[RuiCanela]

I have this amp like this. However a friend of mine moved the adjustment pots near the valve. The sound has changed for the worse. How do adjust the bias voltage properly using a multimeter. Help please



 
 

 

[Avro_Arrow]

The post here shows the correct bias voltage.

 

[RuiCanela]

Thanks, I will try it.

 

[anael28130]

Hello, I've the same item since 3years ago. Now, it doesn't work. I bought 2 valves and worse. It go on ON but after some seconds (10), all leds and valve go off and sound is very bad and off. I search schema and voltage to find problems and try to repair this good headphones amplifier. Thanks. (excuse my bad english, french froggy...lol). anael

 

[Avro_Arrow]

replace the power supply

 

[anael28130]

Hello,
 
Thanks for your reply. I try this and say you if it's good.
Regards.
anael

 

[anael28130]

Hello, After a long silence, i come back with my problem; i've replaced power supply and valve but sometimes, it works for many hours and sometimes, it works about 10 mn

.
I tried to work with different headphones or with a preamp before headphones: same problem. I think to buy another but my money is limited now. What's stable amp with a correct cost?
Thanks and regards,
anael

 

[anael28130]

Re-hello, On afternoon, i tried to search and perhaps i find it; Radiators are not enough for the cooling of transistors (irf630n). I put a little ventilator and after 3 hours no problem but i'm afraid because the valve is almost cold now. What is the risk except the sound is little metallic on trebble? Use bigger radiators seems to me the best.
Thanks and regards,
anael

 

[looser101]

I believe there have been many reports of power switch failures on that type of amp.

 

[anael28130]

hello looser101, thanks for your help; I'll do change this switch and i'll try so change the radiators because their alu color is came little red and blue (hot temperature).
Regards, anael