Murdock said:
215V after the drop resistor
6.1V at the heater
I would make sure the regulator is actually regulating and not just passing DC, since thats a tiny, tad low
Measure the voltage on the input pin of the LM317 to see if its about the same as its spitting out.
No need to change the drop resistor imo.
Murdock said:
]The high frequency boost on my first channel does nothing except at 2.1 Khz. This one works...
I thought it would be a capacitor I accidentally touched with the solder iron and it has a melted spot. But the capacitor is in the attenuetor section and this seems to work fine...
Does anyone have a clue where I should expect the error to be?
Are you sure its 2.1kHz? I think you have an error in switch programming - the little programming pin, stuck on the wrong side of the switch in position 6. So when you are in 1, you are really in 6, and in 2, you go to 7, which is not a meaningful position.
Even so, and just for the sport of it, it shouldn't be too hard to trace.
Take a look at the schematic
The HF switch is a 2 pole/6 position switch. (Sort of like 2 switches with 6 positions, moved by one control)
Now, trace what I write in the schematic.
On the first position (2.1kHz), the signal passes through a cap to A1 (two in parallel, but lets call it one to simplify), goes from one pole of the switch to the other (A to C), goes up to C1, and then through
all the inductors in
series (C2, C3, C4, C5 and C6 are dead) and moves on.
On the second position, the signal passes through the same cap, down to A2, A always goes to C, regardless of the position you're in, and now C goes up through C2, which does not go through the first cap, but still passes through the rest of them in series.
(If you switch is programmed correctly, and the working frequency is in fact 2.1kHz).
Looking for trouble ont he first pole.
Capacitor switched in on A1 and A2 is the same, so its not the capacitor, or the signal to the capacitor coming to the input (they work on A1!)
It could be the connection
from the capacitor to A2. So basically, see if A2 is connected properly
Looking for trouble on the second pole
The inductors are in series, and on C1, they are all switched in, so you already know the signal makes its way through all of them.
In the second position (C2), you simply bypass one of them, so you could look for trouble on C2 on the switch.
...but
You say all the frequencies over 2k1Hz are dead, and now that you know how to trace the signal though the schematic, you'll see that a missing signal on the A3/C3 would have to be a bum connection around the cap going to A3, or a bad connection from C3.
Its logically possible that you could have a whole gang of bad connections (fourth, fifth and sixth would be separate to, as you can see), but before testing a hypothesis that involves error stacking, check the simpler one - programming pin error.
And if you thought you didn't know how to read a schematic, I hope I managed to prove you wrong.
Gustav
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