All things G1176 - the new "repost" thread.

[Spencerleehorton]

Seems I had a bad solder joint on either the ratio pcb or the meter selector as compression and meter working now! When going through the setup when adjusting the attack control I don't get and difference between it being off and all the way on?
Also with release CW fully I get distortion, if I wind it back a little distortion stops?
This unit was the first unit I built and I do need to clean up the wiring and pcbs, so going to clean up first, then if have the same problems I need to go through with scope to find our where clipping is taking place.
When scope on output very clipped waveform.

Spence.

 

[Spencerleehorton]

right, i have had a bit of a look at it and it seems i was taking the gnd connection from the 0v CT of the AC!!!! oops, have now corrected this and i'm noise free!! clean as a whistle.
the distortion is still there when using fast release and input at about half? when switching to GR and +4.
Waveform looks much better than it did but still distortion?
it seem when adjusting the Q bias CCW is loudest signal and CW signal goes really quiet, i will check the solder joints around this area.
also looking at the IC's i think as they are quite old and i think they may have had some abuse!!
Ive never been happy with this compressor and always used the CLX160's i've made, now i've started looking at it and giving it attention it seem there is hope and this compressor should be very handy once i get it going properly!!
i am thinking about building a blue stripe as this seems much cleaner and simpler but i want to get this one going first.

Spence.

 

[Spencerleehorton]

one of the main things i notice when setting up the compressor is no matter where i adjust the trimmers q bias etc, i cant get the attack control to move very far? almost like the attack isn't really working?

Ah i've just checked some posts and i need to revise my method for setup as when it talks about attack CCW it means attack should be off, so click the rotary meter switch to GR off, if i've got that right?
also talks about on the video earthing the pad 22 out, still don't think this will fix my distortion when its compressing though!

Spence.

 

[Spencerleehorton]

Have gone through this a few times now and i'm getting distortion after R34, before R34 it is fine?
I've checked the main voltages and its fairly close all over.
When doing the setup i can't get the attack control to drop 10db when engaged?
can anybody help please!!!!

regards

Spence.

 

[Spencerleehorton]

Well it seems all 3 of my units don't have signal to TL 071? And the attack control doesn't drop -10db?
Any help out there?

Ive been reliably informed that there shouldnt be any signal in the TL071 so i'll stop looking!!

Regards

Spence.

 

[Spencerleehorton]

well it seems that the distortion on the output was the two 4.3R resistors, they must have been damaged when a previous Q8 or Q9 blew i reckon. Ive put in a couple of 10R at the moment and they seem to work fine.

One down two more to go!!! sounds amazing now with the OEP txf on output!!!! whoda thought!!

Spence.

 

[Spencerleehorton]

Hi,

I cant seem to get any signal showing on the VU on +4 but i get signal on the output?
Could this be a TL071 fault or somewhere else?

Spence.

 

[gyraf]

If GR shows, and VU not, chances are that you have a DC-reading meter, not a VU. At least that has been the reason in 95% or more of the related cases earlier in this thread..

Jakob E.

 

[Spencerleehorton]

Do you mean to that the VU meter has stopped working? As it did work perfectly on both channels?
I'm thinking its a wiring mistake as I've just changed it from line bal chip to transformers.
I will check all solder joints but seems really strange both VU meters don't work on +4 but work fine on GR?

Regards

Spence.

 

[Spencerleehorton]

if the VU Meter was broken then it wouldn't work at all i would have thought? it works on GR but not on GR off or +4.
any suggestions welcome. also both channels seem to be doing the same thing, that why i suspect i've either blown something or a wiring mistake!!! as they both worked fine before when i had the line balancer in it.

regards

Spence.

 

[mihailojocic]

Hello everyone!

At this moment I am at the end of making 4 G1176 boards. Very happy!!!  I had some problems but I solved it. One thing bothering me at this moment and I don't know where to search.

One of 4 boards have louder output, sorry, WAY TO LOUD! I don't even have a need for headphones amp, I can plug my HP directly on G1176 output and it is still LOUD!

I try both inputs, same situation.

Someone have idea where is the problem? Please help!!!

 

[miszt]

Do you mean to that the VU meter has stopped working? As it did work perfectly on both channels?
I'm thinking its a wiring mistake as I've just changed it from line bal chip to transformers.
I will check all solder joints but seems really strange both VU meters don't work on +4 but work fine on GR?

Regards

Spence.

what Jakob meant, was that you may have a DC meter, not a VU meter (AC) (ie the wrong type of meter installed)

i'm not offering any advice as to whether that is the case or not btw, i'm just clearing up what was said as you seem to have misunderstood Jakob's reply

 

[Spencerleehorton]

Hi,

thanks for that but the VU meter worked fine before, so its definitely the right meter, and as i said before the GR meter position works fine, just nothing on the meter when switched to +4?
Ive traced sign wave and there is a sine wave right to the meter but the meter just dont show it on +4 mode?

regards

spence.

 

[mihailojocic]

what Jakob meant, was that you may have a DC meter, not a VU meter (AC) (ie the wrong type of meter installed)

I think that all VU meters work on DC.

 

[gyraf]

Yes, but not all DC meters work as VU.

Traditionally, the "GR-shows-but-VU-not" error means that you have a DC reading meter with a VU scale glued on (for external rectifier etc.).

Jakob E.

 

[Spencerleehorton]

Hi,

I can see i wasn't clear, i am using rectifiers with these VU meters.

http://www.ebay.co.uk/itm/DC-AC-6-12V-Audio-Power-Amplifier-Panel-VU-Meter-DB-Level-w-Back-Light-/231743826824?hash=item35f5022b88:g:jlwAAOSw7hRWPGoC

regards

Spence.

 

[mihailojocic]

Hi,

I can see i wasn't clear, i am using rectifiers with these VU meters.

http://www.ebay.co.uk/itm/DC-AC-6-12V-Audio-Power-Amplifier-Panel-VU-Meter-DB-Level-w-Back-Light-/231743826824?hash=item35f5022b88:g:jlwAAOSw7hRWPGoC

regards

Spence.

Hello Spence!

Did you try these VU meters without rectifiers? I think (but I'm not 100% sure) that they already have ac/dc rectifier inside. Also, if you still need rectifier you should use only germanium diodes because of small voltage drop. 0db is just on 1,775V AC.

Please don't be confused with 6-12V-AC-DC, this is just for lamp!!!

One more thing. This compressor is high quality component! Don't get me wrong, but I think that you should try to find more appropriate VU meters. Used ones maybe, but with stronger quality.

 

[Spencerleehorton]

Need to use germanium diodes rather than silocan and change R51 resistor as VU meters are 650uA!
If I use a 5k pot then tweak to 0db, going to put 600R on output first.

Spence.

 

[mihailojocic]

Output is still to loud! I tried to find mistake, I make some measurements but everything look just fine. I am amateur if we talk about electronics so any help will be something.

Can someone please tell me where to start?!?

 

[Spencerleehorton]

Top tip i was told, when measuring transistors, there should only be 0.6v difference between the Emitter and the base voltage, with this rule you should be able to identify any rogue or troublesome transistors.
I have a few i need to change so in same boat with overloud output on one channel, need to change Q8.

regards

Spence.