Sony ICF-C12W Radio Clock schematics (power)

[eccerr0r]

Re: Sony ICF-C12W Radio Clock schematics (power)

Chances are if it's 12V center tapped, the center tap would be 6V and way too high for the heater.

[UserXP]

Re: Sony ICF-C12W Radio Clock schematics (power)

There's a tap for the filament heater, does not appear to be center tapped however - off center tap...

So finding a suitable 220-240VAC transformer with that specific output will be next to impossible?

I found a 6-0-6 transformer which gives a total of 12V, so I hoped it would work. But it would be off-center, right? Would it work or would it over/undervolt some of the components and damage them?

[eccerr0r]

Re: Sony ICF-C12W Radio Clock schematics (power)

There's a tap for the filament heater, does not appear to be center tapped however - off center tap...

[UserXP]

Re: Sony ICF-C12W Radio Clock schematics (power)

One more question. Is the transformet in this unit a center tap one, and would it be designated as 13V, 6,5-0-6,5?

[UserXP]

Re: Sony ICF-C12W Radio Clock schematics (power)

Here it is, assembled and functional. After 40 years, it works and looks great!
Thanks, everybody, for helping me out.

When there is an 80' music hit on a local radio station played through this clock radio, it's like a time capsule.

[stj]

Re: Sony ICF-C12W Radio Clock schematics (power)

ok
it's pins 41 and 42 on the chip need to be re-wired for 24 hour mode.
41 would need to be disconnected and 42 would need to be jumpered to a different display pin.

you cant use the buttons to switch between 12 and 24 hour mode

[UserXP]

Re: Sony ICF-C12W Radio Clock schematics (power)

Yeah, I'm not sure it will go back to 60Hz power line, though.
After half an hour of testing, the clock is accurate to the second. So now it can be used.

What is strange is that C10L schematics utilize the same MSM5550RSK clock chip, and it "looked" the same but maybe there are different editions thereof. Obviously Pin12 is not a 12/24h option as per se. Shame about the 24h mode though, as it clearly worked half way. Maybe Pin18 activates it partially and there is another pin to activate the "digit 2" usage (four bits). Looking at the schematics, it's 4 bits that should light up simultaneously with the one used for the upper part of digit 1 to collectively form digit 2. They are coming from a single display pin, and that pin is connected to the chip. Looks like it should have worked, but for some reason it didn't.

[eccerr0r]

Re: Sony ICF-C12W Radio Clock schematics (power)

Ah didn't even see that other 50/60 input...

Really need to get a VFD going just to test these things. Argh, that's one of the reasons for building my grid tie inverter. Chances are, if it requires a hard line to read 50Hz, then it will run fast if plugged back into 60Hz. But only Sony or an experiment could tell...

BTW getting a USA DC-AC car inverter is another quick way to get 60Hz... with a lot of harmonics

[UserXP]

Re: Sony ICF-C12W Radio Clock schematics (power)

New update. I desoldered Pin12 from the line, left Pin18 soldered, the clock remained in a messed up 12/24 hour mode and lagging.

Resoldered Pin12, unsoldered Pin18: it returned to normal 12 hour AM/PM opeation, but the clock is then accurate!

It looks like pin12 is either a 50/60Hz selector when powered, 60Hz only when unpowered. Maybe it activates frequency auto-detection when powered - or it is a fixed state, like powered = 50Hz, unpowered = 60Hz.
Pin 18 definitiely did something to the display, but instead of activating the four fluorescent bits for digit 2, it keeps it at 1 while the second digit moves on and the symbol alternates between AM and PM.
Looks like the C12L schematics were correct to have Pin12 connected to that 11V line for that device, which is a UK version (220VAC, 50Hz). But it clearly has nothing to do with the 12/24 hour mode.

I don't mind AM/PM symbol, the clock is now accurate. What would happen if it were to be plugged in a 60Hz socket again, would it auto-detect it and run normally or run faster?
What do you make of all this?

[UserXP]

Re: Sony ICF-C12W Radio Clock schematics (power)

Pin12 should be the 12/24 hour pin according to schematics.

But pin18 has no designation, no explanation of it's supposed to do. However, on the PCB itself, the connection points between pin18 an that 11V line (as per schematics) are both circled and labeled with H (the two points I used to solder a jumper wire through).

Next to pin12 circled hole is a G letter. I connected pin12 to the same 11V line - as is Pin1.

Any ideas of what caused this weird state?
At least I hope I didn't kill the chip.

[UserXP]

Re: Sony ICF-C12W Radio Clock schematics (power)

The chip ic101 is not connected to ground, Vss (ground) of the ic is above ground by 6v. so when you measure 11vdc on pin1, that is reference to ground, so connecting pins 12 & 18 to pin 1 should be ok.
The ic uses pin14 as its ground so the ic operates at 5v, the voltage between 14 and 1

I did what you suggested and I got some weird results. The clock now seems to be running at normal speed, so I guess it switched to 50Hz counter (I'll have to do some more testing on that).

When I start it up, it no longer displays AM when blinking (it's like it's in 24H mode). When I go to set the time, the counter now goes all the way to 10, then starting 11 displays the AM symbol until it reaches 19, and then instead of switching to 20, it displays 10 and the symbol PM appears.

Now, I dodn't mind having the working AM / PM symbol displayed, but which pin has now caused the frequency to correct itself so that I can keep that one connected and detach the other one for this buggy 12/24 hour mode? Unless you have an idea how to fix the 1-10 no symbol, then 11 to 19 AM and 19 to 1 PM - and make it a normal 12/24H mode.

[stj]

Re: Sony ICF-C12W Radio Clock schematics (power)

that diagram already shows them linked together.
they are just taking the 5v from the other side of L101

[UserXP]

Re: Sony ICF-C12W Radio Clock schematics (power)

The chip ic101 is not connected to ground, Vss (ground) of the ic is above ground by 6v. so when you measure 11vdc on pin1, that is reference to ground, so connecting pins 12 & 18 to pin 1 should be ok.
The ic uses pin14 as its ground so the ic operates at 5v, the voltage between 14 and 1

Thanks so far, guys. So, R_J, do you think connecting those pins can be done like in the attached image? I used the picture from C12L schematics because its PCB is identical to the one my unit has. The pink area has available soldering pads. And Pin1 is connected to it. Will it be OK then to connect pins 12 and 18 to this long pink area because it has free pads for soldering. This part of the image already suggests that Pin12 and Pin18 are to be joined to this pink area via their respective unoccupied pads. My unit does not have those connections, it misses those two "jumper wires", if I may call them like that. I suppose a simple wire can be soldered going from each pin to this same "thick" pink area on the right. According to these schematics, the pink area is the same voltage at all areas painted in pink. And Pins 1, 12 and 18 are all pink. Would this work (of course I wouldn't want to kill the chip)? :-)

[R_J]

Re: Sony ICF-C12W Radio Clock schematics (power)

The chip ic101 is not connected to ground, Vss (ground) of the ic is above ground by 6v. so when you measure 11vdc on pin1, that is reference to ground, so connecting pins 12 & 18 to pin 1 should be ok.
The ic uses pin14 as its ground so the ic operates at 5v, the voltage between 14 and 1

[UserXP]

Re: Sony ICF-C12W Radio Clock schematics (power)

Ok, here is a noob question. Just to make sure what is the voltage on pin1, how should I test it? Set the multimeter on AC, probe pin1 and black output wire of the transformer, right?
So, if it reads ~11V, pins 12 and 18 are to be joined?

[stj]

Re: Sony ICF-C12W Radio Clock schematics (power)

just try linking 1, 12 and 18 together.
the chip is probably holding the inputs low with an internal pullup resistor so anything over a few volts will probably work.
but the power is on pin1 and you never want to feed an input with more than the supply voltage.

[UserXP]

Re: Sony ICF-C12W Radio Clock schematics (power)

I found one specimen of C12L device on eBay. It has the name "Digicube". It looks the same when it comes to controls and has exactly identical switches, but has a European plug and it says on the back that it is a 50Hz line input. So the schematics we have for that one must be representing the actual values. I can't find the one for C12W which I have. I am curious to see how the chip is powered in that C12L compared to its schematics.
The chip looks identical between C10L and C12L, yet each works on a different voltage.

[UserXP]

Re: Sony ICF-C12W Radio Clock schematics (power)

So you think that if we connect 5V to the now unconnected Pin12 and Pin18, the 12/24 hour time format will become unlocked and the chip will be able to autodetect the input frequency?

I took a second look at the schematics for C10L anf am a bit confused (sorry for not knowing much about this ), they mention two versions of the chip, one with RSK and one with 1RS suffix. The voltage on the chip in C10L seems to be 5V, whereas the voltage in the C12L schematics is 11V on those same pins.
Pin13 runs on 7V in C12L shematics, and 2.2V on C10L. Confusing. :/

[stj]

Re: Sony ICF-C12W Radio Clock schematics (power)

look at page11 the schematics i posted for the c10
pin1 should be 5v because the 11v runs though a resistor and is then clamped by a zener diode
the c10 schems label the pin functions

[UserXP]

Re: Sony ICF-C12W Radio Clock schematics (power)

Pin18 is not connected to anything, but there is also a lead going from it to a single unoccupied pad for a through-hole wire soldering (just like the one for Pin12 does). The schematics we have also do not show what that connection should be made between, as that "LW" unit also does not have a 12/24 hour mode switch (at least not a physical one, it is probably set via display).

Are you sure the chip in my unit and the one listed in the schematics are not the same? They have the same model number. Pin1 in my unit is connected to the outer D lead, which is 11V (the same one that suplies Pin13 through that R106 resistor). It gets this voltage through the contact in the function selection switch, just like the schematics show. So linking Pin12 or Pin1 would also provide it with 11V when Pin1 gets energized by the switch, wouldn't it?