Lo-D HA-410

[sesebe]

Hello friends,

I started to repair an untouched Lo-D HA-410 amplifier.
Unfortunately it has a loud hissing noise on one of the channels.
Can anyone help me with a service manual or a diagram for this amplifier?

Thank you!

 

[sesebe]

I receive a very fast response with link to the schematic in a different forum (elforum).
The topic can be erased.
Thank you!

 

[dreamth]

Maybe unstable sziklai on one channel...Looks cool for restoring anywway: https://audio-database.com/Lo-D-HITACHI/amp/ha-410-e.html

 

[sesebe]

No, I was wrong. The hiss is influenced by the volum. And, at the beginning when the muting relay is off (input of final amplifier disconnected) there is no noise.
I suppose that the first input capacitor, 0.1uF electrolitic, is with high leakage.
I will change all electrolitic capacitors in the signal line, until 10uF inclusive, with film capacitors.
Tu nu ai mai întrat pe forumul romanesc.

 

[sesebe]

In the end it turned out to be a very loud transistor: 2SC1344 (Q601).
I changed it on both channels with 2SC2240.
I'm thinking of changing the Q602 as well.