Can you post some pics ?
Is the TX near the amp boards ?
Can you post a schematic with your GND layout ?
Is the TX near the amp boards ?
Can you post a schematic with your GND layout ?
Tx & choke in a separate box as per pics
Schematic
GND is a copper bus solid core
AC gnd to chassis TX, gnd chassis Tx to GND solid core bus phono RIAA.
After + Salas HV reg 10nF to gnd phono RIAA chassis, Left & Right gnd 10nF to gnd phono RIAA chassis.
Schematic
GND is a copper bus solid core
AC gnd to chassis TX, gnd chassis Tx to GND solid core bus phono RIAA.
After + Salas HV reg 10nF to gnd phono RIAA chassis, Left & Right gnd 10nF to gnd phono RIAA chassis.
Attachments
Where does your schematic GND connect to chassis GND ?
Why the Reg 10nF to chassis GND ?
My suggestion is drawing the GND setup including the star GND on the chassis and the wire coming from there to the back plate. It is very difficult to see everything in the pics.
ECC88 pin 9 connected to solid core copper bus GND.
All inputs & ouputs signal GND connected to solid core copper bus GND.
Salas GND output connected to solid core copper bus GND.
Tonearm GND connected only at the Hagerman Piccolo MC pre-pre as per Salas advice.
All inputs & ouputs signal GND connected to solid core copper bus GND.
Salas GND output connected to solid core copper bus GND.
Tonearm GND connected only at the Hagerman Piccolo MC pre-pre as per Salas advice.
Last edited:
Only hum right channel when ECC88 is connected😕
I changed the ECC88 with at least 3 differents tubes & still the hum😡
It's possible to fix the hum disconnecting pin 9 ECC88 of gnd?
I changed the ECC88 with at least 3 differents tubes & still the hum😡
It's possible to fix the hum disconnecting pin 9 ECC88 of gnd?
Last edited:
I use 4.7uF instead 3.3uF
I have connected pin 9 ECC88 to gnd bus solid core copper and pins 4 & 5 connected togheter to filaments & pin 9 to filaments in ECC83.
I have hum in right channel but when I diconnect the ECC88 tube the hum disappears it's possible to fix disconnecting pin 9 of gnd?
I have connected pin 9 ECC88 to gnd bus solid core copper and pins 4 & 5 connected togheter to filaments & pin 9 to filaments in ECC83.
I have hum in right channel but when I diconnect the ECC88 tube the hum disappears it's possible to fix disconnecting pin 9 of gnd?
Hi,
You mean that if you disconnect pin 9 at the ECC88 the hum disappears?
You have fitted gridstopper resistors to the ECC88 grids?
Ciao T
You mean that if you disconnect pin 9 at the ECC88 the hum disappears?
You have fitted gridstopper resistors to the ECC88 grids?
Ciao T
Hi,
Well, of course that stops the hum, but the signal too, so it is not very not useful.
Hum in Phonostages is almost always bad layout, shielding or grounding.
I suggest you systematically short beginning with the inputs, working towards the outputs, to see where the hum gets in.
Ciao T
Well, of course that stops the hum, but the signal too, so it is not very not useful.
Hum in Phonostages is almost always bad layout, shielding or grounding.
I suggest you systematically short beginning with the inputs, working towards the outputs, to see where the hum gets in.
Ciao T
I would experiment lifting the 10nF caps off the gnd.
As for pin 9, it seems to be a shield... I guess you can experiment lifting it from GND also.
I am not an expert in this area... Hope Salas could help you here.
As for pin 9, it seems to be a shield... I guess you can experiment lifting it from GND also.
I am not an expert in this area... Hope Salas could help you here.
Logical checks. Had sound and sound stopped? What has got changed meantime? Those 10nF caps are supposed to go from input RCA's rings to chassis locally, not in line with any signal. Rings should be meeting signal ground also with the coaxes. Is the same source playing both channels in another preamp? Connections, all secure? Construction, all secure? Tubes? Bias voltages? Etc.
Gotcha HV B+ 95VDC instead 260VDC, LV filaments 6.3V, I tried to fix to 260VDC to see if noise disappears but trimmer only reach 130VDC. Main Tx 240VAC choke 10H 200mA. VDC in reg 260VAC, reg isn't working OK
Last edited:
Something in th reg is damaged because with the 15K dummy load only reach max 130VDC, all 3 LEDs are shining, the trimmer can go down for less VDC, both mosfets are hot, any resistor burned, can be SK170 in the Vref or any other idea where can I start?
Last edited:
- Status
- Not open for further replies.