[BUILD] 1176 Rev F/G - new board, new transformer!

[dbonin]

Hey,

So I've had a pre 2016 rev f/g for years now, working great. All of a sudden, a few years ago, a 60 cycle hum appeared. The hum occurs when the unit is on with no input or output connected (using a 0db 1khz sine wave with scope and just a scope). I can also hear it when its hooked up to a signal chain.  I have been all through the unit many times and re-flowed just about everything a few times at this point, dc voltage rails are good. I can't seem to track down this hum.... Nothing appears to be cracked nor do any joints seem to have come apart. Any information regarding troubleshooting this would be a great help, thanks!

Usually bad AC power filter caps, but the unit is not that old...  still, I'd start there.

 

[Fet Sounds]

Hello evrybody,

Maybe somebody can help me a littlebit since i'm stuck already and i haven't begun yet! ;-)


I've read and searched in the forum and in this thread but i couldn't find anything.


I'm trying to source all the surface components for a new unit, specifically a Rev G, and build it using the "old style" pcb which i have. I've found the BOM and all the rest of documentation in the beginning of this thread (it's named "BOM FOR REV F/G USA"). First of all, i've found some discrepances in the BOM between the components listed and them on the real pcb. Some are missing on the pcb, some just different value, but that is not the main problem. The issue is that in the doc i have, where it says "for optional IC input" there is any component at all, so it looks like the BOM i have is not for the IC version, wich is the one i'd like to make. At the same time in the photo of the pcb built up i see the components that is missing in the BOM, exactly those which are missing in the BOM for the IC version. I'm sure i'm missing something or i am probably getting completely idiot if everybody buit the units with no issues as i see. I really can't get it.
Is the BOM just for the G revision? And so is there another one for the F..?

Sorry for those weird questions!

I did many kits before, also some FET / Rack but is my fist time with a bare bone pcb.


Thank you so much guys!

Marco

 

[EvLoutonian]

Hello evrybody,

Maybe somebody can help me a littlebit since i'm stuck already and i haven't begun yet! ;-)


I've read and searched in the forum and in this thread but i couldn't find anything.


I'm trying to source all the surface components for a new unit, specifically a Rev G, and build it using the "old style" pcb which i have. I've found the BOM and all the rest of documentation in the beginning of this thread (it's named "BOM FOR REV F/G USA"). First of all, i've found some discrepances in the BOM between the components listed and them on the real pcb. Some are missing on the pcb, some just different value, but that is not the main problem. The issue is that in the doc i have, where it says "for optional IC input" there is any component at all, so it looks like the BOM i have is not for the IC version, wich is the one i'd like to make. At the same time in the photo of the pcb built up i see the components that is missing in the BOM, exactly those which are missing in the BOM for the IC version. I'm sure i'm missing something or i am probably getting completely idiot if everybody buit the units with no issues as i see. I really can't get it.
Is the BOM just for the G revision? And so is there another one for the F..?

Sorry for those weird questions!

I did many kits before, also some FET / Rack but is my fist time with a bare bone pcb.


Thank you so much guys!

Marco

I have a couple of BOM doc's that I referred to from when I built my Rev G versions..
I'll see if i can attach here...

 

[Fet Sounds]

Hello EvLoutonian,

Thanks a lot!

I saw the two BOMs attached, it can come very handy to doublecheck for sure!

Mike also gave me the confirmation by email that is all on the BOM.

Its was confusing to me becouse where it says "For optional IC input" sometimes there is any component at all, there is just an empty line, probably becouse they used the same text layout from the other revisions. Fine, i'm new to it! I was sure it was all correct...

I've found some other tiny problems. For instance:
1) component C 22 from the BOM is missing on the real pcb.
2) component C 5 is .22 uF on BOM and 100 uF on pcb

I'm sure there is an explaination and i'm missing it! I'll go on and see what's going to happen.

Thanks for the quick replay to you and Mike!

Marco

 

[sam system-d]

Hello EvLoutonian,

Thanks a lot!

I saw the two BOMs attached, it can come very handy to doublecheck for sure!

Mike also gave me the confirmation by email that is all on the BOM.

Its was confusing to me becouse where it says "For optional IC input" sometimes there is any component at all, there is just an empty line, probably becouse they used the same text layout from the other revisions. Fine, i'm new to it! I was sure it was all correct...

I've found some other tiny problems. For instance:
1) component C 22 from the BOM is missing on the real pcb.
2) component C 5 is .22 uF on BOM and 100 uF on pcb

I'm sure there is an explaination and i'm missing it! I'll go on and see what's going to happen.

Thanks for the quick replay to you and Mike!

Marco

I think it's important to learn to read a schematic.. You'll see C22 might not be on the pcb but off board. For C5, always double check with schematic/help thread.
Also, read all you can before starting a project.
Especially this :
http://mnats.net/
I hope it clears a bit things up.

 

[Fet Sounds]

Hello,
Thanks for your answer. Absolutely usefull.

I'm not an electronic engineer, nor i studyed anything of EE unfortunately, i'm just trying to have units for myself and learn to build some useful basic projects, i absolutely dig with you about being able to read schematics and to search the more you can about what you're doing, i know is not an easy argument. Sometimes is just very difficoult to find the time to study that hard when you dedicated a lot of time to other kind of things or have to spend in the studio daily. I had come across the mnats page already and read a lot and i will read it as deep as i can. It depends on the time you have. I planned to read some manuals that some guys recommended here on the forum. The first built i did (racking some Studer channels) took alomst a year to get the mistakes and solve them, but then i've sold 5 in a week all around the world. I'm sure it will take time to get how to move in this new project. Thank you so much for the help, much, much appreciated!;-)

Cheers.
Marco

 

[ReynoldsAudio89]

Hello all, hopefully somebody can help. I finished the power supply and have an issue. Frame is grounding appropriately, I am getting .2ohm on the chassi as I should. I turned it on for the first time and the probe slipped and I believe ground hit either N or L on the IEC.(My IEC is slightly different than what is in the build guide) that pulled the breaker in my home for the room. No smoke, no theatrics. Shut everything down, and start measurements over... There is a slight dark spot on the IEC terminal in the unit but I don't know what pin it is on.... No other smoke or dark spots on the unit. When I go to measure VDC, I am way off mark. Cathode of CR8 I am getting 1.5VDC (Should be 30VDC) and cathode CR6 I am getting -1.8VDC (Should be -10VDC). Stragely, the Fuse is still in tact. Did I just cook the IEC Port? Is there anything I can do?

 

[sodastereo]

could you upload a photo?
Carefully check transformer vac BEFORE it is rectified to dc.
If you can, just measure vac, without connecting to the board

 

[ReynoldsAudio89]

could you upload a photo?
Carefully check transformer vac BEFORE it is rectified to dc.
If you can, just measure vac, without connecting to the board

Yes, what would you like a photo of? At what point/ where do I check that voltage? I can upload all the photos for some help. Thanks!

 

[sodastereo]

First of all, I use google translator, excuse me if I'm rough with words.
You must measure the transformer T3 in empty, that is to say without connecting it to the plate, use alligator clips if necessary or insulating tape to avoid electric shocks with the plate. With the multimeter measure in VAC between CT and AC, measure the 3 cables and write it in this post. should be around 25vac. if that is wrong, check if from your interlock, you should confirm that you have voltage in that transformer.
If you have it then the problem is on the main board, start by checking the diodes (cr7-cr8-cr9-cr10) if the diode bridge is ok, check lm317 and cr6. you should concentrate on having +30 -10v there.
At pin 3 of lm317 you should have 35vdc approx. and on pin 2 30vdc. corroborate it, the photos are 2, one assembly of the plate in general, and another where the spark occurred

 

[lovebuzzz2]

Hello, is there anybody who could help me to determine which revision of Hairball 1176 I actually have? I bought one pre-built Hairball 1176 years ago, without much knowing of the differences between revisions, and it was actually advertised as Revision D...

I liked the sound very much and now I would like to have another unit of the same revision. Problem is - it says 1176LN REV F/G USA on PCB, so I am completely lost which one I have now... D, F or G? :O

 

[Echo North]

That's a Rev G.

That PCB gives you the option to build a Rev F or G. The only difference between the two is the Rev F uses a UTC-O12 (C-3837-1) input transformer, and the Rev G uses an IC input instead of a transformer. You can see the IC input being used on that PCB.

Mike

 

[lovebuzzz2]

Oh, great! Thanks for a quick reply, Mike!

Does it means one can relatively easily rebuild Rev F to Rev G and vice versa?

 

[lovebuzzz2]

Well, I guess there got to be some daughter PCB where to mount C-3837-1 input transformer... Sorry for my dumb question.. is it available? I guess I can't find it on Hairball site..

 

[z11111]

Kind of silly question but I have a few UREI B11148 transformers, plus the UREI PT and enclosure from some old graph EQs with seized faders that I finally want to do something with. Anyone using the B11148 in this project? I’m sure someone has over the past 10+ years it’s been around!

 

[sam system-d]

Kind of silly question but I have a few UREI B11148 transformers, plus the UREI PT and enclosure from some old graph EQs with seized faders that I finally want to do something with. Anyone using the B11148 in this project? I’m sure someone has over the past 10+ years it’s been around!

Hairball Audio Rev F is using it I beleive (rack format).

https://groupdiy.com/threads/build-1176-rev-f-g-new-board-new-transformer.33834/
Edit :
Didn't realised it was this thread. I still have to finish my 2 rev F, but I actually have 2 b11148 that I'm gonna use on those.