Micronta Talking Alarm Clock Full Recap

[jayjr1105]

My grandfather had this Micronta VoxClock3 digital alarm clock that just had random digits displayed when you plugged it in and just overall acted crazy. Opened her up last night and found every single cap either completely open or ESR in the 50 ohm range. All caps replaced but waiting on a .47uf 50v cap to arrive as I didn't have any.

[stj]

Re: Micronta Talking Alarm Clock Full Recap

.47? use a polyester cap - 470n

[jayjr1105]

Re: Micronta Talking Alarm Clock Full Recap

.47? use a polyester cap - 470n

I don't have any of those lying around either. Need to invest in a polyester assortment.

[stj]

Re: Micronta Talking Alarm Clock Full Recap

well even 1uf electrolytic caps are being phased out because film caps are small enough to replace them.

what chips are in that clock?
spo250? spo256? texas tms5110??

[jayjr1105]

Re: Micronta Talking Alarm Clock Full Recap

well even 1uf electrolytic caps are being phased out because film caps are small enough to replace them.

what chips are in that clock?
spo250? spo256? texas tms5110??

My pic is out of focus, I'll check soon

[jayjr1105]

Re: Micronta Talking Alarm Clock Full Recap

well even 1uf electrolytic caps are being phased out because film caps are small enough to replace them.

what chips are in that clock?
spo250? spo256? texas tms5110??

Here you go. Probably late 80's early 90's by the date codes on chips.

[redwire]

Re: Micronta Talking Alarm Clock Full Recap

It came out in 1986? https://www.radioshackcatalogs.com

[stj]

Re: Micronta Talking Alarm Clock Full Recap

nice, i wonder if the sample rom has been dumped!

[redwire]

Re: Micronta Talking Alarm Clock Full Recap

TMS5110 speech synthesizer was in TI Speak & Spell, it used LPC linear-predictive coding. I think it had better speech quality than SPO256 allophones.

It looks like it could use a 1-bit or 4-bit databus to read ROMs. One IC must be the main MCU and another ROM.

TMS5110AN2L-1
MP1343
CM72010NL

[stj]

Re: Micronta Talking Alarm Clock Full Recap

it uses a custom databus for the roms - there are replacement projects online.

[jayjr1105]

Re: Micronta Talking Alarm Clock Full Recap

Got the new .47 cap today and installed. Powered up without the daughter board even being re-soldered back in and it's working great! good crisp digits, no funny business. I'll post later on once I have it fully back together.

[jayjr1105]

Re: Micronta Talking Alarm Clock Full Recap

All done, working great.

[ChaosLegionnaire]

Re: Micronta Talking Alarm Clock Full Recap

good fix! yet another happy old folk! this past year has been bad for them. good to fix their stuff for them and make them happy again! thats if u are fixing it for them to return it to them and not if u get to keep it if u fix it...

[stj]

Re: Micronta Talking Alarm Clock Full Recap

i like the colour, that's done using red leds behind a purple filter isnt it?

[redwire]

Re: Micronta Talking Alarm Clock Full Recap

I need a video or sound snip to hear what it sounds like

In the 80's many red LED displays were behind a purple filter. I think it works much better for contrast (compared to red).

edit: youtube versions are crap https://www.youtube.com/results?search_query=voxclock

[ClockChip]

Re: Micronta Talking Alarm Clock Full Recap

My grandfather had this Micronta VoxClock3 digital alarm clock that just had random digits displayed when you plugged it in and just overall acted crazy. Opened her up last night and found every single cap either completely open or ESR in the 50 ohm range.

Am I right in thinking that failing caps is a relatively rare phenomenon with this particular clock? O, rather, is this a widely-known problem with the VC 3 and most owners simply choose to bin their clock rather than taking the time and trouble to repair it?

(I ask because I was quite surprised to find a mere single mention of this nearly forty-year-old clock on the forum. Perhaps my sense of surprise is misplaced?)

[eccerr0r]

Re: Micronta Talking Alarm Clock Full Recap

Capacitors have limited lifetime and people tend to throw away clocks after they...get their cell phones?

[jayjr1105]

Re: Micronta Talking Alarm Clock Full Recap

I have this clock back in my possession. My grandfather claims it still acts weird after some time. I'll take it apart and give it a closer inspection for cracked solder joints.

[stj]

Re: Micronta Talking Alarm Clock Full Recap

not enough info,
you should have asked if he meant the display or the speech

[ClockChip]

Re: Micronta Talking Alarm Clock Full Recap

I have this clock back in my possession. My grandfather claims it still acts weird after some time.

Can you please ask your grandfather whether the clock kept accurate time until recently?

I ask because, rather than using the 60 Hertz mains to maintain accuracy, this particular clock relies on the MCU frequency; I am not clear on why the manufacturer would do this (perhaps someone here knows?). However, I am informed this is not an accurate way to keep the clock synced when using the simple RC oscillator the clock was designed with.

(I know of no one else who owns one of these, so I hope you will not mind my asking.)