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

[sl4zhz]

Start by turning off gain reduction.

With the meter turned on and your DMM set to DC volts, place the common probe on the transformer CT PCB lug and the test probe on pad 18.  What is your reading here?  Now place you test probe on the gate of Q1 and what is your reading here?

Let's start by fixing the Qbias.  Them move on from there one step at a time.

Mike

Hi Mike sorry for the late reply,
Probe on CT PCB Lug and Pad 18 with DMM on DC Volts read -2.26 VDC
test probe on GATE of Q1 is -1.60 VDC (approx)

http://www.youtube.com/watch?v=LyrXJjTclbo

 

[hymentoptera]

C27=22 nF ?
R54=470 ohm?

Yes. Replaced them, even created a little PCB and slotted them in as I was afraid I was damaging them with heath (one of the 1176 was my very first projects ever).
They both check out, in both units :S

Not in the Rev A. 

C27 should be 10nF, 12nF or 15nF depending on when you bought your Mouser cart, and R54 should be 1k2

Unless there's a mod I should I know about.

edit; nm now I remember this question is for Rev D

 

[jplebre]

yes, it is. SOrry for the confusion. The reason I'm posting here is because there are reports earlier on of people experiencing this problem, but not reports of solutions or if they found the cause. On the rev.D thread there seems to be no info whatsoever. :S

I'm very confused :S

 

[curranm]

hey there! I am still having a crackle sound on my newest rev a build. there is no crackle or distortion when the compressor is switched out. I am wondering if this is a q bias issue. I had a bum meter in there (Which Mike replaced for me IMMEDIATELY for me, do you still want the old one back?) and I did the bias with that meter.

 

[jocke153]

Hello Everyone! I have a question about my Rev A build. I have finished everything, and went on to calibrate. I got as far as step 2. My unit does not seem to do any gain reduction. When i turn the front panel pot, nothing happens and meter stays at "-20". I know that signal comes in but then, nothing. Help is much appreciated. / John

 

[mrtomcat]

So I finished the input circuit wiring, brought it over to my friend to verify and test.
Everything went smoothly, I wired it correctly and all the test worked as they should which made me of course very happy since

I started stuffing the rest of the board and noticed that R11 states a 10k resistor on the PCB but the BOM (the latest on the HB site) has it listed as a 9.1k resistor, which is what I got in the mouser cart.

Am I ok with using the the 9.1K or do I need to get a 10k one instead?

Thanks

 

[Echo North]

So I finished the input circuit wiring, brought it over to my friend to verify and test.
Everything went smoothly, I wired it correctly and all the test worked as they should which made me of course very happy since

I started stuffing the rest of the board and noticed that R11 states a 10k resistor on the PCB but the BOM (the latest on the HB site) has it listed as a 9.1k resistor, which is what I got in the mouser cart.

Am I ok with using the the 9.1K or do I need to get a 10k one instead?

Thanks

Check the bottom of the MNATS.net Rev A page.  It states any silkscreen errors on the particular board releases.  I think that is one and it should be 9.1K.  Either way it's less than 10% so you're good.  There may be others so check the list.  The MNATS.net BOM is always correct.

Mike

 

[mrtomcat]

So I finished the input circuit wiring, brought it over to my friend to verify and test.
Everything went smoothly, I wired it correctly and all the test worked as they should which made me of course very happy since

I started stuffing the rest of the board and noticed that R11 states a 10k resistor on the PCB but the BOM (the latest on the HB site) has it listed as a 9.1k resistor, which is what I got in the mouser cart.

Am I ok with using the the 9.1K or do I need to get a 10k one instead?

Thanks

Check the bottom of the MNATS.net Rev A page.  It states any silkscreen errors on the particular board releases.  I think that is one and it should be 9.1K.  Either way it's less than 10% so you're good.  There may be others so check the list.  The MNATS.net BOM is always correct.

Mike

thanks Mike!

 

[jakearon]

So I am finally at the end of my build, and have just a few more steps from calibration. I had a couple questions...

I just installed the output transformer. 6 of the wires funneled to the board, the red and blue wires went to the output xlr connectors, but I am not left with 2 other cables and what looks like a ground cable. As of now, there is a orange and a yellow wire, as well as a non-shielded cable coming from the output transformer. I have no idea where these connect to. Any insight?

Thanks

 

[Majestic12]

So I am finally at the end of my build, and have just a few more steps from calibration. I had a couple questions...

I just installed the output transformer. 6 of the wires funneled to the board, the red and blue wires went to the output xlr connectors, but I am not left with 2 other cables and what looks like a ground cable. As of now, there is a orange and a yellow wire, as well as a non-shielded cable coming from the output transformer. I have no idea where these connect to. Any insight?

Thanks

Orange and yellow are conncected together (just look in the schematic, you can see that the two windings are wired in series). The ground wire from the transformer can be cut away since it has ground connection trough the bolts and the chassis. But you can also extend it with some more wire and use it for the ground connection to the pcb.

 

[jakearon]

I dont see this in the schematics... where do they get wired to?

thanks

 

[Echo North]

I dont see this in the schematics... where do they get wired to?

thanks

They are part of the secondary on the output tx.  Just cut them short and tie them together.

Mike

 

[jakearon]

that just confused me even more. solder/tie the orange and yellow together, then what?

 

[jakearon]

Can anyone help to answer this question? Just need to know where the orange and yellow cables attach to specifically. thanks

 

[Majestic12]

Can anyone help to answer this question? Just need to know where the orange and yellow cables attach to specifically. thanks

They are connected together and that's it. Just isolate the connection with some shrink tubing.

 

[Echo North]

Ya it's two windings connected in series.  The orange and yellow are in the middle, just solder them together and to nothing else. Cover the connection with heat shrink so it doesn't short to the enclosure or anything else.

http://mnats.net/1176_reva-d_hairball_wiring_meter_circuit.html

 

[jakearon]

Great, thank you!

 

[jakearon]

Is this the resistor that people are using for their VU Lamp to attach to one of the secondary terminals?

http://www.mouser.com/ProductDetail/Xicon/286-220-RC/?qs=%2fha2pyFaduhExhmV1gUonXM4UfwVnfkQvFv0q8HVfl0%3d

Thanks!

 

[Echo North]

Is this the resistor that people are using for their VU Lamp to attach to one of the secondary terminals?

http://www.mouser.com/ProductDetail/Xicon/286-220-RC/?qs=%2fha2pyFaduhExhmV1gUonXM4UfwVnfkQvFv0q8HVfl0%3d

Thanks!

Yep that's a good one.

 

[mrtomcat]

Finished stuffing the PCB, going to finish the poties tomorrow and the meter next...getting close to getting this baby running