adapter Confusion about AC adapters for 80s Casio keyboards

[aroot]

Looking for insight on AC adapters for 80s Casio keyboards, specifically AD-5 adapters.

 

I have a Casiotone CT-605 and CT-310. The power ratings on the back panels of each are the following:

DC 9V, 9.2W for the CT-605.

DC 9V, 8.5W for the CT-310. 

No explicit rating is given for the input current.

 

The AC adapter for both (and many others) is the Casio AD-5. I'm assuming that the adapters vary in name based on the region they're used. For instance AD-5U (USA), AD-5UL, AD-5J (Japan), AD-5E, AD-5EL, and so on. They all seem to output 9V, 850mA. 

 

Am I correct in assuming that the above keyboards require currents of 9.2W/9V = ~1022mA and 8.5W/9 = ~944mA? If so, why do the AD-5 adapters output a lower current than the devices they're supposed to power? What am I missing here?  

 

I have a non OEM adapter whose specs for output match the AD-5 adapter (9V, 850mA). Both of the keyboards turn on and seem to function completely fine with it, but I don't want to risk any long term damage, if any is possible. 

 

Thanks!

 

Edited February 2, 2022 by aroot
clarification

[pianokeyjoe]

While I did not wonder that at the time I messed around looking for working adapters for  my SAME model keyboards, I can say that in JAPAN the input voltage is 100/110V and NOT 125-127V as in the USA/Latin America. So you have to take that into consideration too. Now as an adult, owning these models and more, I realized the reasons why the light on the keyboards would pulse with the rhythms. Lack of power.. As a kid it was fun to see and hear, as an adult, not so much. I have been buying and using 9VDC 1A or higher adapters and having to cut the tip to reverse the polarity since there where no such thing as 9VDC 1A or higher CASIO adapters for the classic keyboards. Another option has been to use 10VDC sega and sony adapters which have higher amps too. As of NOW while designing and building my studio, I bought a 9VDC 11A industrial power supply and will install outlets in the wall that will only be used for 9VDC keyboards. No more wall warts. Direct 9VDC power from the wall but the sockets will be from another Country so as to not confuse things. But for those that cannot or do not customize their power supplies for their keyboards, I suggest find a third party 9VDC 1A or higher PSU usually from SONY or SEGA or some other device, and nip the tip, and either wire it directly to the keyboard, or if the tip fits the hole nice and snug and reliably, the reverse the polarity and tape the wires. The old fashioned way of solving that Casio polarity issue. KORG and ROLAND also use 9VDC 2A PSUs at the SAME negative tip polarity of CASIO!! Try those! Sadly, the CASIO branded adapters from the 80s, where mainly targeted at the MINI keyboards and midsized keyboards and NOT so much the full sized keyboards. Also remember that it was only the mini and midsized keyboards that came with CASIO branded dry cell batteries while the CT series, did NOT. At least I never saw that. So the AD5 is for MT series keyboards from 1986-89. The MT series from 85 back to 80 were 7.5VDC NOT 9VDC!! I could be wrong with some of this though as I am only speaking of my experiences within my local area and local availability of such instruments and adapters at the time.. IN PUERTO RICO and MAINLAND USA..

[aroot]

Hey, thanks for the quick reply. As per your recommendation, I looked around and found a few adapters over 1A, but I will most likely reverse the polarity on some 9VDC positive center adapters -- they're easier to come by. It is strange that Casio didn't come out with a more appropriate adapter for the CT series. I'd like to think there's some piece of missing information here, but it doesn't seem likely.   

 

Anyway, thanks for the useful information! I'll have to look into setting up a beefier power supply, should I buy more keyboards. 

 

 

[CYBERYOGI =CO=Windler]

Traditionally Casio used negative center power supplies, so many 1980th Casio keyboards got killed by plugging a wrong polarity (positive center) Yamaha or AC PSU in. (This happened very often on shopping center demo stands.) Only after Casio made fully digital PCM keyboards, they added a protection diode to prevent damage.

 

To make it worse, my much newer Casio SA-76 now has a positive center PSU (i.e. compatible with Yamaha) and so won't work with classic Casio adapters.

 

Most generic wall wart power supplies have a switch or reversible plug (the end at the PSU) to select polarity and voltage. Ampere rating of a PSU needs to be same or higher than the device to be powered. Voltage should be the same (slightly lower may work in devices needing >5V). Most home keyboards only draw full current at maximum volume, thus at ambient volume typical 2A keyboards may work well with 1A or less. But better avoid this with modern keyboards containing writable flash memory (XW series etc.), which may crash when voltage drops too low during write access (in worst case committing suicide by overwriting its firmware).

 

Be careful with old unregulated PSU (heavy by their iron transformer). They output higher voltage than rated (e.g. 18V instead of 12V) when the device draws less than the rated current, so set them at lower voltage. I e.g. set them to 6V instead of 9V or 7.5V instead of 12V with 1980/90th Casio keyboards.

Edited February 5, 2022 by CYBERYOGI =CO=Windler