SD2000 Chips

[Altra]

chip?

Take a look at this data sheet, it is a quad 555 timer chip. "NE558"

http://noel.feld.cvut.cz/hw/philips/acrobat/5010.pdf

[Elie]

what paint? lol

[Woody.au]

Its not any of the chips mentioned so far as the supply pins do not match.

[ZED]

"""""The audio chip vco/opamp?? 16 pin dip still has me stumped except that pin 5 is Negative and pin 12 is positive pin 9 and / or 13 are inputs ... That must narrow the field down a little."""""

Hey Woody your connects may need another look,my 2000 [version 4] has pin 5 as -5v,pins 10 and 12 as inputs from tlc074[with diode across inputs].
Pins 9 and 13 are tied together .

Zed

[Woody.au]

You need to look at the suppy rails from is local supply, find the supply bypass cap and then meter out VDD and VSS and you will find that pin 5 is Negative and pin 12 is Positive in respect to the supply. Other pins have a multitude of various voltages and I cannot for the life of me find out what this chip is. It was around before 1995 and I have looked in my old National books and it aint in there. Could be a TDA chip? I wonder if Bruce would tell us?

[ZED]

Woody did ya spot the 2 traces running down the edge of the board from the tlc074 to the vco? Pins 8,9 on tlc074 to pins 10 and 12 on mystery IC.

One output of the 4053 goes to a cct that manages the tone control,another output doubles back to an opamp then on to the tlc074.

Zed

[Max]

The audio chip vco/opamp?? 16 pin dip still has me stumped except that pin 5 is Negative and pin 12 is positive pin 9 and / or 13 are inputs ... That must narrow the field down a little.

Could be something like this ?

[Qiaozhi]

You need to look at the suppy rails from is local supply, find the supply bypass cap and then meter out VDD and VSS and you will find that pin 5 is Negative and pin 12 is Positive in respect to the supply. Other pins have a multitude of various voltages and I cannot for the life of me find out what this chip is. It was around before 1995 and I have looked in my old National books and it aint in there. Could be a TDA chip? I wonder if Bruce would tell us?

Maybe it's a transistor array. At least that would explain the power pins being in a odd location.

[Woody.au]

Max, you may be onto something, I will scope the chip and see if I can make any sense of it. I cannot find many IC with pin 5 and Gnd.

[Woody.au]

This is what I found bt using the cro on the chip, the 5V pins are 5 5.5 5.8 not that it would make much difference

[bugwhiskers]

Maybe a ring modulator chip ???

[Max]

or maybe something like this...

[Qiaozhi]

or maybe something like this...

That's what I said earlier.

Maybe it's a transistor array. At least that would explain the power pins being in a odd location.

[Max]

That's what I said earlier.

Hi,
yes, could be like you said a transistor array...

He could test for junctions like in the picture... to see if the thing make sense or not.

The fact that there are so many PWM inputs and just 2 outputs could give also other wild guesses...

- some kind of "unknown" (rare) MCU /programmable device
- some kind of sound syntethizer, e.g. 2channel one pwm based like in old homecomputer or some other digital audio interface

Best regards,
Max

[Woody.au]

Pins 4, 14 and 15 are connected together, pins 9 and 13 are connected together.

Measuring for transistor junctions is difficult while the device is still soldered into the circuit board, I will unsolder him and test the device, maybe he is a transistor array.