[BUILD] 1176LN Rev D DIY

[matta]

Hi Christoph,

Thanks very much, it was most useful and I not have a matched pair of FET's, wrote down all the measurements of the others incase I need to find similar/same one later (though out of 20 I got one pair).

Cheers

Matt

[quote author="crisotop"]

Also going to use this as a BUMP for my own questions RE FET matching for the GR section, any help would be appreciated.

Hey Matt, I used the little testrig as found in PRR's Post (in the middle of the page, 05. Jan 2005, 6:17). It's not an 'in-circuit' method, but worked perfectly on my two revision J stereo clones.

hth,
christoph[/quote]

 

[kdawg]

Hello - I have built Mnant's rev D 1176 (version 1) with a UTC o-12 input and CM-96731 output transformer. It is working, but then after a few hours R32 (39 ohm) decides to commit suicide. Its only a 1/4 watt, does it just need to be beefier or is there a bigger issue?

I wired the output transformer according to Version 1 board colors (not Version 2 like I saw someone did on another post) and its compressing and the output is good as well. Remaining leads from tranny not attached to board go to the XLR and meter input.

ALSO - I do have a bit of humm going on when I crank it enough... could this be because R32 is open? I tried moving input tranny around, no change. I do have the Cinemag screwed directly to chassis - any isolation required? Power toroid mounted on opposite side of chassis.

-kdawg

 

[Andre]

[quote author="kdawg"]Hello - I have built Mnant's rev D 1176 (version 1) with a UTC o-12 input and CM-96731 output transformer. It is working, but then after a few hours R32 (39 ohm) decides to commit suicide. Its only a 1/4 watt, does it just need to be beefier or is there a bigger issue?

I wired the output transformer according to Version 1 board colors (not Version 2 like I saw someone did on another post) and its compressing and the output is good as well. Remaining leads from tranny not attached to board go to the XLR and meter input.

ALSO - I do have a bit of humm going on when I crank it enough... could this be because R32 is open? I tried moving input tranny around, no change. I do have the Cinemag screwed directly to chassis - any isolation required? Power toroid mounted on opposite side of chassis.

-kdawg[/quote]


I won't worry about the hum until you solve the resistor problem. What voltages do you read over the resistor and in the area?

 

[crisotop]

Thanks very much, it was most useful and I not have a matched pair of FET's, wrote down all the measurements of the others incase I need to find similar/same one later (though out of 20 I got one pair).

brilliant - do you want to build a stereo-linkable version? because I still have got a matched pair flying around somewhere (I was really lucky, out of 10 I got 2 matched pairs for a dual and one single pair!)...

regards,
christoph

 

[kdawg]

I took some measurements but of I course I left them at my shop. I do remember I have 10.5 volts across R32 when it is blown. 30.5 volts on the main rail, -10 volts on the negative rail.

Seems that would be about .26 mA across R32, and about 2.8 watts... hmmm?
a bit more than a 1/4 w!

I'll get the other measurements soon, thanks.

-kdawg

 

[mitsos]

[quote author="kazper"]I paid $80 for a sifam and LED light new, bulb was way cheaper. I don't think you will get better for much less than that.[/quote]
please don't tease us... :grin: where?

 

[Chrome Heart]

Where are you guys buying pcb's for this project? I saw Hairball audio had some. Is there a preferred supplier?

 

[Echo North]

Mnats sells the boards for the revision D version. Info is located here:
http://www.groupdiy.com/index.php?topic=330976

I just sell PCB's for the pushbutton switches.

Mike

 

[Chrome Heart]

Thanks Mike.

 

[kazper]

[quote author="mitsos"][quote author="kazper"]I paid $80 for a sifam and LED light new, bulb was way cheaper. I don't think you will get better for much less than that.[/quote]
please don't tease us... :grin: where?[/quote]

http://www.meterdistributor.com/

 

[Miska]

Does anyone know if Alpha rotary switches can be programmed like Lorlins can? I can't find the info in the datasheet...

I have located a 6 position Alpha switch and I would like to use it for ratio/slam and wire it like Mnats did. It has 1 position too much though...

Or even better:
A source for 2 deck 2 pole 5 pos rotary switch in Europe? All I could find was this:
http://www.banzaieffects.com/Rotary-Switch-2-level-2x2x6-pr-20275.html

/Miska

 

[crisotop]

www.conrad.de #709387 - 62

hth, christoph

 

[Miska]

That's grand!!!!

Many thanks, Christop! The switch doesn't exist on the swedish Conrad site. That's why I couldn't find it...

/Miska

 

[kdawg]

I'm reposting the message above with voltages just so it's all together:
------
Hello - I have built Mnant's rev D 1176 (version 1) with a UTC o-12 input and CM-96731 output transformer. It is working, but then after a few hours R32 (39 ohm) decides to commit suicide. Its only a 1/4 watt, does it just need to be beefier or is there a bigger issue?

I wired the output transformer according to Version 1 board colors (not Version 2 like I saw someone did on another post) and its compressing and the output is good as well. Metering is OK too.

VOLTAGES (when r32 is gone)
30.5 volts on power rail
R26 / R34 Junction - 20.3 V
Brown TX wire - 19.5 V
Black TX Wire - 30.5 V
White/Black TX wire - 11 V
White/Red TX wire - 10V
Across R32 spot - 10 V

Is there any reason why the PCB would need isolated ground from chassis? Input transformer needs to be isolated?

-kdawg

 

[bluezplaya]

Can anyone post a diagram of how to wire the attenuator. I decided to buy one from Hairball Audio and I don't quite know how to wire it.

 

[Echo North]

Have you seen the post by Matta about 1/2 down this page?

http://www.groupdiy.com/index.php?topic=27741&postdays=0&postorder=asc&start=180

Mike

 

[bluezplaya]

:wink:

 

[bluezplaya]

Okay, so I finally got my IEC plug in the mail from Mouser and wired it up to the power transformer. My AC voltages look good from the power transformer and the 30v is good from R87 and -10v from CR6. I powered up and immediately started hearing some high pitch ringing or singing or something from the output transformer. I patched in some audio and listened through headphones to hear a signal and all I got was some seriously scratchy and poppy and distorted sounds ( and no, I wasn't listening to Nine Inch Nails).

The input seemed to be working like it should, the output knob was the culprit. It spit, popped, cussed at me in every way as I turned it. The meter was jumping somewhat; when I was able to dial in somewhat of a grainy signal, the ratio, attack and release appeared to be working, given the signal it hard to work with.

I'm using the Rev2 board, Cinemags, lorlin switches and the attenuator from Hairball Audio and wired just like the pic from Matta. I'm using shielded cable for the input stage and solid wiring for the ratio board, etc.

Do I need to look at transistors? Is this something wrong with the output stage? The Cinemag is wired correctly from the output.

Any help appreciated.
Adam

 

[bluezplaya]

I'm stranded on a DIY island for 19 days and no one has replied to my cry for help! :green:

I spent some more time today with the Rev. D to try and figure this thing out. I double checked both input and output transformers, seems good. I swapped transistors in the line amp stage and got the same results (they were fine.) Do I need to look at replacing Q1 or Q6 transistors?

When feeding a strong signal through it I still get a high pitch squeal that my dog isn't too crazy about. There's also distortion on the signal. I can hear a difference in the signal when I switch the bypass on and off and I'm pretty sure the ratio and attack and release switch and knobs seem to be changing the sound.

I notice in bypass mode the meter doesn't move (obviously), in GR mode there is no movement, and in VU mode it jumps right along with the signal. Is there something wrong with my meter, or does this not have any affect on the problem?

HEEEEELPPP! I'M STRANDED!!!!!

 

[nielsk]

My first units is up and running, sounds good, compressing fine, but there is no meter tracking adjustment. Meter works correctly for input and output, I can confirm 10 dB of compression with the compresor "in" and no compression with it out, but in GR meter mode there is no change over the full swing of the tracking adjusment trimpot. Everything else adjusts correctly. I see around 1-1/2 dB of deflection on the meter in GR mode, and if I crank up the input it goes down, but there is no way to get it match the actual amount of compression. I confirmed the trimpot, the jumper, the meter.... ANY ideas?
BTW I am using 2n5088s for Q12 & 13