All things G1176 - the new "repost" thread.

[maxheadroom]

another thing, is the line-amp working when R34 is not populated?

on the collector of Q5 i have no signal. but on the emitter i have.

with R34 i have output signal, without i don't.

 

[gswan]

[quote author="buschfsu"]nice job, and thanks for your help! lots of the pics come up red x's for me though. (IE 6)[/quote]

I don't have IE6, so I can't replicate what you are seeing. Works OK in IE7 and Firefox though.

 

[gswan]

[quote author="maxheadroom"]another thing, is the line-amp working when R34 is not populated?

on the collector of Q5 i have no signal. but on the emitter i have.

with R34 i have output signal, without i don't.[/quote]

R34 is the feedback resistor for the line amp section. I'd suggest fitting it if you want it to work.

 

[maxheadroom]

with the R34 resistor ore not i have no signal on the Q5 Collector, only on the Q5 Emmiter.
are you sure your plot on your site from "base of Q6" are right?

 

[gswan]

[quote author="maxheadroom"]gswan, my line-amp has a gain of approximately of +3,5 dB.
i use for Q8 and Q9 the BD135 and BD136 types.
in your part list you have BD139 and BD140 types and a gain of you line-amp is about +10dB.

for Q6 and Q7 i use the same as you BC560. also for Q5 (BC107).

is it the reason of more gain when you use the other BD types?[/quote]

Shouldn't make any difference. The gain overall stage is set independently of the Hfe of the transistors (providing suitable types are used).
BD135: Vceo = 45V, Vcesat = 0.5V, Hfe = 40~250
BD139: Vceo = 80V, Vcesat = 0.5V, Hfe = 40~160

I use BC547 instead of BC107 (they are slightly better and more available)
BC547: Vceo = 45V, Vcesat = 0.25V, Hfe = 110~800 Ft = 150~300MHz
BC107: Vceo = 50V, Vcesat = 0.25V, Hfe = 110 ~ 450, Ft = 100~220MHz

Are you seeing distortion at the output? Maybe you need to check the feedback resistor (R34) and also R33/C13.

 

[gswan]

[quote author="maxheadroom"]with the R34 resistor ore not i have no signal on the Q5 Collector, only on the Q5 Emmiter.
are you sure your plot on your site from "base of Q6" are right?[/quote]

Yes. If you have signal on the base of Q5 and it's being driven into conduction then you have current flowing through C-E, so you must have signal on both the collector and the emitter. Make sure you have correct values for C12/R37 or you will severely reduce the signal on the collector.

 

[kenrinc]

[quote author="gswan"]

Vgs is the gate-source voltage.
The source is connected to GND and you are using the trimmer to vary the voltage from 0V to -10V (or whatever -ve voltage you connect) on the Gate, relative to GND.
You need to measure both Vgs and Vds to plot the relationship.[/quote]

Ahh... got ya. So you actually need 2 power sources one +/- 10v and one negative voltage to Gds? I didn't see a trimmer or pot anywhere. Although I think I see where one might be. Is this the 10k guy?

Ken

 

[gswan]

Yes Ken, you need a positive supply for the drain and a variable negative supply for the gate. Hence the +/-10V (or you can use two 9V batteries to do this).

The 10K trimmer symbol is the trimmer that you need to adjust. Squiggly line symbols were dropped back in the 70's for more CAD-convenient ISO rectangles.

 

[maxheadroom]

[quote author="gswan"][quote author="maxheadroom"]with the R34 resistor ore not i have no signal on the Q5 Collector, only on the Q5 Emmiter.
are you sure your plot on your site from "base of Q6" are right?[/quote]

Yes. If you have signal on the base of Q5 and it's being driven into conduction then you have current flowing through C-E, so you must have signal on both the collector and the emitter. Make sure you have correct values for C12/R37 or you will severely reduce the signal on the collector.[/quote]

thanks gswan for your answer!
i will remove Q6, C12 and R34 and measure the collector signal on Q5...

 

[ilikeit]

good morning
I have a problem with my 1176
I try of desire calibrate but the procédure does not work
the vumeters panics but me does not hear compression
the level is less strong but it is all
the button of ratio has no very active

somebody has already had this problem?

 

[maxheadroom]

gswan, i did the configuration that i told above.
disconnect C12, Q6 and R34.
i measure with a scope and made a foto:

input voltage (before C10) was 200mV

then a simulate the line-amp stage with a software (electronic workbench)
i know that software for many years ago, but for this simple circuit its no problem.
the components are also in the library.
in this condition i have the same result.

when i simulate the whole line-amp stage (with all components) with the software i measured less voltage on the base of Q6 than the base of Q5. (~ -40dB)
on the emitter of Q5 i read exactly the same as on the base of Q5.
i also read the gain of the whole stage, and its ~10dB

are you really sure that you don't swap collector and emitter of the Q5 during your measurement?

 

[gswan]

You are correct, my overlay diagram had c and e labels reversed so I had measured the Q5e instead of Q5c for the Q6b signal. I've updated the site with the new waveform (I updated all the waveforms for this section to be consistent with any signal amplitude changes).

It is, as you point out, significantly lower in amplitude, however the output and other waveforms are still the same.

I'm not sure what the waveform shown on the scope is measuring. Is this what you are seeing on Q6-b?

 

[gswan]

[quote author="ilikeit"]good morning
I have a problem with my 1176
I try of desire calibrate but the procédure does not work
the vumeters panics but me does not hear compression
the level is less strong but it is all
the button of ratio has no very active

somebody has already had this problem?[/quote]

Start doing some measurements and let's look at the numbers.

 

[Echo North]

Can someone tell me what the VU meter does in "Bypass" mode on the Gyraf/Mnats boards?

On the original the attack knob housed the bypass mode then you could select +4 or +8 in the push button section. Since the bypass has been moved to the push button section on these boards what is the default metering in bypass? +4, +8, none?

Thank you for the info!

Mike

 

[maxheadroom]

the waveform shows the collector of Q5, WITHOUT Q6, C12 and R34.

also the DC point at the Q5 collector says a lot. the working point is very high, so for correct working the voltage can't be higher as ~ 2Vss.
(28,6Vdc + 1Vs = 29,6V).

for my trouble i fixed it. i must say it was to fault in the circuit
it was only a bad measurement. i measured it with a multimeter and yesterday i measured it with the scope and it was NOT the same.
my multimeter can't read AC perfect. ( it's a cheap one)

i can all of you recommend to measure it with scope :grin:

 

[ilikeit]

hi
i cheked the connection between the number
it s ok
for the measurement i can use this value?
http://www.axtsystems.com/index.php/projects/34-1176ln/57-1176lnproblems
thanks a lot for you answer!

 

[kenrinc]

Still trying to get my 1176 up and running. Originally had an issue with the meter pegging in GR mode. I thought this had something to do with pad 18 connection to the meter board but that is OK but I noticed that if I turn Qbias clockwise the meter will come back to zero. Mnats rev J. OEP in and out trannies.

Problem is I still can't go through the calibration procedure because I can't get enough level into the unit to deflect the meter (at any meter switch setting). After setting the unit up for the Qbias adjustment procedure and setting Input and Output to full CW, I can't get the meter to go past about -10 (Sifam AL19).

I checked all the transistor voltages against gswans table and they all check out OK. Nothing off by more than 1 volt.

If I input a tone into the unit I can hear tone coming out but I can't get enough level. Using an external CD player with headphone volume up all the way. Going to pins 2 and 3 on input. Battery powered amp on output pin 2 and 3.

Have signal at input pot, both wiper and cw lug. Also have signal at Output pot. Not sure where to go from there.

Any help appreciated.

Ken

 

[gswan]

[quote author="kenrinc"]
I checked all the transistor voltages against gswans table and they all check out OK. Nothing off by more than 1 volt.
[/quote]

Ken, 1 volt difference is too much for many of these DC bias settings. Which ones are really out?

I'm not sure what the circuit looks like for the transformer input version, since I've only been interested in the transformerless input one.

What level of signal have you got on each side of the transformer?

What signal level do you have at Q1-d?

What is Q1 vgs value? If it is conduction (ie Qbias not setup correctly, or a poor FET choice) then it will attenuate the signal constantly at this point.

 

[ilikeit]

hello
any compression with my g1176
i tested the PSU i have 30.6v & -9.83V DV
i checked all my number between the PCB it s ok
i checked my Q
q2 1.036 1.75 0.545
q3 1.755 12.56 1.166
q4 12.56 30.56 11.99
q5 4.943 28.79 4.507
q6 28.80 15.00 29.35
q7 29.35 15.00 29.95
q8 15.00 30.56 14.4
q9 13.68 0 14.27
q12 4.515 15.07 4
q13 15.06 30.56 14.50
q14 4.473 16.71 2.93
q15 16.7 30.56 16.2

it s ok no??
and what is the E connections near Q8 & Q9?
thanks

 

[kenrinc]

gswan,

Thank you for the help. Here are the numbers that I get:

Q2 1.03 1.73 .53
Q3 1.7 12.4 1.13
Q4 12.4 30 11.8
Q5 4.84 28.3 4.4
Q6 28.3 14.4 28.9
Q7 28.87 14.47 29.5
Q8 14.4 30 13.8
Q9 13.1 .001 13.7
Q12 4.58 14.9 4.04
Q13 14.97 30.04 14.4
Q14 3.48 17.42 2.92
Q15 17.42 30.04 16.8

Q1 has .005 at b, .375 at c and .001 at e. I haven't made the setup to match FETs yet so haven't gone through that process.

Thanks

Ken