[BUILD] 1176LN Rev D DIY

[college101]

OK guys...I have gone threw my capacitors now, and everything is matching up to specs! Im still kind of lost on why I have -8.65 instead of being closer to -10 on the neg rail?

Transistors are being replaced soon!

What else can cause my rail to be off that far?  anybody??

 

[gemini86]

Maybe replace CR6, see what happens.

 

[college101]

YEAH gemini86!

CR6 will be replaced next...I finally figured out most of my voltages on the transistors are Correct, I was just reading them wrong...the only one I think is actually worth investigating now is Q4 which is

0.996
0.497
0.424

I need to check the collector voltage on that transistor again..the voltage is way off...or that cap went bad after I solder'd it in to place...

CR6 does puzzle me... Im getting -8.68 after I connected the A/C ground to the same chassis ground point

I will be installing a dip socket for R44...to just completely take it out of circuit till the final step of calibration...seems like others have done that and had success...I feel like I am going to get this right this time!!  Im close...I can feel it

 

[cwalcott]

hey all,  i've built 2 boxes.  one of them is working fine.  compression works, meters are tracking correctly.  the other box is passing audio but the output is cutting off everything below 300.  the meters appear to be working ok.

i've ruled out the input stage.  i swapped out the input transformer and input t-attenuator.  same result.

i went over the board.  all caps are in the right place and polarity.  transistors are correct.  i haven't done a resister by resister check yet but they should be correct as i built both boards at the same time.

tia,

- chris

 

[college101]

cwalcott! HELLO

Give us your voltages for all the transistors

Give us the dc voltage readings for the powersupply test points(+30 and -10)

What parts list are using

This will get us started!  Hope I can help you...

 

[Nashsound]

I have built 4 Blue stripes and 1 rev D in the last year...something I do, which may be helpfull, is take the time when you inventory your parts or are ready to assemble the board is check all the resistors with a DMM.  Yes, you can look at color code, but the DMM is very fast.  Mouser is very good about their parts packaging, but every once in a while they screw up. I caught one on the Rev D parts, where they hae the wrong resistor value in the bag- If I had'nt checked it, it would have taken me for ever to find it once installed on the board.
Just my 2 cents worth, yours for free

Jeff

 

[college101]

Nashsound is right

I checked and notated every value of each and every part BEFORE I stuff my boards, if something fails, then I can compare to my previos reading...its just note taking

 

[imo]

I came back from a tour to find a non working 1176D. Opened it up and found a toasted power section. I think a couple of pins had shorted out on the ratio board. Replaced the faulty power components, got the power rails up and biased the unit. Was able to bias the fet and zero the meter, but noticed some strange behavior when trying to adjust the tracking. Different ratios were affecting the "zero" position of the meter when changed. Went back through the board, thoroughly re-cleaning it, checked again, and found that the DC bias(with no AC signal) was shifting on Q11-Q13 depending on where the release control was set. Replaced C19 and C20(tant caps), fets,  and the low leakage diodes, but i am still having the same symptoms. I could replace the transistors, but would love to understand what is happening as opposed to just subbing in parts with the hope of finding the problem..
Any ideas?
Ian

 

[college101]

I give up...I have gone threw every part, re checked everything, and nothing...I replaced cr6, and it still measures -08.65 with a new NTE zener diode...

I started checking continuity again, and everything checks out...

Still cant adjust R44...

Think I have to go to a Tech cause nothing is wrong with it...except the tracking adjust does not work

It would be nice if some 1176 pro's got on here and gave me some advice...so far this has been a fail

 

[cwalcott]

hey guys, i need a little help with the procedure to test out my transistors.  i have a fluke digital multimeter and i bought a transistor meter when i started this build to match the 2 FET's.  now that they are all on the board, how do i test them?  i'm testing for voltages, right?  how do i do that?  sorry for the lame newbe question.  i'm not an ee.

thanks!

- chris

 

[imo]

Chris,
you need to match the fets out of cicuit. there are a couple of simple schematics that use a meter and a power source and a couple of resistors. If you want, you can get them from Mike @ Hairball
search for "fet matching"

 

[Echo North]

hey guys, i need a little help with the procedure to test out my transistors.  i have a fluke digital multimeter and i bought a transistor meter when i started this build to match the 2 FET's.  now that they are all on the board, how do i test them?  i'm testing for voltages, right?  how do i do that?  sorry for the lame newbe question.  i'm not an ee.

thanks!

- chris

Good recent discussion here:
http://www.groupdiy.com/index.php?topic=646.3320

 

[cwalcott]

sorry, i wasn't clear.  i've already matched my FET's off board with the transistor multi-meter.  i'm now going back and rechecking voltages on the stuffed parts.  i noticed that college101 reported 3 numbers for Q4.  i would have thought that you could only get 2 numbers for BE and BC.

 

[cwalcott]

hey college101, on the unit that works for me, i was unable to adjust R44 as per the mnats video or the JBL instructions.    the meter does appear to be working correctly for me.  VU and GR both tracks as i'd expect.  turning GR off with program material going through sets the meter to 0.  and slam mode goes into it's expected crazy mode.

 

[gemini86]

sorry, i wasn't clear.  i've already matched my FET's off board with the transistor multi-meter.  i'm now going back and rechecking voltages on the stuffed parts.  i noticed that college101 reported 3 numbers for Q4.  i would have thought that you could only get 2 numbers for BE and BC.

You're collecting voltages between each pin and ground. 3 voltages.

 

[Biasrocks]

It would be nice if some 1176 pro's got on here and gave me some advice...so far this has been a fail

I wouldn't worry to much about the -10 rail being slightly low. I'm fairly certain that mine is a bit low in one of my working 1176 builds.

Did you put a 5K trimmer in place of the 2K yet?

Regards,
Mark

 

[cwalcott]

thanks gemini86.  that's what i thought.  one more question.  do i collect these voltages with the power on?

- chris

 

[college101]

Biasrocks-Hello     

cwalcott-  3 voltage off-    check each pin  = YES = you must have the power ON to check the voltages

I was planning on adding the dip sockets to the R75 and R44 to make things easier, as well as adding the 5k to the R75

I'm not convinced that is going to solve the problem...

I am showing compression in GR mode, its just at -20, with compression "ON" via the built in attack switch...

I am sure my compressor works fine, I just want to be able to accuartely track my gain reduction

I tried putting a 5k in for R44 and that did nothing..Will try it in the R75 position next
I did add a ground to the Center Tap A/C line off of the board(hum went away)

 

[gemini86]

thanks gemini86.  that's what i thought.  one more question.  do i collect these voltages with the power on?

- chris

yes. You'd get 0 across the board without power.

 

[cwalcott]

i added a 5k trim pot on R75.  i also swapped out every trim pot for single turn pots instead of the endless turn pots that the BOM lists.  makes things a ton easier.  for whatever it's worth, i was also unable to calibrate R44 but i am able to track GR.  seems weird to me.