[BUILD] 1176 Rev A - Back to the beginning...

[mnats]

I have 2 rev a ver 1.1 boards that came with 4 boards each. Looks like there are 2 power supply boards that needed to be snapped off the main board as well as the other 2. I see on mnats site that there is a ver 1 and ver 1.2 patrs list. Not sure which to use because mine says ver 1.1. My main questions are; can I use just one of the power supply boards, that are different from the new double sided one, to power a dual 1176 rev a, or do i need to get the new one, and what version of parts list do I use? TIA, Mark.

The psu board reads; PSU Mnats 26.01.09

The single sided power supply boards are larger but use exactly the same components so either will easily power a dual unit with an adequate transformer.

The newer BOM should get you closer to the first 24 units made, but be sure you refer to the 1176 Plosives thread if you want to build the later unit which requires some modifications along with different/added values to the ratio switches. Refer the Rev A threads and the original schematic(s) and build to taste.

 

[portix]

The value of the pots don't seems clear to me, especialy for the output. (100k/250k ?)

 

[marktokach]

Thanks Mnats

 

[gurkan75]

..not that I´ve built one, but I think the output is 250k audio taper.

 

[portix]

Thanks gurkan75

 

[StudioSQ]

so i just got my first of two worked out and...

I had the same problem lots of people seemed to be having with the meter and gain reduction acting funny. I socketed the transistors not associated with the audio path I found that the BC 107 is super stable in the meter and gain reduction circuit. It is pin compatible with the 2n5088 and all 15 I ordered worked in the meter circuit.  After it was calibrated i could swap out any of the bc 107s and it was still pretty close to on. I am just finishing my second unit with the bc107 in the gain reduction and meter area. I am expecting good things. 

 

[portix]

Hi,

I've just finish the wiring of my rev A. Everything seems to be correct.
When I powered it, the R32 (39 ohm) burn. I 've measure 11V on the resistor. Is it correct?

Any idea?

Regards,

Marc

 

[Hank Dussen]

You're wiring the output transformer wrong. If you're using the EA 5002 I think it should be brown, black/white, red/white, black, grey, purple. Starting from the corner.

 

[portix]

It's exactely the way it was wired.  :-\
Here is a picture:

 

[0dbfs]

Rev 1 & 2 boards have the OT wired in a different order. Proper order is silkscreend on the board. Compar schematics to board traces if it's in question.

If you hav a rev1 board and wire the OT according to the rev2 doc R32 will burn up.

Hope that helps.

Best,
Jonathan

 

[portix]

Maybe I'm too stupid, but I can't found any wiring diagram for the version 1.2, and I can't dissolder the terminal to see what's written on the board.
Is there an URL where I can find it?

Thx.

 

[Echo North]

http://mnats.net/files/DIY_1176_REVA_V1.pdf

I thought all Rev A boards had the same output wiring?

It's the Rev D that had a change between versions.

The schematic is the definitive word:
http://www.waltzingbear.com/Schematics/Urei.html

Mike

 

[portix]

Thanks. My wiring of the OT is correct. The problem is somewhere else.
I continue the investigations.

 

[Stagefright13]

I REALLY think you have a problem with the output transformer. I would fire up the board with it disconnected. Or maybe there is a short in the terminal strip? But I think your problem is right there. Of course I can't be positive but this same problem has come up a few times. Maybe solder has flowed between 2 points on the strip on the upper side of the board. I would check there first.

Hope ya get it figured out. It's a great compressor. Best of luck!

 

[StudioSQ]

where do i get the 12v for the meter on this thing, should i just use a 7812 off of the 30v?

 

[StudioSQ]

Also just finished the second unit with the BC107s, works great, even the meter.

 

[Stagefright13]

StudioSQ use this http://www.groupdiy.com/index.php?topic=275.0

John

 

[baadc0de]

Could someone who has built a revA please help me through via a messenger program or the like? I'm really a newb to debugging and I have a what I think is a strange problem... The G of Q2 shows a nice sine 1.2Vpp, D of Q2 something like 1.2V DC. I have no idea on how to debug this further. This is a new J309 in there..

More broad info: This unit won't pass signal, even with the GR circuit disabled (p22 to ground). There have been suggestions about doing the q-bias adjustment first, but this is not possible without getting a reading on the VU (i.e. the unit passing signal).

Thanks,
b.

 

[Echo North]

Lab member Gswan has a great page about his rev J build.

On it, there is a page which traces the signal through the unit:
http://www.axtsystems.com/index.php?option=com_content&view=article&id=57:1176lnproblems&catid=34:1176ln&Itemid=62

Obviously there are some differences between the A and J, however with a little reading and a DMM you should be able to trace an AC signal and see where she dies.

Mike

 

[baadc0de]

The signal on D of Q2 is a nice sine (what I put in), but the base of Q3 shows 1.1V DC with a hint of a sine there. Any ideas? There is no signal on pad 15.