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

[sailorlee15]

Hey everyone, I built up mnats rev A 1.2 board and am burning r32. I checked the wiring of the output transformer and it matches the board and the v2 pdf. I have read though the previous posts but they seem to be different circumstances. The unit passes audio. I am getting the correct 30 and - 10 volts from the PS. My readings at the output trans with r32 removed are violet- 0 grey- 0 black- 30 white/red-30 white/black-30 brown-30. im reading 30 where r32 should be. If someone could point me at a thread if this has been discussed or give me some things to try i would greatly appreciate it.thanks!

 

[ChrioN]

Look at the schematic, you will see where you should get 30v. About the burnt resistor, I think I've seen this problem talked about before.
You might want to browse through this thread and look for it.

Hey everyone, I built up mnats rev A 1.2 board and am burning r32. I checked the wiring of the output transformer and it matches the board and the v2 pdf. I have read though the previous posts but they seem to be different circumstances. The unit passes audio. I am getting the correct 30 and - 10 volts from the PS. My readings at the output trans with r32 removed are violet- 0 grey- 0 black- 30 white/red-30 white/black-30 brown-30. im reading 30 where r32 should be. If someone could point me at a thread if this has been discussed or give me some things to try i would greatly appreciate it.thanks!

 

[sailorlee15]

Thanks for the suggestions Chrion. I reread the entire thread and it seems that most of the issues of r32 burning were with the v1 boards. I am using the v1.2. pretty stumped as to where to go from here. any suggestions would be greatly appreciated

 

[marktokach]

I am trying to use grayhill rotary switches for the rev a mnats 1176. I have 2 parts i tink will fit the mnats pcb's but I'm not sure. 2 pole 6 position and 4 pole 3 position for ratio and meter.

http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=US&WT.z_homepage_link=hp_go_button&KeyWords=71A30-04-2-03N&x=13&y=21

http://search.digikey.com/scripts/DkSearch/dksus.dll?FullDetail&name=71B30-01-2-04S-ND#usewithchildren

Will they fit or does someone know which ones will?

 

[ChrioN]

There is a datasheet. Everything will be answered in it.

 

[bobine]

The Hairball BOM for Rev A has had a wrong Mouser part number for R44, the 5K trimmer resistor. 

It should be T93YA502KT20 for 5K, (not T93YA205KT20, which orders a 2M trimmer).

 

[sailorlee15]

I've been comparing the rev "a" schematic to the mnats pdf and have noticed that there is no connection to C9 from white/red on the mnats schematic. I see only white/red going to r32 to ground. On the original schematic I'm seeing an additional connection going back to to C9 in the signal line preamp.  Could anyone shed light on this? I'm searching for the reason behind why my r32 is burning up.

 

[Rob Flinn]

I've been comparing the rev "a" schematic to the mnats pdf and have noticed that there is no connection to C9 from white/red on the mnats schematic. I see only white/red going to r32 to ground. On the original schematic I'm seeing an additional connection going back to to C9 in the signal line preamp.  Could anyone shed light on this? I'm searching for the reason behind why my r32 is burning up.

If you read this thread you will find the answers.

 

[dmp]

SailorLee,
My understanding is that there are two rev A schematics, one for S/N 101-125, one for higher.
The Mnats version is for the low S/N. The wht/red of the transformer does not connect to c9 in this rev.
My guess would be to check around Q5 & Q6 - I don't think the emitter of Q6 / wht/blk should be 30v if things are set up correctly. The base of Q5 should be biased with the voltage divider at the R29/r30/r14 node, then the emitters of Q5 & Q6 should be a diode drop lower. 
If you are stuck with a problem like this, you can keep posting more info - for instance, a picture of the board and transformer. Someone might spot a problem.

 

[dmp]

Forgot about this (from mnats revA page):
"To make the 1176 limiting amplifier, however, just replace Cx6 with a wire link and leave Rx14 off the Signal Line Amp board. "

 

[Pieter001]

Im looking for the wire picture of the 1176 rev A. Back in the thread i found a picture of the Rev D wiring.
Also one of the Rev A wiring, but when i opend the link to the rev A picture i got the message: This image or video has been moved or deleted.
Does someone have the picture on his pc and want to post it?

 

[Pieter001]

Got 2 spare wires on the hairball output transformer. Where do i need to connect them to? Or not

Thanks

 

[Biasrocks]

Got 2 spare wires on the hairball output transformer. Where do i need to connect them to? Or not

Thanks

Put some heat shrink on them and tie them off.

Mark

 

[baadc0de]

Theoretically, what would happen if R4 were 270k instead of 270r... ?

 

[Pieter001]

Finnished my 1176 today. Got some problems with it. The first thing is that i dont know where to connect pad 18 from the ratio board.
The second problem is that the unit won't compress. Audio passes fine and the input and output gain works. The meter shows +8 and +4 but nog GR, Also dont hear any GR.
Maybe this has something to do with pad 18 ;D

Also like to know how i can get the 12v lamp in the VU meter working.

Thanks

 

[ChrioN]

There is no "pad 18" on the ratio switch pcb.

 

[Pieter001]

Thats weird. It isn't mentiont in the info file on hairball audio as well.
I got a black ratio pcb with the rev A kit from hairball audio. With connection nr 1 named pad 18.

Pads info of the ratio board:

1 - 18
2 - BLK
3 - 20
4 - GRN
5 - 21
6 - 15

Don't have a camera so i can't take a picture

 

[ChrioN]

Maybe you got an old one. It says "RelPot" on mine, you connect it to the counter clockwise pin on the release pot.

 

[Pieter001]

That was the one. Hear the compression now. But the meter dont show any GR.
If i switch the atack pot to OFF the signal gets realy distorted. the VU meter shows that the signal gets realy loud if i use the off switch.

I used the hairball info to wire the pushbutton pcbs and the rev D wire picture in this thread. Is there a wire problem?

Thanks for the help!

 

[ChrioN]

There is a rev A wire picture also, that one is correct. It is somewhere in this thread.