I've watched this video over and over trying to understand the build so I can fix a PT-31 I bought off Facebook Marketplace recently. I realized from your video that the PT-31 (which is thought to be a grey copy of the PT-30) is actually very different inside. I really want to fix this thing, but it won't power on, sadly. You mention that the power switch graphite transfer paper component is a likely point of failure in this model and I see it is the same in my PT-31. You said it was repairable with a graphite pen. Do you have an example of this? I live in Thailand and I'm trying to find the exact thing I need for that. I'm hoping the switch is the bad part in the circuit. I have pencils, but it sounded like you didn't fully advise going that route. What product do you recommend for this kind of thing, if you don't mind telling me? I have found that the trim pot for tuning the keyboard from the hole in the underside has been knocked loose also, but unfortunately, it's disappeared from someone's previous attempt to repair. Do you think this could be another possible point of failure? Also, have you found a service manual by chance? Sorry for all the questions. I really want to bring my PT-31 back to life. Thank you so much for the thorough video. It is very pleasant and informative with your style of filming and speaking. :)
If I remember correctly, at the time "A Keyboard" was just that, it had no in built capability for making sounds. That was provided by the synthesiser, which was separate. So perhaps the naming was to indicate that you didn't need a separate synth?
The printed “extra layer” conductors was a process that was patented way before that was built. Originally used for ceramic hybrid modules produced by AB Electronics back in the day… but adapted for PCBs.
@@a531016 sorry not sure. But it was done both with conductive carbon ink that was also used for making printed resistors and also with silver ink for tacks needing higher current or smaller dimensions. The carbon ink was also in different formulations for different purposes and could be laser trimmed for precise values after baking (better than 0.1%).
My brother had a similar model, the ones that came with interchangeable rom cards that had several songs on, it had leds above the keys which light up which notes to play so you could play along with the songs
I've got one in red as a kid. Never managed to understand how it worked, but I did push all the buttons to see what they were doing.... Time to start using it again...
the pot board is most likely used on many casio models, hence its a separate board, I'd guess. Great video, I had one of these very similar, or older even... you remind me with every video how older we get every day, thanks! ;) lol
4:06 - look carefully around the edges of the IC you can see short track under the pins that do provide the shorts. So not bad soldering. Apart from the TRHC area that looks like a post production bodge. 1/4 inc American! what are you thinking, it's ENGLISH!. We started to convert to metric only after 1965. 🙂
1965?!?! How old do I look? Since I am an engineer that has worked with energey and heat for my day job, but I couldn't tell you what a British Thermal Units means, but America still use them routinely they are welcome to inherit them! I didn't manage to find a data sheet for the IC in that package to confirm the pinout, but even though many of the joins look consistent enough, there are a few that still look suspicious to me? I would assume it worked however, otherwise it wouldn't have spent nearly 30 years in the device!
@@a531016 Younger than me ! 63 this year! I found a similar unit HD 43530 3A13 use the image search option and you will find a good example at the start. - (Sorry Utube does not like links...) This one is much cleaner and has no rework on it. It mentions a Kansas City interface, that's a very early cassette driver, 1200.2400Hz I think. Used on early computer boards, I think the Ohio Superboard, UK101 and maybe the SCMP may have used this system. The chip is a different part number, but it would not surprise me if that particular chip went through a couple of revisions. Using normal audio cassette recorders was very often a painful experience and all sorts of tweaks and bodges appeared in an effort to make them work reliably. Andy
would have loved to see Sam live and meet the UK E14 gang, plenty of you were there I've seen :) I have probably eight small keyboards of the generation before that, they also have a single chip solution in it.
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I've watched this video over and over trying to understand the build so I can fix a PT-31 I bought off Facebook Marketplace recently. I realized from your video that the PT-31 (which is thought to be a grey copy of the PT-30) is actually very different inside. I really want to fix this thing, but it won't power on, sadly.
You mention that the power switch graphite transfer paper component is a likely point of failure in this model and I see it is the same in my PT-31. You said it was repairable with a graphite pen. Do you have an example of this? I live in Thailand and I'm trying to find the exact thing I need for that. I'm hoping the switch is the bad part in the circuit. I have pencils, but it sounded like you didn't fully advise going that route. What product do you recommend for this kind of thing, if you don't mind telling me?
I have found that the trim pot for tuning the keyboard from the hole in the underside has been knocked loose also, but unfortunately, it's disappeared from someone's previous attempt to repair. Do you think this could be another possible point of failure?
Also, have you found a service manual by chance? Sorry for all the questions. I really want to bring my PT-31 back to life. Thank you so much for the thorough video. It is very pleasant and informative with your style of filming and speaking. :)
If I remember correctly, at the time "A Keyboard" was just that, it had no in built capability for making sounds. That was provided by the synthesiser, which was separate. So perhaps the naming was to indicate that you didn't need a separate synth?
Interesting!!! That would make a whole load of sense!
The printed “extra layer” conductors was a process that was patented way before that was built. Originally used for ceramic hybrid modules produced by AB Electronics back in the day… but adapted for PCBs.
Is there a particular name for this style or process that you know of?
@@a531016 sorry not sure. But it was done both with conductive carbon ink that was also used for making printed resistors and also with silver ink for tacks needing higher current or smaller dimensions. The carbon ink was also in different formulations for different purposes and could be laser trimmed for precise values after baking (better than 0.1%).
@@MarkGovier
Electronic Engineer 1: But, that can’t be done, on just a single-sided PCB …
Electronic Engineer 2: “Welcome to the Layer Cake …”
My brother had a similar model, the ones that came with interchangeable rom cards that had several songs on, it had leds above the keys which light up which notes to play so you could play along with the songs
PT-80, 82 or 87, from the sounds of it … ?
I've got one in red as a kid. Never managed to understand how it worked, but I did push all the buttons to see what they were doing.... Time to start using it again...
I like to hear how it sounds before disassemble...
Sadly, non functional... I will see if I can coax it back to life eventually!
Wow I’ve got one of these that doesn’t work but wrapped up in cling film to keep it dry. I might dig it out and see if I can fix it
the pot board is most likely used on many casio models, hence its a separate board, I'd guess. Great video, I had one of these very similar, or older even... you remind me with every video how older we get every day, thanks! ;) lol
Sorry, it's not on purpose!
thanks a lot for the neat video!
4:06 - look carefully around the edges of the IC you can see short track under the pins that do provide the shorts. So not bad soldering. Apart from the TRHC area that looks like a post production bodge.
1/4 inc American! what are you thinking, it's ENGLISH!. We started to convert to metric only after 1965. 🙂
1965?!?! How old do I look? Since I am an engineer that has worked with energey and heat for my day job, but I couldn't tell you what a British Thermal Units means, but America still use them routinely they are welcome to inherit them!
I didn't manage to find a data sheet for the IC in that package to confirm the pinout, but even though many of the joins look consistent enough, there are a few that still look suspicious to me? I would assume it worked however, otherwise it wouldn't have spent nearly 30 years in the device!
@@a531016 Younger than me ! 63 this year!
I found a similar unit HD 43530 3A13 use the image search option and you will find a good example at the start. - (Sorry Utube does not like links...) This one is much cleaner and has no rework on it. It mentions a Kansas City interface, that's a very early cassette driver, 1200.2400Hz I think.
Used on early computer boards, I think the Ohio Superboard, UK101 and maybe the SCMP may have used this system.
The chip is a different part number, but it would not surprise me if that particular chip went through a couple of revisions.
Using normal audio cassette recorders was very often a painful experience and all sorts of tweaks and bodges appeared in an effort to make them work reliably.
Andy
Is this a "Sleng Teng" keyboard?
would have loved to see Sam live and meet the UK E14 gang, plenty of you were there I've seen :) I have probably eight small keyboards of the generation before that, they also have a single chip solution in it.
You should have come, it was great!
You didn't delve deeper into the sloppy soldering. Forgot? Not an issue after all?
I didn't manage to find a data sheet for this package to find the pinout? If you manage, let us know!
@@a531016 Indeed, I couldn't even find an old service sheet for the PT-30 either.