out fine.  removed and double checked all caps all good! again, I have one working channel no problems!  any ideas would be helpfull

I would check resistor values on the entire board. It doesnt have to be just around the gain switch to present a problem in the gain circuit. Since you have a working board it should be easy to do a side by side check.

 

[dude24man]

thanks chrome, I'll go check resistor values o the rest of the board.

 

[dude24man]

did a voltage check. the middle amp voltages are way off

TR4 C-6.8  B-0.1  E-0.8
TR5 C-6.1  B-6.8  E-6.1
TR6 C-21.3 B-6.1  E-5.5

the other amp voltages seems fine

TR4 C-3.9 B-2.4 E-1.9
TR5 C-12.8 B-3.9 E-3.2
TR6 C-21.3 B-12.7 E-12.1

 

[Chrome Heart]

That sure looks like a component error to me. I would go over that board with a fine tooth comb. It shouldnt be that difficult, there are not many parts on that PCB.

 

[leitrim_lad]

Hey there, i posted some comment back on page 68 about a ez1290 i bought second hand and iv been having big problems with it. Channel 2 seems to be working perfect but channel 1 seems to have earth problems. Iv been trying to redo the earth wiring but im only an amateur to the whole DIY game and iv been struggling. How exactly do you ground these correctly. I have pictures on page 68 of how they were grounded when i got them and it definitely doesnt seem right. Any help would be great. iv read the assembly guide but still a little confused about how to ground correctly. Thanks a million

 

[Chrome Heart]

Hey there, i posted some comment back on page 68 about a ez1290 i bought second hand and iv been having big problems with it. Channel 2 seems to be working perfect but channel 1 seems to have earth problems. Iv been trying to redo the earth wiring but im only an amateur to the whole DIY game and iv been struggling. How exactly do you ground these correctly. I have pictures on page 68 of how they were grounded when i got them and it definitely doesnt seem right. Any help would be great. iv read the assembly guide but still a little confused about how to ground correctly. Thanks a million

If channel 1 is grounded the same as channel 2, I would suspect the problem is somewhere else. I think as in dudeman24's situation the key here is to closely examine all the components on the board. You have a working channel, just A/B the two and look for something simple. Generally, Ive found the problem is an overlooked component or solder joint.

 

[dude24man]

I've checked the resistors, all check out ok! I'm wondering if I got a bad cap or transistor some were.  all voltages on TR1,2 check out ok aswell.  I'll go do some more testing. thanks again chrome

 

[dude24man]

68k resistor replaced in amp with bad voltages! funny thing is when I took out the faulty resistor, it tested ok. I replaced it. working now and all voltages check out.  now to put them in a case!!!!!! thanks chrome!

 

[Chrome Heart]

Im glad you found it.
Strange that it tested good when you pulled it though.  ???

 

[dude24man]

I know, I started testing it against the working channel, I tested the 68k resistor in the circut. on the working channel it tested about 18 ohms ( not the right way to do it) the none working channel tested about 5 ohms. I pulled it out of the circut and it read 68k ohms. I replaced it and it works, go figure. maybe the resistor under a load malfuctined? arty