SWR Workingman's - distorted

[paspao]

Now I do feel stupid, of course the ends of Q5 will be the same as the driver bases, they are the same points in the circuit. Oh well, I am getting old.

SO we have low distorted output. That seems reasonable at Q5. Have we scoped a sine wave through the amp?

Hi Enzo, more than one year after I have the same problem as Lowel.
I'd read lots of yours post and I think you know about it, so, what do you think about what Loewl said?

Vb Q3= 78 mv -> Is it enough for biasing Q3 + Q4 ?

The measures over the (0.1 Ohms) are 0v and 5mV for Q4 and Q10 respectively. No bias on Q4.
All components are OK, and the sound is low and distorted.

At the out the V= -0,28 V (since Q4 is not conductig)
If I move the bias pot, Q4 begins to work, but Q10 is overexcited.

Thank you Enzo, and also to anybody who can help me.

[drumlessons]

Hi, I know this was a couple years ago, but do you still have the WM 12 amp? I have one and I'm having similar problems.

[J M Fahey]

I suggest you start a new thread and describe what happens to yours.
Good luck.

[drumlessons]

Thanks Fahey. I am trying to see if anyone has pics of the inside of the amp. I'll post some to the other thread you responded to. I really appreciate your help. Peace

[MstrB]

Don, this bias procedure says to do it at 2ohm but the amp says 8ohm min, what am I missing here?

[g1]

The 8 ohm min. is for the ext. speaker. So the minimum load for the amp would be 4 ohms. However, they choose to set the bias at 2 ohms. They specify setting the bias with 2V rms into 2 ohms. That is two watts output, so the amp isn't going to overheat and burn up. Under normal use you would not want to run less than a 4 ohm load, but for the bias procedure at 2 watts output, 2 ohms is ok.

[MstrB]

Thanks, thats what I hoped was the case. Always better to check first tho. Didn't want to blow the outputs by being hasty.