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

[rainton]

send Mike at hairballaudio an email and I'm sure he will
send you a replacement VU meter if the one you have is defective...

 

[Echo North]

Ya he will!  ;D

I think I have an email from you.  I'll get caught up on my email tonight and get it sorted for you.

Mike

 

[ilikethesun]

yes that's my friend who is registred on your website He's my neighbor...

do you need I send you back the defective Vu meter ?

thanks

 

[Echo North]

Check your Pad 21 DC voltages at each ratio, you should see pad 21 yielding around  -5.5VDC at 20, -3VDC at 12, -2.2VDC at 8, -1.2VDC at 4.

 

[ilikethesun]

Check your Pad 21 DC voltages at each ratio, you should see pad 21 yielding around  -5.5VDC at 20, -3VDC at 12, -2.2VDC at 8, -1.2VDC at 4.

Hi
I dont know if you're talking to me ....

@20 : 5,81VDC
@12 : -3,14VDC
@8 : -2,31VDC
@4 : -1,48VDC

I'm waiting for the new Vu Meter to calibrate...
If I read this http://www.soundskulptor.com/fr/calc_fr.html#dbu  I understand I should see 1,09 V between pin 2 & 3 of intput XLR right to send 1khz at 0 dBu ?

 

[jakearon]

Hey all,

Im making good progress on my build! However, I am rather confused about R71 (the 2k trim pot). Bare with me, again, I am a newbie. I just bought the hairball build kit 2 months ago, so its rather new, and Im not exactly sure whether I solder a 2k cap onto the board in R71, or mount the wires for the trim pot? Can anyone help? Also, i dont think I got a trim pot in my kit, but I do see places for it to mount on the front panel. If anyone can shine a light on this, this would be great. Sorry for the newbie questions. I read a bunch on this in previous posts and it just confused me more.

Also, if I just get the trim pot and mount it with wire to the board in R71, thats what I Use to calibrate it, correct?

Thanks

 

[Echo North]

Hey all,

Im making good progress on my build! However, I am rather confused about R71 (the 2k trim pot). Bare with me, again, I am a newbie. I just bought the hairball build kit 2 months ago, so its rather new, and Im not exactly sure whether I solder a 2k cap onto the board in R71, or mount the wires for the trim pot? Can anyone help? Also, i dont think I got a trim pot in my kit, but I do see places for it to mount on the front panel. If anyone can shine a light on this, this would be great. Sorry for the newbie questions. I read a bunch on this in previous posts and it just confused me more.

Also, if I just get the trim pot and mount it with wire to the board in R71, thats what I Use to calibrate it, correct?

Thanks

Have you read all of this?

http://hairballaudio.com/shop/fetguide.php

All of this is addressed.

 

[jakearon]

i did indeed, but im confused at this point. can someone tell me if I should just purchase a trim pot, and from where, and if i mount wires from there to the board, or just use another 2k cap. thanks

 

[hymentoptera]

i did indeed, but im confused at this point. can someone tell me if I should just purchase a trim pot, and from where, and if i mount wires from there to the board, or just use another 2k cap. thanks

did you buy the Mouser cart? if you bought the Mouser cart and Hairball kit you should have 5 pots, not including the trim pots. input, output, attack, release and zero adjust. The zero adjust should be the Honeywell with the screw driver slot shaft, mouser part # 785-53C22K

edit:
installation instructions are here (step 6 on the hairball site), at the bottom http://mnats.net/1176_reva-d_hairball_wiring_output_zero_pots.html

 

[jakearon]

Okay I thikn I understand now. Thought they would have come from Hairball. So Ill solder the zero adjust pot right to the board like the picture at the bottom. Correct?

It was just a bit confusing because a lot of the photos had a 2k capacitor in that place instead.

 

[hymentoptera]

Okay I thikn I understand now. Thought they would have come from Hairball. So Ill solder the zero adjust pot right to the board like the picture at the bottom. Correct?

It was just a bit confusing because a lot of the photos had a 2k capacitor in that place instead.

As I understand it there shouldn't ever be a capacitor there. Do you mean trim pot? Some people opt to place a 2 kilo ohm trimmer potentiometer there instead of the panel mount one, but then you cant zero the meter later without removing the 1176 from the rack and opening the top. The panel mount pot is just a convenience should the meter drift due to heat, etc, you can zero it back out again while in GR mode. The trim pot or panel mount pot perform the same function, but the original unit had the panel mount, so it's more authentic if you can stick a screwdriver into the little hole and adjust it.

 

[jakearon]

Sorry thats what I meant. ALso, one more question. Im about to go to radioshack to pick up a fuse. Do you which one I need. I guess im going with a value of 120... (sorry im such a newbie)!

 

[hymentoptera]

Sorry thats what I meant. ALso, one more question. Im about to go to radioshack to pick up a fuse. Do you which one I need. I guess im going with a value of 120... (sorry im such a newbie)!

If you bought the Mouser cart for Rev A, it should have come with a Qualtek AC power receptacle (mouser part # 562-719W-00/02) which fits the Hairball enclosures and takes a 5 mm x 20 mm fuse and a space for a spare. The cart should also include a 5 pack of Shurter fuses that fit (mouser part # 693-0034.3111) which are rated at 250V 250mA, and are supposed to be "slow blow", but for some reason seem to blow easily. Start with these Shurters, and if they keep blowing on powerup, try to bump up to 325mA.

If you really feel like a newbie, it might not be a bad idea to read all 5 pdf sections of instructions on the Hairball site, the 6th section which links to mnats's wiring pages, watch the mnats calibration videos, and this thread in it's entirety. The vast majority of newb questions, including everything you're asking, can be found in these thorough resources, plus you get to read about some of the issues that might arise. I have my entire kit, but I haven't start building yet because I'm still researching stuff here

 

[jakearon]

Thanks for the response. Im getting close to finishing. I have a couple questions that have been brought up in this thread, but I havnt seen any definitive answers.

1. For the attack potentiometer... what is the value of the capacitor. Is it .012uf or can .01 be used?

2. Is the resistor that goes on the release potentiometer R56 or R57 on the BOM? What is the value? 5M or 270K?

3. The attack for the release potentiometer is R54 with a 1.2k resistor correct?

4. Which is the correct molex strip for the ratio and meter pcbs? Can any give me a part number. I am having trouble locating it.

Thats all for now. Thank you kindly

 

[hymentoptera]

1. For the attack potentiometer... what is the value of the capacitor. Is it .012uf or can .01 be used?

I asked this a few pages back. The original revision had a 10nF, but the closest WIMA is 12nF, so the Mouser cart includes a 12nF WIMA. It seems either will work, and besides, a 20% tolerance 10nF could in theory be as high as 12nF. I never got a good answer, but I was curious what the difference would be, and I assume that 10nF would give a slightly faster attack time. I had opted to go with a 10nF Sprague lemon drop here, as most of my film capacitors I've chosen are lemon drops. The short answer is either will work, but I'm still curious what difference it will make, and if it's even measurable.

2. Is the resistor that goes on the release potentiometer R56 or R57 on the BOM? What is the value? 5M or 270K?

According to the schematic "1176REVA_125.pdf" R56 is the pot itself, 5M linear taper and comes with the Hairball kit, while R57 is the 270k resistor that gets strapped across the CCW and wiper lugs of R56. The Mouser cart gives you a metal film, but I'm going with a old NOS carbon comp 270k at R57 for authenticity.

3. The attack for the release potentiometer is R54 with a 1.2k resistor correct?

If you mean the resistor for the attack pot, then yes, that's the one. The attack pot is R55, and it gets a capacitor (C27, 12nF) and a resistor (R54, 1k2) across two of it's solder lugs, the CCW and wiper lugs.

4. Which is the correct molex strip for the ratio and meter pcbs? Can any give me a part number. I am having trouble locating it.

I found an eBay dealer in Romania that's selling one that works. They look identical to the ones in the mnats guide. The seller's name is gorvell1984 but I don't know if they still have them, as it's been a few months since I got them. If you've never messed with molex connectors, they are a B***h to crimp unless you have the correct tool (I use needle nose pliars and take my time), so you might be better off just soldering your wires directly to the ratio/meter boards. Just my opinion, that last part.

 

[Echo North]

4. Which is the correct molex strip for the ratio and meter pcbs? Can any give me a part number. I am having trouble locating it.

The are KK .1 pitch.  Mouser sells them but I don't recommend them.  Direct solder is far more secure.

 

[jakearon]

That all makes sense. What part number were the lemon drop caps you used? You like them more than the Wima?

 

[hymentoptera]

That all makes sense. What part number were the lemon drop caps you used? You like them more than the Wima?

The WIMA is probably a much higher quality cap. The technology has likely come a long way as far as manufacturing and quality control, if you're not sure, just stick with what's in the Mouser cart.

"Lemon Drop" is a not too commonly used name to describe the style of film capacitors used in many positions in the original units. The original had these yellow cylindrical caps, either polyethylene or mylar, not sure, but they appear to be made by Cornell Dublier. There's also one or two 150nF "tropical fish" in there if I understand. Also two or three silver mica where the Mouser cart gives you ceramics. You can see all of this in photos of the guts of the originals, and I'm not aware of anyone building a revision A using the correct capacitors. I just figured I'd swap out for some of the old parts. Since these are no longer manufactured I've had to source them from various online retailers that specialize in vintage components.

There's a thread here on groupdiy where a guy in Germany posted several nice pictures of the guts of a unit with a serial number in the 140's, which would be a revision A, and between those photos and some schematics I was able to determine what positions used which parts. I just searched around for similar parts, bought many of each (sometimes dozens of each) and have been painstakingly measuring and organizing them as they come in, and pairing up carbon comp resistors, and lemon drop and mica caps, into the tightest pairs which are closest to the nominal values, for the pair of Rev As I'm building this summer.

So far I've spent hundreds of US$ on vintage parts and I still don't have everything I need, but it's been fun, and I've learned a lot in the process.

In other words, just use what's in the Mouser cart. Your unit will probably sound better than mine.

 

[jakearon]

So this is the part your suggesting right?

http://www.mouser.com/ProductDetail/WIMA/FKP4O121004C00JSSD/?qs=sGAEpiMZZMv1cc3ydrPrF2Av7JKdyW4DXN9b2ekadZs%3d

Wima

 

[hymentoptera]

So this is the part your suggesting right?

http://www.mouser.com/ProductDetail/WIMA/FKP4O121004C00JSSD/?qs=sGAEpiMZZMv1cc3ydrPrF2Av7JKdyW4DXN9b2ekadZs%3d

Wima

oh, I forgot, the .012uF is out of stock and has been replaced by a .015uF WIMA as of a few weeks ago, (mouser part # 505-MKP20.015/100/5), sorry about that. If you have the current Mouser cart order then the .015uF (15nF) MKP2 is the one.

No I haven't personally recommend that part. I was under the impression the correct value wasn't available, that's why we went with the .012uF and then more recently a .015uF

That one you linked to would work I think, not sure if it's matters that it's an FKP4, maybe someone else can comment on the difference? I know some styles of construction and types of dialectic are more desirable for certain tasks, but I don't understand all of this really.

Can anyone comment on the 10nF WIMA jakearon linked to? Is this suitable in the C27 position??