Adjusting the M250

[@fundum]

Hi,

For some time I've wanted to build a powerfull amp. Last year during the summer holiday, I've found the schematic for an amp, the M250 from marcus. This amp has been discussed in a few threads here.

http://www.astro.uu.se/~marcus/private/m250.html

Only a few weeks ago I began building the amp. Now he's allmost completed. Yesterday I tested the amp, and it worked.
Since this is my first big amp project, I have not many experience in this. I would like to know how I can be sure that the amp is biased properly (I mean, to which point I have to adjust the pot in the schematic)?
Also, anything about wirering a power amp and other hints would be appreciated.

Thanks,
Sander

 

[peranders]

If you have an oscilloscope you can measure at the base of T8 and the output. Apply signal for getting 1-2 volts out. Just trim until the two sinus or triangle curves look alike. This is one way. You can also use your ears and if you do that you will notice that the amp will run almost in class B!

 

[li_gangyi]

haha...I've built that amp...I kinda like it...but with some mods...first I didn;t use the to-3 stuff...flat packs were easier to mount...but I use a real big heatsink and a 12V fan to be sure I wun cook anything...no PCBs were used on mine...I simply wired up and screwed everything on the heatsink...sleevling was used if the connections were long...I have no problems with it wad so ever...but I suppose I could really do it a favour by putting it in a case or something...I'm running it without a case now...lolx...