ML-TS2 MITSUBISHI MSX2 PICTURES

By wernerkai

Champion (357)

18-04-2014, 17:17

Finally, for your delight:

Pictures of MSX2 Mitsubishi ML-TS2

It has a S1985...

Some findings about the Power Supply connector:

1 - The black wire is connected to Ground... pins 7,8 of TTL chips.

2 - The Yellow wire is connected to the IN pin of that IC mounted in a heatsink. It is an SI-3052V, DC voltage regulator for 5V 2A. Max Input is 25VDC.

3 - The Orange wire is connected to the cathode of D1 and anode of D2... I guess they are half wave rectifiers. The capacitors C8 and C11 are rated for 35V. Till now, I couldn't find the +12V and -12V regulators...

So, this shows that the pinout type (GND/ACV/DCV) of power supply is compatible with Sony HB-AC3 and Panasonic FS-AA51.

But here the mains voltage is 127VAC... I must use the 127V/100V transformer.

These 18VAC PS will give a peak of 25,45VDC... This way I will search for that regulators a bit more in the PCB before trying to conduct a power-on test.

A cause for concern are that batteries. The blue one is a GB50H-2 2.4V 50mAH NiCd Battery. The white one is a CR2032 3V...

By wernerkai

Champion (357)

18-04-2014, 19:07

Hum... pin 50 (-12VDC) of the CA-CON is connected to anode of D1... And pin 48 (+12VDC) is connected to cathode of D2.

So... if 18VAC of the PS is peak-to-peak, then the peak AC voltage will be 9VAC... The max DC voltage will be 12,73 VDC... less the drop in diode... maybe 12,1 or 12,2 V.

It makes sense...

Another detail... the "Slot Doubler" is missing... Will a regular MSX cartridge work in that single slot ? Probably yes...

Slot Doubler mounted

Slot Doubler alone

By wernerkai

Champion (357)

18-04-2014, 19:45

No way... the AC output of the PS is 18VAC RMS... It seems the original Mitsubishi PS should give the half, or 9VAC RMS.

There is nothing connected to the +12VDC line, just the resistor R2 (10k) as load.

But to the -12VDC line there is the input of PL4: 79L005P, a 3-terminal negative VR. Its maximum input is -35VDC. The output is connected to IC11A which is upC4741C. I guess is the modem part of the circuit.

So, I think it won't burn... but you will have +24VDC and -24VDC instead +12VDC and -12VDC, if you use Sony or Panasonic PS...

By sd_snatcher

Prophet (3400)

18-04-2014, 20:43

Quote:

No way... the AC output of the PS is 18VAC RMS... It seems the original Mitsubishi PS should give the half, or 9VAC RMS.

Maybe it had a diode somewhere? Then it would turn into 9VDC.

Quote:

Another detail... the "Slot Doubler" is missing... Will a regular MSX cartridge work in that single slot ? Probably yes...

The MSX Magazine 1991/03 issue, pg67, describes how this slot doubler works. It uses the reserved pin-16 to route the SLTSL signal for the 2nd slot.

Let's say that you can use existing cartridges in the rear slot without trouble. They will just ignore the extra signal.

By wernerkai

Champion (357)

18-04-2014, 21:14

sd_snatcher wrote:

Maybe it had a diode somewhere? Then it would turn into 9VDC.

Yes, with a bunch of diodes... I could drop the voltage, but I could also:

1 - Build, or buy, a small 2:1 transformer...

2 - Add a small PCB with 7812 and 7912 regulators, and connect then to the MSX PCB.

3 - Use a small ready-made power supply transformer in this b) configuration, to put 18VAC in one side and to get 9VAC in the CT..

I will try option 3 first...

Thank you for the info about the Slot doubler.

By msxholder

Champion (361)

19-04-2014, 10:08

The power supply
left 8,5 V ,top 8 V, right ground
seen towards connector

By wernerkai

Champion (357)

21-04-2014, 22:02

Hello folks !!!

Thank you msxholder for the information about PS voltage.

Last saturday in the MSX Leme 2014 meeting, I've talked with fractal2000 and he told me he has the original Mitsubishi power supply, though I don't recall having seen that ML-TS2H powered on in that meeting at Jau.

I conducted the first tests with my unit, but unfortunately the computer did not work. LED on but only black screen.

I removed the batteries from the board and noticed that there was corrosion.

The matsushita CR2032 is still giving 3VDC...

After cleaning the PCB, I've tested the tracks with the multimeter and found two discontinued.

I restored the tracks and managed to make the computer work again, but I cut the orange wire and left only the +5V line.

An Alert or warning should be issued for this model and others which have batteries inside...

More pictures added here

By Manuel

Ascended (17265)

22-04-2014, 16:36

Cool! Can you run the usual dump/analyze programs on it?

By wernerkai

Champion (357)

28-04-2014, 02:58

msxholder wrote:

The power supply
left 8,5 V ,top 8 V, right ground
seen towards connector

By the way, please do you have the name/code of the Misubishi AC adaptor ? Thanks.

By sd_snatcher

Prophet (3400)

28-04-2014, 03:55

wernerkai wrote:

Yes, with a bunch of diodes... I could drop the voltage, but I could also:

No, no. What I meant was that 18VAC turns into 9VDC when passed through a diode.

Quote:

Thank you for the info about the Slot doubler.

You're welcome!

By wernerkai

Champion (357)

28-04-2014, 04:41

sd_snatcher wrote:

No, no. What I meant was that 18VAC turns into 9VDC when passed through a diode.

If it were 18VAC peak-to-peak, then half wave should be 9VAC peak. Thus, after passing through a half-wave rectifier it would give us 9 * SQRT(2) or 12,73VDC, minus the 0,5V voltage drop on silicon diode, results 12,23 VDC.

But the voltage is 18VAC RMS, what means is 36VAC peak-to-peak. Thus, the DC peak voltage is 18 * SQRT(2) = 25,25V.

User Msxholder told the original PS is 8,5VAC, thus giving 8,5*sqrt(2) = 12,02V peak. Usuallly the voltages are a bit higher, so after the diode drop it will end around 12VDC.

Regards,

Werner