Exciter voltage and adjustment on AEAD-200LE serial kb048669

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After a bit more tinkering it developed the idle mix was misadjusted. To make matters worse, there's
no air seal on the idle mix screw, adding indeterminate amounts of air to the idle circuit. It wasn't
hard to set up a crude seal with a greased o-ring and flat washer under the lock spring....

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It's tempting to think of the problem as overspeed at no load, rather than
underspeed at full load, given that the throttle is only moving about 1/3rd
of full travel at nearly 5kW (not 4 as I wrote earlier).

There's no hint the machine ever had a spring such as yours and I can't...

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The governor arm link on mine lacks the reverse bend to provide clearance near the spring
anchor hole in the throttle crank. I tried using a very soft B&S governor spring in a fashion
similar to your setup, but the added friction (I think) caused more trouble than it solved. The
...

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It looks as if things behave much better with both springs in their 3rd hole from the governor shaft.
With 65 Hz no-load the machine holds 60 Hz and 120 V at roughly 4 KW. I'll test more thoroughly
to make sure, but the worst problems are fixed.

There's perceptible play in...

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Replacing R70 and the zener diode seems to have brought the 15 volt supply
back. The duplex outlets are about 120 V at 62-63 Hz and sag to 116 under a
1 KW load. The frequency drops to 55-56 Hz, which seems rather a large change.
The throttle is just barely off the stop screw, so there...

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Excellent call. It looks like D51 (27 volt zener) is shorted. How that happened is
the next mystery; DC input should only be about 22 V at generate speed, zero
at weld speed. The caps aren't leaking or bulged.

Any suggestions on how to remove the conformal coating without doing...

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It looks as if this is badly wrong. On close inspection the voltage regulator board seems to have lost its
15 volt power supply. The apparent cause is the overheated R70, which lowers the input voltage to
the regulator to 10 volts. Obviously, a 7815 can't make 15 volts out of 10. No other...

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With R4 and R2 bypassed completely the
AC weld voltage is 79 VAC
100 Hz outlet is 131 VAC no load at 99.5 Hz
Exciter voltage is about 140 VAC

At 60 Hz the duplex outlets are at 120 VAC but drop to about 99-101 VAC with an 800 watt load at around 59 Hz.
The exciter...

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Seems unlikely. It's a brand new Kill-A-Watt which reads 60 Hz when plugged into the wall.

I just re-checked the brushes, the center, shortest one is 14 mm long. I've been seeing an
ohm or so between it and the rectifier positive, but the connection seemed noisy. The holder
...

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It does not seem possible to obtain rated AC exciter voltage by adjusting R4. With R4 jumpered 100 Hz exciter voltage is only
about 140 VAC at the stator leads on the fuseholder and SR2. RC4 reads 130.5, frequency is 100.1-100.4 Hz.

With R4 in its original setting the exciter shows...

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With no load applied after about ten minutes of warmup:

At the duplex outlet I see 103-104 VAC at 62 Hz. The frequency
wanders 1 or 2 Hz over the span of several seconds

At the 100 Hz outlet I see 119 VAC at 94.5 Hz, quite steady.
The Kill-A-Watt is only rated for...

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Using a Kill-A-Watt makes things much easier, thank you!

It turns out the tach was reading low, so the machine was running around 67 Hz.

I re-did the measurements with the RPM set to 62-63 Hz to start with. It drifted up to 63-64 Hz
by the time the measurements were complete....

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RPM was measured using a tachometer, unfortunately I don't have a frequency counter. I did check the brushes,
they move freely and are plenty long. Brush resistance appears to be one or two ohms. That's higher than I expected,
but small compared to the resistance of the exciter field winding....

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What is the correct exciter voltage for a 1991 Miller Legend?

I've got a machine that runs, welds and generates, but all of the open circuit voltages are a little low, for example the 240 plug
shows about 219. A 10 amp 120 volt load knocks it down to about 209 VAC. RPM is correct....

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I'd like to try setting up remote current control on a Miller AEAD-200LE serial KB048669, for use with an HF251D
serial LB087247. There have been several threads on this topic, but all some years ago with no definitive resolution.
The most encouraging post was a note from member Weldersales...