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

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tata said:
Paul, i think im looking for something similar to the 1108 Hi/Low gain option:


not sure, but i think the 1108 schemo shows the High gain (S1)?
Click to expand...

Looking at the etching file I would say yes. You could also try putting a trimmer in for the actual switch and dial the exact amount of gain you want to see if you already had a case and didn't want to drill any new holes in the face plate.

Let us know how you go.

Thanks!

Paul
 
kessconn1 said:
Didn't expect anyone to go through the whole thing just thought maybe something would jump out to someone familiar with the build . yes all transistors were replaced except for q11 and q1. judging from my voltages that are off i would assume that these are the problem but i am not skilled enough to confirm this without replacing them. Which i will do but i would like to confirm these are my problem before replacing them. to confirm q 6 is brand new and all voltages off of it seem to read correctly

Conner
Click to expand...

Q11 is not in the audio chain.  You could remove Q1 completely and see if that fixes the noise.  I would be surprised if it did, but it's worth a try.
 
Hairball Audio said:
Q11 is not in the audio chain.  You could remove Q1 completely and see if that fixes the noise.  I would be surprised if it did, but it's worth a try.
Click to expand...

Ok so removed q1, some strange stuff happens when i try to pass signal. sound is different sounds a little bit like something is oscillating, but now no signal passes whatsoever even with all ratio settings pushed in. and if I touch caps c1-3 there is a loud audible sound that I can only describe as star wars laser. and still when i put my hand close to the signal amp noise gets louder. however this time the input and output seem to have some control over the volume of the hiss. I guess my next step would be to replace q1 with a new transistor and see if anything changes. if there are any other trouble shooting steps I could take before this please let me know.

thanks you so much  for the guidance on this

Conner
 
kessconn1 said:
Ok so removed q1, some strange stuff happens when i try to pass signal. sound is different sounds a little bit like something is oscillating, but now no signal passes whatsoever even with all ratio settings pushed in. and if I touch caps c1-3 there is a loud audible sound that I can only describe as star wars laser. and still when i put my hand close to the signal amp noise gets louder. however this time the input and output seem to have some control over the volume of the hiss. I guess my next step would be to replace q1 with a new transistor and see if anything changes. if there are any other trouble shooting steps I could take before this please let me know.

thanks you so much  for the guidance on this

Conner
Click to expand...

I would not be touching things in the circuit.  If you touch it with anything, touch it with a DMM or scope...something that would give a scientific measurement. Touching the components could harm you or the component.

No adding Q1 won't fix it. Q1 is the GR element...without it your compressor is a 45dB mic pre. So if your getting no signal without Q1 adding it back won't make a difference.

Not sure at this point.

You could send it in for repair.  If you have and can use a scope trace the signal through the gain stage and see where is it goes weird.

Mike
 
Hairball Audio said:
I would not be touching things in the circuit.  If you touch it with anything, touch it with a DMM or scope...something that would give a scientific measurement. Touching the components could harm you or the component.

No adding Q1 won't fix it. Q1 is the GR element...without it your compressor is a 45dB mic pre. So if your getting no signal without Q1 adding it back won't make a difference.

Not sure at this point.

You could send it in for repair.  If you have and can use a scope trace the signal through the gain stage and see where is it goes weird.

Mike
Click to expand...

Yea, I know touching live components is a big no no.  At this point I am grasping at straws trying to figure out what the issue is, anything that can give me a lead. Sadly i do not have a scope. I might be able to borrow one however. In the meantime I am not against the idea of having someone else take a look. Should I email Hairball directly for quotes on repair or PM you? If cost is not restrictive i have no problem going that route

Conner
 
id need a little help,

i see/hear asymmetrical amplification / saturation as i turn up the input.
(GR OFF mode - same with Q1 removed)

measuring at point 15:
this is with input around 10 o'clock:
1176_00.png


and this is at 12 o'clock:
1176_01.png


seems the output of the Altran trafo is ok, so i guess this happens at the input stage.
can you please tell me where to look?

thanks
 
kessconn1 said:
Yea, I know touching live components is a big no no.  At this point I am grasping at straws trying to figure out what the issue is, anything that can give me a lead. Sadly i do not have a scope. I might be able to borrow one however. In the meantime I am not against the idea of having someone else take a look. Should I email Hairball directly for quotes on repair or PM you? If cost is not restrictive i have no problem going that route

Conner
Click to expand...

You can email us for a repair request if you want to go the route.

Mike
 
tata said:
id need a little help,

i see/hear asymmetrical amplification / saturation as i turn up the input.
(GR OFF mode - same with Q1 removed)

measuring at point 15:
this is with input around 10 o'clock:
1176_00.png


and this is at 12 o'clock:
1176_01.png


seems the output of the Altran trafo is ok, so i guess this happens at the input stage.
can you please tell me where to look?

thanks
Click to expand...

Asymmetrical clipping is normal in colorful analog gear. That's part of the color.

Mike
 
Hairball Audio said:
Asymmetrical clipping is normal in colorful analog gear. That's part of the color.

Mike
Click to expand...


thanks Mike,

but if there is something i could do to this particular circuit to make it more "ideal" (=less colorful?) i would do it. this would also help me understand how things work.

if there is a serious amount of asymmetry in a gear, the input signal polarity of an asymmetrical source can make things or break things.. right? so its good to know what polairity the gear "likes" (to eat). :)
 
tata said:
i see/hear asymmetrical amplification / saturation as i turn up the input...
can you please tell me where to look?
Click to expand...
Replace R11 with a 50k pot. Adjust for best symmetry. Remove pot and measure; select closest value.

I think Gus PMed me about this right after I finished the PCB design some time ago.
 
mnats said:
Replace R11 with a 50k pot. Adjust for best symmetry. Remove pot and measure; select closest value.

I think Gus PMed me about this right after I finished the PCB design some time ago.
Click to expand...

thank you Mako!

changed the 10k (PCB labeled) to 9k1, its better now.
 
i see R40 is 24k in the original UREI documents - from rev.A to rev.E
its (R64) changed to 2k4 in rev.F and up - all the rev.A / D clones i know use 2k4 (incl. the new FET Rack)

can you please tell what effect this has on the GR?


1176_R40.png


whats the best way to have longer travel for the Release pot. on the fast side?  simply replacing the pot with a 2M or 1M?  on the original i have a feeling that the Lin. taper is not the best on the fast side - a tiny move makes too much changes sometimes and  i dont really need the slow(est) setting.
are 1/2W pots a must for the Attack / Release?

thanks
 
Hi guys!

It's been a while since I've been there: I've built succesfully 2 of those revA and after years of good and faithfull services strange noise occurs, some kind of pulsation, oscilation I don't know... Here's a link to listen to it:

https://drive.google.com/open?id=0B0XP7Z0gIHgdUll2c0UxY1RsUUU

The periodic side makes me think that it could be a capacitor issue. And the fact that it occurs even with the GR off also makes think that it could be in the preamp/line or PSU section.
What do you think? Any idea?
Thanks for your help guys.

Best,
Ben
 
evilcat said:
Hi guys!

It's been a while since I've been there: I've built succesfully 2 of those revA and after years of good and faithfull services strange noise occurs, some kind of pulsation, oscilation I don't know... Here's a link to listen to it:

https://drive.google.com/open?id=0B0XP7Z0gIHgdUll2c0UxY1RsUUU

The periodic side makes me think that it could be a capacitor issue. And the fact that it occurs even with the GR off also makes think that it could be in the preamp/line or PSU section.
What do you think? Any idea?
Thanks for your help guys.

Best,
Ben
Click to expand...

Maybe heat related?

When it's oscillating, see if the PSU voltages for voltages around the transistors in the line amp have changed.
 
evilcat said:
Hi guys!

It's been a while since I've been there: I've built succesfully 2 of those revA and after years of good and faithfull services strange noise occurs, some kind of pulsation, oscilation I don't know... Here's a link to listen to it:

https://drive.google.com/open?id=0B0XP7Z0gIHgdUll2c0UxY1RsUUU

The periodic side makes me think that it could be a capacitor issue. And the fact that it occurs even with the GR off also makes think that it could be in the preamp/line or PSU section.
What do you think? Any idea?
Thanks for your help guys.

Best,
Ben
Click to expand...
We don't know much about the test conditions such as what, if anything is connected to it. But as suggested in the FAQ linked from the first post the best way to find the fault is to use a signal tracer. Start by shorting or putting a low resistance across the input. Trace from output back to input. When the noise disappears you now know where to look - just before it disappeared.

It's much faster than trying to guess out the entire signal chain where the problem is.
 
mnats said:
We don't know much about the test conditions such as what, if anything is connected to it. But as suggested in the FAQ linked from the first post the best way to find the fault is to use a signal tracer. Start by shorting or putting a low resistance across the input. Trace from output back to input. When the noise disappears you now know where to look - just before it disappeared.

It's much faster than trying to guess out the entire signal chain where the problem is.
Click to expand...

Compressors are connected to the output of my preamps and then to the input of the AD. Even with no signal thru the units, noise is there. I've never had to debug a unit, never use a signal tracer but I'll ;)
Thanks


Hairball Audio said:
Maybe heat related?

When it's oscillating, see if the PSU voltages for voltages around the transistors in the line amp have changed.
Click to expand...

Ok I'll try that too; thanks very much!

Ben
 
mnats said:
We don't know much about the test conditions such as what, if anything is connected to it. But as suggested in the FAQ linked from the first post the best way to find the fault is to use a signal tracer. Start by shorting or putting a low resistance across the input. Trace from output back to input. When the noise disappears you now know where to look - just before it disappeared.

It's much faster than trying to guess out the entire signal chain where the problem is.
Click to expand...

Hey Makko, (or anyone else, of course ;))

I finally got my hand on an oscilloscope. 1st time for me, I know how a scope works but I never used one for troubleshooting/repairing. I will need a little help to tell me how to operate, please. The basics of using a scope.
Another question, what do you mean by "shorting or putting a low resistance across the input"? Which value of resistance? Across which points: ground, hot, cold?
Thanks and sorry for such newbie questions...

Best,
Ben
 
Hello all,

I'm repairing a Rev A PCB version 1.2 (not the 1.2.5) for a friend and was having issues calibrating the null adjust. I figured I would see what was changed between the 1.2 and the 1.2.5 and noticed the 8.2k resistor was swapped for a 18k (R76). I swapped the original resistor out for a higher resistor and had no problem adjusting the null point after that.

Now I'm wondering was else was changed and if there's a schematic around that clearly labels the changes? Any opinions on whether it's worth swapping out the rest of the parts for better performance or sound?

Thanks so much
 
Finally got my unit going properly today, little mistake on the switch wiring and changing the wiring on the TXF now it sounds pretty impressive i must say!!
now all i want to do is mod the G1176's i have into rev D!!
 

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