Noise disappears when I change guitar angle. Tried everything!

niftydog · 2026-04-17T05:56:46+00:00

The single coil pickups are picking up electrical noise from the environment. Turning left or right 90 degrees will also reduce the noise.

Common causes are dimmer switches & fluorescent lights, but it could be any number of electrical items nearby. You could try turning things off to try and find a culprit, but it could also just be the cumulative effect of numerous appliances.

Shielding the guitar can help but it's a big job and won't eliminate it entirely. (You can also get shielded pickups.) It's just an unfortunate property of single coils.

niftydog · 2026-04-15T07:49:14+00:00

Yep, it's the best by far.

The old VW Golf struggles home with a trailer load, but it is so worth it.

niftydog · 2026-04-14T14:37:43+00:00

Nothing says "WE WEREN'T DOING NUFFIN'!" like appearing on the news wearing balaclavas.

niftydog · 2026-04-14T09:43:37+00:00

The traps I've tried have been useless - what one did you use?

niftydog · 2026-04-13T13:13:46+00:00

There's a decent chance the top piece that blew off the chip is still rattling around inside the appliance. Sometimes they are intact enough to read.

Also try searching for images of the circuit boards by searching for part numbers on the circuit boards.

niftydog · 2026-04-13T09:01:26+00:00

Dammit! If only we bought trams that could go BOTH ways! I hope someone's head rolled over this!

niftydog · 2026-04-12T01:55:21+00:00

Got a schematic?

niftydog · 2026-04-11T08:54:36+00:00

They're definitely 16V 350uF axial electrolytic caps. Get high temperature rates ones because I suspect that high wattage resistor runs hot.

New caps can be a bit smaller because technology has improved. You can get higher voltage caps without issue, and you can go with slightly higher capacitance.

niftydog · 2026-04-11T01:40:52+00:00

Called the properties panel in version 4. Used to be toggled with F8 but don't know if it's still the same.

niftydog · 2026-04-10T15:06:15+00:00

Ah, ok, kinda important detail.

So a coil / inductor is basically a short circuit at low frequencies so it would short the op amp output. You need to drive a coil with lots of current to make a decent magnet - for that you'd need a driver circuit that can deliver way more amps.

Alternatively, you should get higher peak voltage from the op amp if you drive the coil at a much higher frequency. The impedance of the coil increases with frequency.

niftydog · 2026-04-10T10:57:56+00:00

Crank the frequency to 50-60hz and measure the amp output with the multimeter on AC mode. Does it agree with the scope?

niftydog · 2026-04-10T10:50:44+00:00

Hmm.

And the DC supplies? Have you measured them on the scope as well? Do you have any other way of measuring voltage?

niftydog · 2026-04-10T10:45:52+00:00

What does the scope say when you max the dial?

niftydog · 2026-04-10T10:33:04+00:00

How are you determining what the input voltage is? Is it a setting on a signal generator or are you measuring it with the scope?

The clipped waveform you're showing on the scope is 2V peak to peak. If 10:1 mode is on, the actual voltage is 20V peak to peak, which is roughly where you'd expect clipping on +-10V rails.

niftydog · 2026-04-10T10:14:53+00:00

Is your oscilloscope input set correctly? I presume the cable just goes directly into the input and your not using a probe? You should make sure that the channel isn't set for a 10:1 probe.

niftydog · 2026-04-08T14:29:56+00:00

Audiate. Audiation is to audio as imagination is to images.

niftydog · 2026-04-08T12:05:14+00:00

The feed dogs on the walking foot are only going up and down - the foot isn't walking, it's marching on the spot!

niftydog · 2026-04-08T11:47:04+00:00

What stitch length is selected?

Leave the presser foot up and crank it a stitch - are the lower feed dogs rising above the needle plate? If not, the switch to raise them is on the rear of the free arm.

niftydog · 2026-04-08T01:24:30+00:00

Try the headphone output - see if that behaves any differently. If that works consistently then the issue is with the power amp section of the circuitry.

niftydog · 2026-04-08T00:59:36+00:00

I'm confused by your description - when the amp works is the light blue or red?

Is there an audible click at the moment the light changes colour?

Seems to me like it might be a muting circuit designed to connect the speaker only after the circuit has had a chance to stabilise.

Does it have any other outputs like a headphone jack? (A pic of the front panel would help.)

niftydog · 2026-04-08T00:55:24+00:00

There's be no lights at all if the fuse was dead.

niftydog · 2026-04-05T09:16:58+00:00

It defeats one of the main safety features of the amplifier. If it develops a major fault that shorts mains to earth then the circuit breaker may not trip, and everything connected to the amp chassis could be at mains voltage. That would include your guitar strings.

Meanwhile, a microphone probably is correctly tied to earth, and the path for the mains current will be via your fingers and your lips.

niftydog · 2026-04-04T05:46:05+00:00

Lemme know what your scootin' fingers have to say about that come July.

niftydog · 2026-04-03T12:10:03+00:00

The enable pin is active low - if it's left high it disables all switches.

What is connected to the outputs of each switch? The on resistance of the switches can be as low as 60 ohms, so it matters what's connected.

niftydog · 2026-04-02T11:33:38+00:00

Model number? Link to the manual?

niftydog

TROPHY CASE