All things G1176 - the new "repost" thread.

[seavote]

i hooked up my power transformer incorrectly . now its correct. now im getting 33.7V at cr7(diode befor regulator)  thats good.  but 2V at r87  (directly after the 7824) i assume i fried the regulator. would a fried regulator let some voltage through or could the 2V reading be the result of something else? thanks

 

[audiophreak]

OK ... OK ... and my Newbe-ness shines through once again  ;D


  .. so i need a PT with 2 x 24vac secondaries  .. got it  .. now  ;D

 

[audiophreak]

Hello,

  Unless anyone has any other suggestions for U.S. members,  I found this PT , seems more than sufficient, and at a great price too.

http://www.antekinc.com/details.php?p=648

 

 

[jeid]

Ok, I've managed to perform the Q Bias adjustment without problem.

When setting up the meter I'm having trouble.

I can zero the meter, but when I'm turning the attack back on, I can't raise the input level high enough to take it up to -10. Even all the way up doesn't take it up to the correct level. When I switch the attack off again, the level is back up at +3. I've seen that this takes a lot of back and forth, but it seems quite a bit off.

Any ideas?

Checked all the transistor voltages again and they passed on the spreadsheet. Any help would be greatly appreciated. Thanks

 

[jeid]

Further to my above post, my compressor works, it's just the GR meter that isn't calibrating. I'm totally baffled. I bought the meter from Hairball audio, so it's a recommended one. It will swing back and forth when a signal is passed through, but just not accurately

 

[seavote]

bump

i hooked up my power transformer incorrectly . now its correct. now im getting 33.7V at cr7(diode befor regulator)  thats good.  but 2V at r87  (directly after the 7824) i assume i fried the regulator. would a fried regulator let some voltage through or could the 2V reading be the result of something else? thanks

i swapped out the 7824 and im still getting only 3V out of the regulator. does this mean something is grounding out somewhere in the circuit??  any likely causes i should be checking? all diodes and caps checked for direction.  checked for solder bridges and badssolder joints.  are all transistors suspect because i had my power voltage at 48V while it was hooked up incorrectly?i think i know what could be wrong but im looking for someone with more knowledge to give me probabilties so i know what to check for first. any help is appreciated  thanks
8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8)

 

[gswan]

Pull out Q8 and Q9 and see if the rail returns to normal. I'm assuming you already replaced the op amps.

 

[seavote]

never assume i know anything!!! i havent replace any op amps. pulled out q8and 9  now im getting (if i remember correctly,dont have unit  in front of me,wrote it downbut left note at work ))  24V at cr7 and about 27V at r87.  what does this tell me?  replace q8,9???
i'll need to order replcements so im thinking ishould order opamps at the same time,yeah?
thanks for the help..

 

[YourFrndBen]

Hi all!

so I just finished putting together a 1176_revD build; my first "buy your own parts" build.

Shortly after firing it up, R32 burnt out in a sizzle of smoke.

Ive double-checked wiring hookups, component values, etc, but nothing seems to be out of place...

The only suspicion I have is C14, which I used a .033uf/400v 10% Mylar cap...
I found this link on the same cap: http://www.groupdiy.com/index.php?topic=468
At which point I double checked my board, which reads Class: A Output.

If anyone can point my multimeter needles in the right direction, it'd be greatly appreciated!

I can read schematic values ok, but pretty noob when it comes to component/circuit functionality.

Anyone have a similar experience?


-Ben

 

[gswan]

never assume i know anything!!! i havent replace any op amps. pulled out q8and 9  now im getting (if i remember correctly,dont have unit  in front of me,wrote it downbut left note at work ))  24V at cr7 and about 27V at r87.  what does this tell me?  replace q8,9???
i'll need to order replcements so im thinking ishould order opamps at the same time,yeah?
thanks for the help..

I'd suggest replacing the op amps (since you say you applied 48V to them, and they don't really like more than 36V) and also replacing Q8 and Q9 (check orientation and correct holes as well). You can perform a basic hfe test on the transistors you pulled if your meter has this functionality. It will show if the transistors are operating OK. If not you can try a diode test (B-E and B-C) to see if any of the junctions are shorted.

 

[jeid]

Ok, I've managed to perform the Q Bias adjustment without problem.

When setting up the meter I'm having trouble.

I can zero the meter, but when I'm turning the attack back on, I can't raise the input level high enough to take it up to -10. Even all the way up doesn't take it up to the correct level. When I switch the attack off again, the level is back up at +3. I've seen that this takes a lot of back and forth, but it seems quite a bit off.

Any ideas?

Anyone got any suggestions for my problem? Still pretty stuck with this one

 

[gswan]

How closely matched were the FETs?

 

[jeid]

I got them(BF245A's) from Banzai, I'm not entirely sure they were matched. I don't think they were matched at all

 

[Le Roux]

I need help with the second stage of calibration. Gain Reduction Meter Tracking.

I've followed the Axt Systems website, but my attack control does not move the meter.

I am trying to calibrate 3 units, all do the same.

I have also followed, I think it was Gyraf's calibration procedure, and was able to get the -6 dBu gain reduction, however this has nothing to do with the attack control.
This is from bypass to GR mode.

The release control on one unit is able to drop the meter to -6 dBu when in GR mode.

All units appear to be working properly, quiet, and both attack and release controls seem to work, as with the ratio control.
I have checked all my voltages, and they're within reason.

Any help would be appreciated.

Neil

 

[gswan]

I need help with the second stage of calibration. Gain Reduction Meter Tracking.

I've followed the Axt Systems website, but my attack control does not move the meter.

Neil

This procedure assumes you have the GR bypass switch on the attack control. If you don't then it won't work.

 

[Le Roux]

Ahhhh....makes sense!

Thanks for your input.

Neil

 

[gswan]

You can still use the procedure, however instead of using the attack control to switch GR on and off, use whatever other switch you have for this operation.

 

[seavote]

Justa recap of my previous post about an ongoing problem:

________________________________________
Quote from: seavote on May 20, 2011, 05:22:58 pm
i hooked up my power transformer incorrectly . now its correct. now im getting 33.7V at cr7(diode befor regulator) thats good. but 2V at r87 (directly after the 7824) i assume i fried the regulator. would a fried regulator let some voltage through or could the 2V reading be the result of something else? thanks

i swapped out the 7824 and im still getting only 3V out of the regulator. does this mean something is grounding out somewhere in the circuit?? any likely causes i should be checking? all diodes and caps checked for direction. checked for solder bridges and badssolder joints. are all transistors suspect because i had my power voltage at 48V while it was hooked up incorrectly?i think i know what could be wrong but im looking for someone with more knowledge to give me probabilties so i know what to check for first. any help is appreciated thanks
           


pulled out q8and 9 now im getting (if i remember correctly,dont have unit in front of me,wrote it downbut left note at work  )) 24V at cr7 and about 27V at r87. what does this tell me? replace q8,9???
i'll need to order replcements so im thinking ishould order opamps at the same time,yeah?
thanks for the help..


I'd suggest replacing the op amps (since you say you applied 48V to them, and they don't really like more than 36V) and also replacing Q8 and Q9 (check orientation and correct holes as well). You can perform a basic hfe test on the transistors you pulled if your meter has this functionality. It will show if the transistors are operating OK. If not you can try a diode test (B-E and B-C) to see if any of the junctions are shorted.
Now an update:

I replaced q8 and 9 As well as op/amp tl 071  and 7824
Im getting same voltage readings. I’ll have another once over for bad solders or bridges as well as  component orientation although ive checked this all befor.wouldnt be the first time ifound something on the second or third go round.  If as I suspect I find no errors what other components would cause the voltage regulator to only put out 3 volts. I am isolating the regulator. is this correct? It gets very hot.
Any ideas thanks chris v
8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8)

 

[seavote]

BUMP
unit is at my work so i haven't had a chance to give once over (or twice over? this is the 2nd time). but since i had a better Voltage after removing  q8 and9,but only 2V when i replaced them is it safe to assume the problem is some where past Q8 and 9 in the circuit? any particular components or areas i should be concentrating on? thanks for anyhelp
chris v
8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8)  
EDIT:6/20
fire the unit up tocheck some voltages . the regulator fried and the fuse blew. would this info help a knowledgeable troubleshooter? i'm not sure what it is telling me.
PS: i realized i am missing thepcb ground from below the output tranny to earth ground. is this the source of my troubles?
8) 8) 8) 8) 8)

 

[gswan]

EDIT:6/20
fire the unit up tocheck some voltages . the regulator fried and the fuse blew. would this info help a knowledgeable troubleshooter? i'm not sure what it is telling me.
PS: i realized i am missing thepcb ground from below the output tranny to earth ground. is this the source of my troubles?

It means you still have a short somewhere on your 30V rail. You need to find this or you will destroy each regulator you put in. My guess is somewhere in the output amp section, or a wiring short. You could use a bench PSU to it with current limiting switched on to help trace the location without blowing up regulators.