All things G1176 - the new "repost" thread.

[a2d]

on the low side of the release pot there are 2 wires one goes to the ratio board and the other goes to pad 18
nothing on the wiper except the resistor,
on the high side of the release  pot  there is 1 wire that goes to the attack pot
on the low side of the attack pot there is a single wire that goes to pad 19
on the wiper there is a resistor and a cap
on the high side of the pot gets connected to the release pot high side

everything seems to be in its right place, unless I'm missing something

 

[a2d]

for the tracking adjustment you don't change the level on the 1176, you turn up your source input (OSC)

Interesting. I did not read that in the calibeation pdf. If it says to do that it certainly isnt clear to me.

right from gyraf site:

1: "Q Bias". This is set by bypassing the unit, putting through a signal, adjusting in- and outlevel so output is around +1dB, and adjusting the trimmer untill a level drop of 1dB is acheived. This sets the FET start point in the beginning of it's conducting range.

2: "Dist. trim". Bypass the unit, input a ~1kHz, ~0dB signal, set unit gain to unity (by input- and output controls), and set trimmer for minimum distortion. If you have no dist.meter, simply set at middle position. Somehow this is not an important adjustment soundwise.

3: "GR meter Zero". No input signal. Meter switch in GR mode. Adjust untill meter reads 0dBVU.

4: "GR meter Trck" (tracking). Set ratio to 1:20, set Meter to bypass. Input a 1kHz, 50mV signal. Set input level to ~12'oclock. Set output level so you get 50mV at the output also (now you have unity gain). Now set the meter switch to "GR". Slowly turn up the level of your input signal (at the signal source, not with the input level control) while you monitor both input- and output levels with a voltmeter. When you reach a point where output level is half the input level, you have 6dB of gain reduction in the unit. Now set the "GR meter Trck" trimmer so the VU-meter reads -6dBVU. Remove input signal and (re)set "GR meter Zero" for a reading of 0dBVU. This calibrates the gr indication.

 

[Chrome Heart]

Thanks a2d. Its certainly clear on the gyraf site. The adjustment procedure I have is not clear on that. It certainly makes more sense.
Im finishing the FPE panel design today, when I get it installed Ill post a pic. Thanks to everyone for the info. ;D

 

[a2d]

can anyone help me out on this issue, when turning the release pot it affects the meter position, in GR or Bypass
as for the wiring it looks fine

Why would the release pot affect what the meter is seeing????


Maybe the moderator could help????

 

[a2d]

ok maybe I found something on the BOM it states R18 is 22k
on the schematic it says 3.9 M??? any idea
ok well I switched it out to the 3.9m still the same thing
grrrrrrr  the lack of knowledge, makes DIY very frustrating

 

[ricothetroll]

Hi ! I just got some Lundahl LL1517 output trafos and I was wondering if they could substitute the LL5402 that Jakob recomends. I did some researches on the forum but didn't find an answer that satisfies me.

Comparing both datasheets I found those noticeable differences :

Static resistance of primary :
- LL5402 : 30 Ohm
- LL1517 : 9.2 Ohm

Optimum source impedance :
- LL5402 : minus 15 Ohm
- LL1517 : minus 18 Ohm

http://www.lundahl.se/pdfs/datash/5402.pdf
http://www.lundahl.se/pdfs/datash/1517.pdf

How can a source impedance be negative ? Has the push-pull output stage (Q8 - Q9) of the G1176 an impedance low enough to feed the LL1517 ?

http://www.gyraf.dk/gy_pd/1176/1176sch.gif

Thanx in advance !

Best regards.

Eric

 

[Chrome Heart]

ok maybe I found something on the BOM it states R18 is 22k
on the schematic it says 3.9 M??? any idea
ok well I switched it out to the 3.9m still the same thing
grrrrrrr  the lack of knowledge, makes DIY very frustrating

If its any help, I have a 22K in R18 on my Rev J board.

If there is a video demo of this tracking cal. procedure Id sure like to know. Im getting the -10 db drop in GR mode when I switch the attack on and off but not in vu mode. From what I can make out, thats where Im supposed to see it. uugghh, I have a headache.

I did an A/B with my reissue and I must say, sonically its pretty damn close.  I used the 5532 input and it seems a bit, not much, cleaner or brighter. All functions seem to behave almost identical, and overall Im very pleased with it.

 

[gswan]

ok maybe I found something on the BOM it states R18 is 22k
on the schematic it says 3.9 M??? any idea
ok well I switched it out to the 3.9m still the same thing
grrrrrrr  the lack of knowledge, makes DIY very frustrating

R18 should be 22K. Don't know what schematic you are looking at, mine says 22K.

Check R79 and make sure it is 270K (on the release pot).

 

[a2d]

yes 270k in there.

 

[user 37518]

when turning the release pot it causes the meter to swing from +2  to -20?? has anyone had this problem??
when  in GR mode or in bypass mode

Brush the ratio board with some cleaning solution or isopropylic alcohol, im 90% sure that your pcbs are dirty somehow...

 

[a2d]

ok I tried that, still the same thing going on

 

[Chrome Heart]

Correct me if Im wrong, but Im assuming if the tracking isnt calibrated correctly it has no audible effect. Im ready to give up.

 

[gswan]

That's correct. The metering is aside from the signal chain and is not even required for the unit to operate.

 

[a2d]

don't give up, I'll try and help you out, I know this place can be hard to get help, but hang in there ,,,  I'm still waiting to find help for my issue............

for the tracking adjustment you need your output level 1/2 the input level, at that point you will have 6db in gain reduction,
use the tracking pot and adjust your meter till it reads -6

Correct me if Im wrong, but Im assuming if the tracking isnt calibrated correctly it has no audible effect. Im ready to give up.

 

[a2d]

does anyone have any Idea why the release pot would affect the meter,
or maybe could someone tell me how the fet in Q10 works?

 

[Chrome Heart]

Well I decided to switch out the trim pots (I had extras) and lo and behold, it does what its supposed to. I swear I read over the adjustment procedure 100 times over the last few days and  I was convinced it just wasnt sinking in. When I set the unit up for tracking adj. after switching the pots out and rebiasing, I was expecting the same behavior. But what a shock when the meter actually dropped to -6 after a very slight twist. A bad component can really ruin your weekend.
Thanks a2d. I know your having some frustrations of your own.

 

[gswan]

does anyone have any Idea why the release pot would affect the meter,
or maybe could someone tell me how the fet in Q10 works?

Get out the scope and start probing around the Qbias pot and release pot areas, with GR bypassed. There should be no output from the GR amp in this case, so your pot is wired to somehow alter Qbias. Check for either wiring or component errors.

 

[Chrome Heart]

Works great, now I just wait for the FPE front panel.

 

[gswan]

yes 270k in there.

R48 is a 3.9M though. Is this one correct?
Check the components around the Qbias pot (R82, R83, R81).
Check what is happening at point (7) when you turn the release pot.

 

[a2d]

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