All things G1176 - the new "repost" thread.

[MartyMart]

R48 is 3.9m
R82 is 9.9k
R81 is 2.06k
R83 is 3.88k

I used 3.9m for R48
R82 10k
R81 2k2
R83 3k9
Seems close enough and no issues here.
MM.

 

[a2d]

ok also when power the unit up, in GR switch in, the meter stays at -20,
I'll  give the zero adjust pot a little turn and it jumps to +3, so I changed the trim pot and still the same thing happens, Also the meter swings from -20 to + 3 every now and again

I remember reading something about the power transformer from HB

 

[Chrome Heart]

If the transformer primaries are incorrect, you would probably smell it. However, you dont want to wire according to the sticker on the transformer, you want to use the data sheet. Apparantly, the sticker is incorrect on many, if not all of these units.
Here is a link to the data sheet.
http://www.avellindberg.com/pdf/avel_y23_range.pdf

 

[a2d]

ohhhh thats not good, I wired it to the sticker in the transformer  now that you mention it it did smell a little weird when I first powered it up

 

[a2d]

so I have blue and violet together to 120V+ and grey and brn to 120v common is this right it must be I have correct voltages

 

[Chrome Heart]

Mine is wired as per the data sheet. Blue/Violet to 115v and Grey/Brown to 0. You should also check the voltages on the PCB and make sure the +30 and -10 are correct. ( if thats what you meant) In fact, as mnats suggests, this is something that should happen once the power supply section is stuffed and before the rest of the components go in.

 

[a2d]

yes my voltages on the board are good, -9.75V and +29.3V I have my transformer wired the same as you so all is good there.

 

[gswan]

R48 is 3.9m
R82 is 9.9k
R81 is 2.06k
R83 is 3.88k

ass for pad 7 the stereo interconnect, with the release pot full CW i have -1.83V and when I turn the pot fully CCW I have -7.23 V

Point (7) is the FET gate voltage. If you have any stereo interconnect devices attached to it, remove them for this test.

1. Is your release pot 5Meg (measure it as well as check the markings)?
2. How does the attack pot position affect this?
3. Are your diodes (FDH333) in the correct way around?
4. Are your resistor values correct on the ratio switch (A pole)?
5. What happens at point (18) when you adjust the release pot?

 

[living sounds]

Hi,

got a big hum problem with my 1176 I cannot get rid of. Even with the input and output turned all the way down there is a residual hum at -60 db wired balanced with input/output transformer or at -66 db running it unbalanced. It's a dual unit, the problem is the same on both channels (both have their own power transformer). Other than that the unit is very quiet, even with the input and output cranked all the way up the noise is still below the hum. Everything else works. Lifting the ground on the output had no effect. I had the traces cut a long time ago, but this doesn't seem to be the ground loop problem anyway, as the noise doesn't go away with the output turned down.
The hum has a very broadband spectrum with many of the harmonics being as loud as the basic 50 Hz tone.


Any help would be great!
Gregor

 

[gswan]

Hi,

got a big hum problem with my 1176 I cannot get rid of. Even with the input and output turned all the way down there is a residual hum at -60 db wired balanced with input/output transformer or at -66 db running it unbalanced. It's a dual unit, the problem is the same on both channels (both have their own power transformer). Other than that the unit is very quiet, even with the input and output cranked all the way up the noise is still below the hum. Everything else works. Lifting the ground on the output had no effect. I had the traces cut a long time ago, but this doesn't seem to be the ground loop problem anyway, as the noise doesn't go away with the output turned down.
The hum has a very broadband spectrum with many of the harmonics being as loud as the basic 50 Hz tone.


Any help would be great!
Gregor

If you are sure it is not a grounding problem then check your power supply. You may have excessive ripple on the rails, which could be due to faulty caps.

 

[living sounds]

If you are sure it is not a grounding problem then check your power supply. You may have excessive ripple on the rails, which could be due to faulty caps.

No, I'm not sure it's not a grounding problem. Faulty caps maybe, the orientation is all right, I've checked.

But the voltages on the op amp look odd:

1    - 9,5
2    -0,5
3    -0,5
4    -9,67
8    0
7    16,44
6    2,38
5    -9,5


The values on the second unit are quite similar. Only -9.5V at the -Rails is way too low, isn't it? Could a faulty Zener D10 be the culprit (on both units, of course)?

 

[casrec]

Only -9.5V at the -Rails is way too low, isn't it? Could a faulty Zener D10 be the culprit (on both units, of course)?

This is very normal and even the manual states +- .5v is within tolerance for both -10v and 30v.

 

[gswan]

If you are sure it is not a grounding problem then check your power supply. You may have excessive ripple on the rails, which could be due to faulty caps.

No, I'm not sure it's not a grounding problem. Faulty caps maybe, the orientation is all right, I've checked.

But the voltages on the op amp look odd:

1    - 9,5
2    -0,5
3    -0,5
4    -9,67
8     0
7    16,44
6    2,38
5    -9,5


The values on the second unit are quite similar. Only -9.5V at the -Rails is way too low, isn't it? Could a faulty Zener D10 be the culprit (on both units, of course)?

I assume this is the GR metering op amp.
Why do you think that these values look odd?
-9.5V is OK for the -10V rail. Does it look OK on the scope?

 

[Pine]

Hi all.

Finally finished my stereo 2-1176. This is two compressors 1176LN.
My right channel working good and have problem with left channel.
Calibration is OK.
In left channel , When I move CCW Release my meter in position GR  move down. Diode FD333 on katode is +1,5V when release move CW on katode is -1,5V.

this is difference beetwen left and right channel. 
In right channel on katode (diode FD333) is -1,5V  :    -1,3V

This is my problem :

http://www.sendspace.pl/file/e1f1e428f037c53d1e07881

Klik ( POBIERZ )= DOWNLOAD

Best regards.
sosnowski

 

[living sounds]

Haven't got a scope. But I thought that the +/- voltage rails should be in the same terretory. The +-rail is much higher.

Any idea what else could it be? The odd thing to me seems to be that the hum is not affected by the output volume setting.

I assume this is the GR metering op amp.
Why do you think that these values look odd?
-9.5V is OK for the -10V rail. Does it look OK on the scope?

 

[gswan]

The odd thing to me seems to be that the hum is not affected by the output volume setting.

Then the hum is obviously introduced into the circuit after the output volume control, either in the output amplifier or as a ground loop at the output socket into the next piece of equipment.

 

[living sounds]

Then the hum is obviously introduced into the circuit after the output volume control, either in the output amplifier or as a ground loop at the output socket into the next piece of equipment.

Since it doesn't matter for the hum if the connection is fully balanced or not at all, is it safe to assume that the output sockets are not the problem? Lifting the ground there didn't make any difference either. Could a faulty part in the output amplifier (on both channels obviously) be to blame?

 

[living sounds]

I've done some more tests. It seems to be hum induced from the power transformers or even the low voltage AC lines. To solve this once and for all I think I'm going to build an external PSU. There is a link to dual 1176 PSU schematics in the META, but it's no longer working. Where can I get it? Also, would a single 25V 30 VA Xformer (center-tapped and wired in parallel) suffice to power both units (meters, but no lamps or relays)? Would connecting them to the same PSU in parallel cause any problems?

Thanks!

 

[gswan]

I've done some more tests. It seems to be hum induced from the power transformers or even the low voltage AC lines. To solve this once and for all I think I'm going to build an external PSU. There is a link to dual 1176 PSU schematics in the META, but it's no longer working. Where can I get it? Also, would a single 25V 30 VA Xformer (center-tapped and wired in parallel) suffice to power both units (meters, but no lamps or relays)? Would connecting them to the same PSU in parallel cause any problems?

Thanks!

Mako has a PSU, so do I and others. Here are some links:

http://www.geocities.com/m_natsume/psu.html
http://www.axtsystems.com/index.php?option=com_content&view=category&id=35&Itemid=64
http://www.jlmaudio.com/JLM%20Power%20Supply.htm

A single 25-0-25 30VA transformer is ideal to power two 1176 modules, including lamps and relays.

 

[Echo North]

OK I have the Avel Lindberg torroid from HB and the sticker on the side says Blue/Grey to 115v, but the data sheet at Avel says Blue/Violet for 115v. Can someone clear this? Am I missing something?

I had this same problem with this torroidal. It has to be a misprint. Wire in parallel as per the data sheet. Blue/violet and grey/brown. If you wire the other way around it will get very hot and I am sure will pop if left to long which I did not wait to see. They are great heavy duty transformers, but they should really look into this misprint on the unit itself.

Brandon  

My new batch from Avril Avel has the correct sticker on the side (same as Data).

Previous purchasers should check their PT's before wiring if they have an Avril Avel (from me or Avril Avel).

Thanks for the catch guys!

Mike

Edit: Can't spell...