I made a copy of Marshall jcm800 , with a little modify at output stage (use 12ax7 as power tube).
My problems are ;
1. it very noisy .the noise goes up as i turn up the master volume and gain , even in clean channel.
2. All my fuses are blown .The power transformer rating is : input 100v ,ouput 200v 80ma and 6.3v 2A.Output transformer is 5w primary 10k ohms, secondary 8ohms.Pre amp tube are 12ax7 x3 , 12au7 x1. I used 250v 100mA fuse for F2 and 125v 300mA fuse for F1.Every i connect the amp to AC the fuses are blown , but if i use cooper wire instead it works but very noisy .
Can anyone help me with troubleshooting please !
Thanks in advance , and sorry for my bad English !
My problems are ;
1. it very noisy .the noise goes up as i turn up the master volume and gain , even in clean channel.
2. All my fuses are blown .The power transformer rating is : input 100v ,ouput 200v 80ma and 6.3v 2A.Output transformer is 5w primary 10k ohms, secondary 8ohms.Pre amp tube are 12ax7 x3 , 12au7 x1. I used 250v 100mA fuse for F2 and 125v 300mA fuse for F1.Every i connect the amp to AC the fuses are blown , but if i use cooper wire instead it works but very noisy .
Can anyone help me with troubleshooting please !
Thanks in advance , and sorry for my bad English !
Thanks! What do you mind by ac-powered filament? (sorry for my bad English) .I used diode bridge to convert AC to DC , i uploaded the power transformer schematic below .
this is the audio file i recorded : https://drive.google.com/file/d/0B17vOl3Q8vbJck5nMzhibVpsMEE/view?usp=sharing
Attachments
Thanks !
i did as you dais and the noise is completly gone . <3
i have one more question : can you help me choose value for the fuse F! and F2 please !
Your circuit shows AC heaters, and a rectifier bridge for the main DC supply rail.login721 said:
Heaters, whether AC or DC, must have a reference voltage (which may be zero i.e. circuit ground).
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