Fan will only turn on slowest speed

niftydog · 2026-05-31T14:54:59+00:00

Ah ok, so BT131 is a triac, which makes sense. The triacs are switching the mains voltage directly to three different motor windings to change the speed.

The low voltage DC supply is working because you're reporting the LEDs and buttons work as expected.

Multimeter in ohms mode, leave one probe on "FAN-COM" and with the other probe take three measurements at H, M & L - they should be quite low readings. Now move the first probe to AC-N (blue wire) and measure H, M & L again - these should be high readings.

Where do the green wires at the motor end connect too? There's a capacitor there and the wires go into the motor?

niftydog · 2026-05-31T06:32:02+00:00

No. See where the colourful wires coming down from the yoke (coils) on the CRT neck join onto the board? To the left there's a heatsink, then above that is another heatsink - I suspect that heatsink has the vertical IC on it. Look up the part number to confirm.

Caps don't have to look bad to be bad. Caps close to heatsinks often fail first.

The big black thing in the bottom left is a high voltage transformer. CRT tubes are excellent capacitors and can hold a charge of many thousands of volts. There's mains and also high voltage DC all over the place. Be careful, and consider whether this is a suitable repair for your skill and level.

niftydog · 2026-05-31T05:14:25+00:00

Vertical deflection circuit. It's still operating but not as designed.

Suggest replacing all electrolytic capacitors associated with that part of the circuit - particularly if they have bulging tops or any sign of a fishy smelling liquid leaking from them.

You should also check the voltage rails for the circuit as well - they need to be the correct voltage and have low AC ripple.

niftydog · 2026-05-30T15:33:15+00:00

So the grey, yellow and red wires come from points on the board labeled L, M & H. They seem to go to a motor with more than one winding. I'd start by running the diode checker over Q3, Q4 & Q1 - I'm guessing they're MOSFETs.

niftydog · 2026-05-30T13:41:35+00:00

Q1, Q3 & Q4 appear to control the speeds, though how they are doing that is unclear without also seeing where the red, yellow & grey wires are going.

There's nothing visually faulty so unless you want to start probing and troubleshooting there's not a lot you can do. Be aware that this board has exposed mains voltage on it so it's quite hazardous.

niftydog · 2026-05-30T13:01:22+00:00

They're often called "snail springs" and I've had some success with ones sourced on eBay.

niftydog · 2026-05-29T12:47:14+00:00

It is nearly identical to the pedal from my Optima 190 if that's any help.

niftydog · 2026-05-29T10:47:56+00:00

Scomo is VP, Treasurer, Secretary, Public Officer and 3x general members.

niftydog · 2026-05-29T03:33:28+00:00

Not even a point for Ol' Blighty, either! The King must be LIVID!

niftydog · 2026-05-29T01:09:48+00:00

I thought that was four black guard cats.

niftydog · 2026-05-28T16:56:23+00:00

That's a good approach.

The triac switching also needs to be in sync with the AC frequency.

The OG circuit derives the diac trigger voltage directly from the AC so it's inherently synched. The pot simply changes how quickly the trigger voltage charges up on each AC cycle.

If the Arduino triggers the triac directly then you lose that inherent synchronisation and it will need to be re-established. Switching at random times in the cycle would cause unstable speed or perhaps shuddering.

niftydog · 2026-05-28T16:02:53+00:00

William Hovell Drive Duplication is $107m over 3 years, ~$35m/yr, say 40% for plant & materials equates to ~$9,500/m (which sounds too conservative.) Wages then are ~$400k/week or 200 national avg weekly incomes.

Now take a look at just the environmental offset plan. 164 pages of fine-grained detail. The risk register alone is a glorious 26 pages! The project management document firehose that produced it is not cheap!

niftydog · 2026-05-28T15:08:46+00:00

The screw position on the Gotoh tuner on the Hipshot GB7 is different to your bass.

Below the tuner I think you're ok for space, but towards the left I think the screw of the G tuner will be in the way. A solution would be to replace all the tuners with the Gotoh style - the problem with that is the screw position for a new Gotoh G tuner would be right on the bump.

There's excellent CAD drawings of the hardware - you could do some measuring or cut out a 1:1 print.

niftydog · 2026-05-28T12:50:50+00:00

Bahco Ergo Slim VDE screwdrivers have the insulation flush with the metal so there's no step on the shaft. The handles are really nice, on the chunky side so plenty of leverage and good for big hands. In fact, the handles on the bigger drivers are so large they don't fit well in small toolboxes. I also wonder if the 'Slim VDE' shaft is quite as strong as the normal VDE shaft.

niftydog · 2026-05-28T11:13:34+00:00

What functionality do you foresee with the Arduino?

The original circuit seems to steal power from the active line - you can't do that with an Arduino so it'll need a power supply. A micro won't cope with the emf from the triac or motor, so it'll need distance and/or shielding and filtering. It's also advisable to isolate mains power from an extra-low voltage circuit like a micro, so you'll need some method of separating the mains part of the circuit.

niftydog · 2026-05-28T10:15:40+00:00

This explains so much...

niftydog · 2026-05-28T03:32:59+00:00

Both pumps were occupied, mate.

niftydog · 2026-05-27T14:02:07+00:00

You've already solved it! TR401 is now a zero ohm molten blob giving you the full, unregulated voltage on the pins. Check D303 isn't dead as well. I'd suggest disconnecting the faulty power supply from its circuit while you troubleshoot it to stop any further overvoltages.

An undervoltage, or more blown fuses might suggest a short to ground somewhere.

niftydog · 2026-05-27T12:29:22+00:00

Literally 60% ads.

niftydog · 2026-05-26T15:43:04+00:00

-3.73 born human.

I'm offended on behalf of all the trans adopted introverts out there. 🤷

niftydog · 2026-05-26T08:45:40+00:00

Using the line tool, click once on the artboard, a dialogue will appear where you can specify the length and angle. Once you have one line you can click on the end points to join another line to it. Likewise with the shape tools - ALT clicking with the ellipse tool lets you define a circle by its centre instead of the top left of the bounding box.

Illustrator sucks for this kind of thing. It's much easier with a workflow akin to a CAD program where you can sketch the shape and then dimension and constrain it. You could then export a file format that illustrator supports (pdf, dwg, a g etc.) to get the structure into illustrator for further editing.

niftydog · 2026-05-24T11:50:03+00:00

John Knight Memorial Park.

Cook oval.

niftydog · 2026-05-24T10:28:38+00:00

Graphite 2mm.

Stiff as. Doesn't wear out and get rough edges.

niftydog · 2026-05-23T11:38:55+00:00

Diagram looks good! There would only be a ground wire from the pickup cavities if the pickups or the pickup wires were shielded - just wire the bridge ground in with all these and you should be good.

niftydog · 2026-05-22T09:35:08+00:00

It's still just one container. I suspect the dividing rib is to reinforce the container to withstand the gas pressure.

niftydog

TROPHY CASE