failure mode of child sound generator toy?

Hi All We have one of those cheap battery powered novelty sound generator toys

- 16 rubber keys, each of which when pressed plays a short 'amusing' sound clip. The Granddaughter like her 'spooky' themed one, but there are other styles available.

After a fair bit of use the sound appeared to give out, and so I replaced the batteries - 3 off LR44. I used some cheap but not super-cheap replacements form eBay (the originals are unlikely to be of high quality!). However I am still getting no proper playback, just a short 'phht' noise as each key is pressed.

I've taken a look inside and there are no eg. Electolytic capacitors to fail, so I'm wondering what the failure mode might be:

- replacements batteries too shoddy?

- flash memory inside the sealed CPU failed?

- some PSU components I am missing?

Thanks for any thoughts - it's not a big deal but we had a similar failure in a new unit a while back and I would like to know what occurs.

Cheers J^n

Reply to
jkn
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Failure of the contacts in/under the rubber keys?

Reply to
Chris Hogg

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Somebody stamping on it after being driven to distraction by the noise? :-)

Reply to
Clive George

Try a different set of LR44 batteries. You can get them from Poundland and I have found them ok. I have no idea if they last as long as branded versions, but at the price they are fine.

Also check the battery contacts in the toy to make sure they are clean.

Reply to
Jeff Layman

Because it's cheap, one guess is that there's a piezo sounder driven from a transistor which needs a pull-up resistor and this resistor or its connection has failed. This could explain the brief noise.

But it's a long shot.

Cheers

Reply to
Syd Rumpo

+1 on change batteries,cheap LR44/AG13 seem to be about a 30% duff out box ratio unless spend big money on invidually packed.

Meter might read ok but droops under load.

Reply to
Adam Aglionby

That would point to dead batteries, off load they just maintain a smidgin of energy which is enough to start the electronics but that immediately causes the voltage to collapse and everything goes off.

Reply to
Peter Parry

With 16 keys (4 x 4 matrix?) I'd not expect them all to be duff. Row/column of 4 keys maybe.

I'd go for bad batteries and/or battery contacts, remembering those contacts between the cells of the stack.

Reply to
Dave Liquorice

Mostly the membrane keyboard, but from what you say it sounds like the digital bit is knackered. The amp bit is still working hence the noise. Its probably just a sealed custom chip, and if all that happened was dead batteries, are you able to operate it from the mains via a psu? If its duff batteries then this should prove it. Brian

Reply to
Brian Gaff

Also of course make sure they are the right way around. Not always obvious in el cheapo plastic toys. I think they assume by the time the toy has dead batteries child or parent will have submerged it in water to see what happens. Brian

Reply to
Brian Gaff

+1

I've had to clean the surfaces of the cells as well, depending how they've been stored they could be tarnished. Only really an issue when the cells have to be "stacked" as they are invariably smooth with nothing to "punch through" to make the connection. I notice some "better" cells have a dimpled negative pole, whether that helps I don't know...

Reply to
Lee

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