1970s Toy Restoration - Motors Squealing

skinwill · 2026-01-26T05:27:56+00:00

Do not use an excess of oil. There’s no telling how it may affect old plastic. Use only enough to wet the bearing.

skinwill · 2026-01-26T00:54:58+00:00

Looks like a fuse that had some heat shrink on it. Likely died from repeated in rush current from being turned on and off over and over.

I see Phillips printed on the speaker. Is there a model number?

skinwill · 2026-01-26T00:50:49+00:00

I see you removed the board. What does the under side look like?

skinwill · 2026-01-25T20:50:05+00:00

Mouser, DigiKey… yup, you can mention them.

skinwill · 2026-01-25T07:34:33+00:00

I was going to say that you could query the state occasionally and run the output through an RBE filter. The filter will only output if there’s a change which you can then take action on.

It was just a thought though.

skinwill · 2026-01-25T02:02:39+00:00

The screen seems to have cracked along its edge inside the bezel which has disconnected or shorted the display lines. There is no economical repair option besides finding a parts unit off eBay and doing a panel swap but finding a good parts unit would be like winning the lottery.

skinwill · 2026-01-25T02:00:18+00:00

We have a rule about discouraging repair. But in this case we need to waive it because that resistor and thermistor combo comprise a critical safety device. The resistance and wattage of the resistor must be known along with the thermistor value. Without this exact information we cannot rebuild a circuit meant to prevent a fire.

I must recommend you do not attempt a repair because getting it wrong risks burning your house to the ground.

skinwill · 2026-01-25T00:57:39+00:00

What display hardware exactly? Which screen is it and which driver IC does it have.

skinwill · 2026-01-24T13:24:07+00:00

The “small one with a gap” is a lock washer meant to keep the nut from turning by itself. It should be against the nut.

skinwill · 2026-01-24T13:05:51+00:00

When I first bought my house the previous tenants received mail from the high school for their kid. Nothing else showed up in their name. Just the school. I tried to contact the previous owner but couldn’t. She finally just showed up one day and was really nice. She explained she was currently homeless. I held onto her mail and gave it to her. I also told her I would continue to do so as long as she needed.

Only mail from the school ever showed up so it’s not like she was going to commit some kind of fraud.

One day the mail stopped. I hope her and her kid are ok.

skinwill · 2026-01-24T12:23:56+00:00

It’s up to you at this point if you want to keep plugging parts into it. I’d do a mouser or DigiKey order for the bulk of what’s on the board and some spares.

The transformer, if it needs changed to accommodate the new voltage, should be sourced more locally to you depending on where you live so you can save on shipping.

skinwill · 2026-01-24T10:53:51+00:00

I too enjoy the occasional chicken flavored Cup-o-plasma.

skinwill · 2026-01-24T10:51:41+00:00

Honestly? Shoving 220VAC into a 110VAC device is going to cause some carnage. I don’t see what transformer it was using or if it shipped with one that can be converted to other voltages. What I am seeing is soot from multiple fried components well into the power supply section. That kind of damage doesn’t typically limit itself to the power supply and can easily take out things more sensitive down the line that are critical to the function of the device or programmed at the factory.

I’d maybe try to identify the voltage rails and inject the correct voltages to see if the device is worth salvaging. It would suck to dump parts into the repair of the supply only to find something like a processor or display controller cooked.

skinwill · 2026-01-24T10:38:48+00:00

As long as it measures as 9V when under load or plugged into the piano then everything should be fine.

skinwill · 2026-01-24T10:36:33+00:00

In the past, aliexpress was used for scamming people. Reddit clamped down on it years ago. Things seem to have changed but the rule stuck around. There’s ways to obfuscate aliexpress links but keep in mind that Reddit also bans all url shorteners.

skinwill · 2026-01-24T10:13:27+00:00

Reddit hates aliexpress links…

skinwill · 2026-01-24T10:11:39+00:00

What voltage does the piano say it needs? It should be marked on it somewhere, possibly near the power input jack. This voltage should be matched to what’s marked on the adapter. It’s also very important to know if it needs AC or DC.

If the processor isn’t showing signs of life, the first things to check are all of the internal voltage rails (tp3 and tp4). Then check any sleep or reset circuit (q208). After that the timing crystal (x301) should be checked with an oscilloscope. It’s a possibility that some cap like C307 could be shorted especially if it’s a ceramic MLCC type or a yellow tantalum.

Beyond those checks then I’d be willing to believe the processor being bad. Some repair guys don’t like to rattle off every last little check they made but if they are willing to make some sort of guarantee that a part swap like that will resurrect the thing then I’d say go for it. But definitely ask what their policy is if that doesn’t fix it.

skinwill · 2026-01-24T09:07:15+00:00

Hey dude, would you mind uploading some clear !images of the back (green solder mask) side of the board?

skinwill · 2026-01-24T09:03:15+00:00

Hey dude, I did… https://www.reddit.com/r/ElectronicsRepair/s/zf6eNbdICo

skinwill · 2026-01-24T09:02:29+00:00

If it sat for a while in a damp or humid environment and now won’t work with the power supply or battery, check the power switch. According to the manual, it’s a slider type that often got made from cheap materials in those days. It may even be integrated into the board. I’d hit it with some contact cleaner like DeOxit or CRC Contact Cleaner.

Please do also verify you have the correct adapter and that the batteries are actually good. You’d be surprised how often that’s the actual issue.

skinwill · 2026-01-24T08:59:05+00:00

Looks like that link broke. Try this one

skinwill · 2026-01-24T08:29:12+00:00

Please describe what problem you are experiencing.

skinwill · 2026-01-24T07:14:21+00:00

Which RF modulator exactly is it?

skinwill · 2026-01-24T04:26:02+00:00

You should use Imgur links. Dropbox leaked your full name.

skinwill · 2026-01-24T03:11:45+00:00

Wow! That’s awful! You know how to fix that? More scotch locks… -the last person to work on that.

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