Good evening!
I have built a Mullard 3-3. But I have problems in the power supply and generally with the voltages. I'm doing a test without tubes and I have much too high voltage already at pin3 of the EZ81 ... 400v?!? (transformer has 300-0-300)
With the tubes installed the voltages are also too high. Over R13 I measured ca 60V with 150V (normally we have around 230V here in Austria) mains voltage set on my variac !?! Also the anode voltages at EL86 and EL84 are too high?! Wiring error?
The OPT has a blue 0 ohm, red 5kohm cable (info on the OPT, company Primary Windings from UK ). The 5kohm cable hangs on the anode pin7 of the EL84. The 0 Ohm Blue Cable is connected to pin 3 on the EZ81 ... Right?
EZ81 tube broken...electrolytic capacitors or resistors faulty?!
The center tap of the mains transformer is connected to the neg. Pole of the first electrolytic capacitor and from there it goes / is connected to the case and protective cable....
What am I overlooking? Shred everything out...?!
I use this schematic
https://www.heatedcathode.com/3w-si...-amplifier/model-1955-gen2-el84-se-amplifier/
I have built a Mullard 3-3. But I have problems in the power supply and generally with the voltages. I'm doing a test without tubes and I have much too high voltage already at pin3 of the EZ81 ... 400v?!? (transformer has 300-0-300)
With the tubes installed the voltages are also too high. Over R13 I measured ca 60V with 150V (normally we have around 230V here in Austria) mains voltage set on my variac !?! Also the anode voltages at EL86 and EL84 are too high?! Wiring error?
The OPT has a blue 0 ohm, red 5kohm cable (info on the OPT, company Primary Windings from UK ). The 5kohm cable hangs on the anode pin7 of the EL84. The 0 Ohm Blue Cable is connected to pin 3 on the EZ81 ... Right?
EZ81 tube broken...electrolytic capacitors or resistors faulty?!
The center tap of the mains transformer is connected to the neg. Pole of the first electrolytic capacitor and from there it goes / is connected to the case and protective cable....
What am I overlooking? Shred everything out...?!
I use this schematic
https://www.heatedcathode.com/3w-si...-amplifier/model-1955-gen2-el84-se-amplifier/
You write that your transformer has 300-0-300 V. But in the schematic you linked to the transformer has 270-0-270 V. So it's logical that your B+ is too high.
In the original schematic you can see R15 between the EZ80 and the rest of the amplifier. The value has of R15 has to be tweaked until B+ is 290 V when the amplifier is working with no input signal.
Mullard 3-3
In the original schematic you can see R15 between the EZ80 and the rest of the amplifier. The value has of R15 has to be tweaked until B+ is 290 V when the amplifier is working with no input signal.
Mullard 3-3
