Hi.
While having a MEDELI M1 musical keyboard stripped down, I decided out of technical curiosity and self-teaching of how a MIDI keyboard works, to attempt to trace the MIDI part of the circuit.
Besides that, I am also tracing the (faulty) power supply, and the amplifier section.
Wondering which IC controls the MIDI data, as it has multiple voices, rhythms, MIDI record and playback, as well as MIDI-out to the DIN port.
The only 2 IC's are on the main board, silk-screening on IC typed below.
When I Googled data spec-sheets on these IC's, found that these are amplifiers.
MC4558 = op-amp and TA822PL = 2.5W dual power amp.
So I scratch my head, thinking "where the heck is the ROM or EEPROM for wavetable and MIDI?"
Going onto MEDELI's HK website, they apparently manufacture their own keyboards, and some IC's, or have them custom-made by UTC, which is obviously the case here.
So, as these are the only two chips on the entire keyboard, could one of these be the ROM or MIDI controller, perhaps by coincidence having the same part number after the UTC S*A*?
On UTC's website, (where they list these as amps), the bottom 2 characters are date codes, but the SLA2 and SKA prefixes are not listed by them.
PS- The Kyb owner reversed his 12VDC polarity after damaging & re-joining the wall-wart cable, blowing the 2.2mF 25V cap and 1N4001 diode.
Circuit still works on "battery" 9V DC power, tested with my DC supply.
Still tracing circuit...
One of my reasons for trying to source the actual MIDI IC is to pair it correctly in Frooty Loops Studio 20 (Controller Device is .......) .. eg Yamaha XYZ.
Otherwise 'New USB Audio Device' is the generic / default.
medeli m1:
C10 = 2200 u 25V ESR 1" x 0.5" (open cct)
D1 = 1N4001 silicon (open cct)
U2 = DIP-8 package.
UTC SLA2
MC4558L
YA
U5 = DIP-12H package.
UTC SKA.
TA8227PL
JD
While having a MEDELI M1 musical keyboard stripped down, I decided out of technical curiosity and self-teaching of how a MIDI keyboard works, to attempt to trace the MIDI part of the circuit.
Besides that, I am also tracing the (faulty) power supply, and the amplifier section.
Wondering which IC controls the MIDI data, as it has multiple voices, rhythms, MIDI record and playback, as well as MIDI-out to the DIN port.
The only 2 IC's are on the main board, silk-screening on IC typed below.
When I Googled data spec-sheets on these IC's, found that these are amplifiers.
MC4558 = op-amp and TA822PL = 2.5W dual power amp.
So I scratch my head, thinking "where the heck is the ROM or EEPROM for wavetable and MIDI?"
Going onto MEDELI's HK website, they apparently manufacture their own keyboards, and some IC's, or have them custom-made by UTC, which is obviously the case here.
So, as these are the only two chips on the entire keyboard, could one of these be the ROM or MIDI controller, perhaps by coincidence having the same part number after the UTC S*A*?
On UTC's website, (where they list these as amps), the bottom 2 characters are date codes, but the SLA2 and SKA prefixes are not listed by them.
PS- The Kyb owner reversed his 12VDC polarity after damaging & re-joining the wall-wart cable, blowing the 2.2mF 25V cap and 1N4001 diode.
Circuit still works on "battery" 9V DC power, tested with my DC supply.
Still tracing circuit...
One of my reasons for trying to source the actual MIDI IC is to pair it correctly in Frooty Loops Studio 20 (Controller Device is .......) .. eg Yamaha XYZ.
Otherwise 'New USB Audio Device' is the generic / default.
medeli m1:
C10 = 2200 u 25V ESR 1" x 0.5" (open cct)
D1 = 1N4001 silicon (open cct)
U2 = DIP-8 package.
UTC SLA2
MC4558L
YA
U5 = DIP-12H package.
UTC SKA.
TA8227PL
JD
