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Repair a glitchy Texas Instruments Speak & Spell Speak & Read Speak & Math - capacitor issue
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- Опубликовано: 12 мар 2024
- The Texas Instrument Speak & Spell, Read, Math devices from the 80s are built like tanks and last forever if you take care of them, but sometimes they can become glitchy and unstable even when not modified/circuit bent. I often look for such devices that are listed on eBay for cheap because the seller realizes they don’t work or don’t work right. Here I show how to fix this issue by replacing one or more of the capacitors on the power board.
The relevant capacitor types/values are discussed in the video and listed here for reference (in order of suggested replacement).
NOTE: I have no affiliation or benefit whatsoever from these sellers; including links just for convenience. If links end up broken, try searching Amazon or eBay for the specifications shown. Please don't pay more than a few bucks for a single component, though sometimes you can only find them in multiples of 10. They are usually very reasonably priced.
1. 6.8 uf, 16 v Tantalum capacitor (uf means microfarad, so 6.8 microfarads. v means volts, so 16 volts rated capacity) This type of capacitor is typically teardrop-shaped and blue in color (but not always blue). Be very mindful of its polarity, it has a plus and minus side and must be inserted as shown on the circuit board. www.amazon.com...
2. 0.1 uf radial ceramic - replaces the original larger disk-shaped capacitor labeled "104". It has no polarity so it doesn't matter which lead goes where, as long as it goes in the two holes originally used of course. aretronics.com...
3. 47 uf 25v electrolytic capacitor - this one is cylindrical 'can' shaped. Again be mindful of polarity. www.amazon.com...
4. .0022 uf 50 v smaller disk-shaped capacitor (this one is rarely a problem, I'd do this last if nothing else has helped). No polarity so it doesn't matter which way it is inserted. www.amazon.com...
#circuitbent #fastmatt
Great video Matt. I have seen my fair share of electrolytic caps blow. If you get some pictures and caliper measurements for the battery doors, I would love to prototype some solutions.
I’ll bring one when we meet up with the team soon. Thanks!!
AT 11:06, do you have the model. I blew that one and haven't figured out what it was so am glad I found your channel.
If you may have damaged it with an incorrect external power supply then that’s probably not what is bad in your case - you most likely popped just the transistors. But that cylindrical cap is a 47uf 25v electrolytic capacitor.
I’ve 2 ‘non-working” and this might just be what’s wrong with them..🤔
If they don’t power on at all, I have a video for troubleshooting that. ruclips.net/video/VTOCkg3qLig/видео.html
My S&R won't switch on after many years of working great. Can you recommend troubleshooting tips? I have a voltmeter. Also, while trying to get to the underside of the circuit board I accidentally disconnected the ribbon for the keypad: does that just slide back into the connector or have I done some permanent harm? The power circuit is labeled PCU-312A. Thanks, hoping I can bring it back!
Hi @bencolemanart, for the ribbon cable it is a bit fiddly but definitely possible to get it back up in there. The later models had a more firm material at the end of the ribbon, if you are lucky you’ll have that and it’s a bit easier. If not - it takes some more patience. I probably should make a short video on how to do it. The idea is you need to get one end of it started into the connector, I use a small jewelers screwdriver (flat blade) but never force it to where you tear thru the ribbon. Just barely press it in at one end to get it up in there. and then with an index finger and thumb, firmly support the ribbon cable and gently work it into the connecter further in from that end you started to the other end. Hope that makes sense.
I will share some more troubleshooting tips here in a few hours, I have some tricks for diagnosing power issues.
@@fastmatt_circuit_bent Hi Matt, thanks for the reply! Sadly, I don't have the later model, it's going to be a nuisance, but I feel more confident doing it with your advice. Jewelers screwdriver at the ready!
@@bencolemanart I just uploaded the troubleshooting video and included tips on the ribbon cable. 🤓
My S&S was working fine when I put it in storage maybe 3 years ago . Now it gets stuck in what appears like a glitch or a boot loop , displays SPELL A but gets no further , emits a clicking noise and is otherwise unresponsive.
Is this an issue you’ve seen before ? Thanks 🙏
This does sound like the capacitors may need replacing. Any chance you could post a video with sound? If I hear it then sometimes it helps me better guess what is up with them.
I did once have a unit develop a permanent freeze loop, it sounded exactly like one of the bends I use but couldn’t be freed from it even after de-soldering all my wires. I ended up having to scrap that board and swap in a replacement for my customer. It’s rare but I have seen that at least once. Caps would always be my first thought though especially it acts a little more randomly / unstable.
@@fastmatt_circuit_bentgah, haven’t got around to this yet, but I’m 99% sure it’s the PSU. Strangely I can’t find a schematic showing the values of the caps on the PSU - is there any way you could share that please ? I’m sure I can fix them myself with this information. Thank you in advance 🙏🙏🙏
It’s so frustrating- I’m loathe to throw it away or sell it as junk when the problem is likely a component that costs Pennies!
And nobody wants the new speak and spell! Someone forgot to keep the mojo, obviously not produced by geeks and those with passion!
@sprialingprism I don't have a schematic of the board but I do discuss the capacitor values and locations in the video above. I can do one better and list those values in the video description for easier reference. I'll do that now. (edit: DONE, see video description)
@@fastmatt_circuit_bentwow I really really appreciate that -
thank you so much !
I will report back 👍👍👍