The official G9 help thread
- Thread starter gyraf
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Help Support GroupDIY Audio Forum:
Kingston
Well-known member
I can't imagine how a faulty or wrong capacitor could cause such a clean tilt.
But a broken transformer, or one connected wrong certainly can.
Double check your transformers, input and output, how you've connected them, or if you actually have the correct types installed. Or maybe even connected mirrored?
But a broken transformer, or one connected wrong certainly can.
Double check your transformers, input and output, how you've connected them, or if you actually have the correct types installed. Or maybe even connected mirrored?
Thanks Kingston, I'll concentrate on that area. I believe OEPs cant be oriented wrong since they have shield pin on one end and it will go to pcb only one way.
Edit:
I checked wiring again and it seems to be correct and measured dcr from transformers and they match OEP spec sheet... Can transformers be still faulty?
I'm retiring for few days and then try to find a spot with a scope where bottom end disappears. The slope seems to be about 6db so it might be some way of resistor somewhere. I don't know if caps can be that way of without remarkable physical size difference?
Edit:
I checked wiring again and it seems to be correct and measured dcr from transformers and they match OEP spec sheet... Can transformers be still faulty?
I'm retiring for few days and then try to find a spot with a scope where bottom end disappears. The slope seems to be about 6db so it might be some way of resistor somewhere. I don't know if caps can be that way of without remarkable physical size difference?
Hi again.
I am running oscilation problems and hum problems now. All the cables are shielded.
Most of the hum noise comes from the potentiometers, could it be some grounding problem?
I guess for oscilation i will try the solution of running the shielded cable to the track.
Thanks!
I will try to give more information to my problems if they keep happening, and trying other things.
Edit: There is additional noise from the balanced input rather than unbalanced input, can phantom power create noise?
I am running oscilation problems and hum problems now. All the cables are shielded.
Most of the hum noise comes from the potentiometers, could it be some grounding problem?
I guess for oscilation i will try the solution of running the shielded cable to the track.
Thanks!
I will try to give more information to my problems if they keep happening, and trying other things.
Edit: There is additional noise from the balanced input rather than unbalanced input, can phantom power create noise?
I'm having some problems with the 48V supply. I can adjust the voltage with the trimmer but only up to 35V and then it stops there, the trimmer is at it's end.
I have 70V DC after the voltage tripler, as seen in the attached image, but it drops to 35V at the junction of R40 and D6. Could it be the zener that is bad or is it something else?
Everything is built into the case and i've been using it for almost a year but decided to add PP now..so i want to be pretty sure what to change before mounting everything apart.
I have 70V DC after the voltage tripler, as seen in the attached image, but it drops to 35V at the junction of R40 and D6. Could it be the zener that is bad or is it something else?
Everything is built into the case and i've been using it for almost a year but decided to add PP now..so i want to be pretty sure what to change before mounting everything apart.
skeld
Member
Hello, I have just finnished my G9 preamp. I have ran the unit for the first time and I am a bit worried about temperature inside with the unit cover on. After 30 minutes of operation I have put down the cover and measured cooler temperature with results 80°C on small coller and 70°C on large one as shown on the picture bellow. I use cover with perforation (picture). I am afraid this temperature is to high for the unit operation, but I think larger coolers will not solve the problem, because the heat will still stay inside the unit. I am worried if I put the unit into a rack between other units I posses no ventilation will be possible and temperature can cause problems. What should be the normal temperature on cooler? Have someone done any temperature measuring?
skeld said:
Hi,
I haven't measured temperatures but 78S12 runs really hot, I'd say mine is propably around 70C too. No idea on TL783 because it is on area where I'm not comfortable to put my fingers to. Ventilation holes aren't for decoration in G9 if I'm not totally mistaken.
Cheers,
MT
skeld
Member
and how do you solve the ventilation of the unit, do you think perforation on cover, like on my picture is enough? Or it is better to make some holes on the back panel as well. I was also wondering to put one large cooler on back panel, outside the unit, with copper bridge connections to the regulators.
Kingston
Well-known member
With that big heat sink even a non-ventilated case is fine. 70 degrees is a "low" temperature with such a big heat sink.
With some more critical projects I have solved this by sticking the heatsink outside the back panel (with a secure hole for regulator wiring to get it outside). But those were regulators working to dissipate at more than 4 amps.
G9 only has to work some 1.2A. Your heatsink is plenty. No need to leave extra space above the rack either.
With some more critical projects I have solved this by sticking the heatsink outside the back panel (with a secure hole for regulator wiring to get it outside). But those were regulators working to dissipate at more than 4 amps.
G9 only has to work some 1.2A. Your heatsink is plenty. No need to leave extra space above the rack either.
barthman.de
Well-known member
I posted some problems here (I think the circuit diagram is different to the pcb):
http://www.groupdiy.com/index.php?topic=39802.0
...found this official G9 help thread to late
Could sombody look to my problem with R44 (my last post at the treatise I linked above) ?
Thank you very much.
http://www.groupdiy.com/index.php?topic=39802.0
...found this official G9 help thread to late
Could sombody look to my problem with R44 (my last post at the treatise I linked above) ?
Thank you very much.
barthman.de
Well-known member
So fast
barthman.de
Well-known member
Maybe I'm confused because I was looking one hour to the part of the pcb with the rotary switches
R 44 is there between the both poles of the "+" - input. But of course you are right - R44 is only between "hot" and "cold". I needed this cause for thought Now I can draw and order my transformer PCB :-*
Good night.
R 44 is there between the both poles of the "+" - input. But of course you are right - R44 is only between "hot" and "cold". I needed this cause for thought
Now I can draw and order my transformer PCB :-*Good night.
aclac
Active member
HI. I had finished G9 and it sounds fine and work well, but... CH1 phase reverse gives signal only one position (+), and (-) pos is death. I was wondering how does this circle work. If I take closer look component layout pdf, I notice, that output transformercoils are connected serial and 10k resistor is between legs, OK. But when I look electrical drawings of connection... hmmm. Output trafo is connected so, that only one output coil work in one direction (can this picture in gyrafs side be wrong)? It is very difficult find solution my problem, because I can't undestand pictures. Btw. I measured, that output 2 resistance is about 40 ohm (-pos) and same (+pos), and output 1 has 0 ohm (-pos) and 40 ohm (+pos). It seems, that I have short circuit somewhere... please tell me where. I wan't loose out this phase reverse SW, before some give me clear thoughts? Aclac
skeld
Member
Kingston said:
Thanx for help
barthman.de
Well-known member
@aclac
Yes the original circuit design of the Gyraf-site seems to be wrong for output transformer wiring but the PCB is right. The PCB shows it right the output of the transformer must be connected serial. Maybe my drawings will help you.
(look at my discussion http://www.groupdiy.com/index.php?topic=39802.0 )
Yes the original circuit design of the Gyraf-site seems to be wrong for output transformer wiring but the PCB is right. The PCB shows it right the output of the transformer must be connected serial. Maybe my drawings will help you.
(look at my discussion http://www.groupdiy.com/index.php?topic=39802.0 )
aclac
Active member
barthman.de said:
Thanks. Your picture is good, but almost right... In the PCB first is output trafo and resistor R32 (10k). Then is coming SW with R44 (10k) (but seems to be other way, than your picture)... hmm, it doesn't matter. It is only little bit tricky to understand. In my case the lorlin SW seems to give short circuit in the output, when phase is inverted. Can this switch do so? It is guite big job to change new switch or other position, and maybe it can wait...
If you or somebody have some ideas, please let me know. Aclac
Harpo
Well-known member
Maybe you placed the end stop washer when the lorlin was not set to its full ccw position. Lorlin now switching between positions 2/3 instead of 1/2.aclac said:
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