i need the oki chip M6404A-174 for the sony cdp-555esd / 705esd
Maybe someone has a spare chip like this?
Maybe someone has a spare chip like this?
Hi! What's the matter with the CD Player? What are the symptoms? If it appears to be a CPU problem, first of all, check Reset circuit.
It has aleady been reset. There are no timing signals coming from the pins of the ic
Hi. Does the cpu oscillates? I mean, the quartz oscillator generator, generates the clock signal. I've seen other times, that a bad IC, makes the cpu work anomaly. About the reset signal, usually is zero volts when you start up minus than a second for to reset, an then five volts.
Hello. I've seen the service manual. I still think that another component make malfunctioning the CPU. You must know that are some ICs that are linked to the CPU, if one of this IC doesn't work, can produce a malfunctioning in the CPU. I've seen that are some Reset signals. This Reset signals should be seen by an oscilloscope. Its 0v when you power on while a few instant, and then 5V, is only a Reset, but it is important to start the cpu running. I forgot to remain to check power supply, power regulator, fuses, and solid state fuses. Solid state fuses looks like a transistor, but it only have two legs.
Then, if the thing does not work, you can disconect all the suspect ICs linked to the CPU. I'd try everything, because a new CPU is almost impossible to get, and I'm almost sure that the CPU, if it oscillates, it works. It is not a easy failure if you don't have experience.
Then, if the thing does not work, you can disconect all the suspect ICs linked to the CPU. I'd try everything, because a new CPU is almost impossible to get, and I'm almost sure that the CPU, if it oscillates, it works. It is not a easy failure if you don't have experience.
I'm almost sure that CPU is ok, and the motive of malfunctioning is caused by another component. Maybe I'm wrong, but I'd investigate in that way the failure.
Isolate the most as possible the CPU from other parts of the circuit, and check Reset signals, power regulators and solid state fuses.
Isolate the most as possible the CPU from other parts of the circuit, and check Reset signals, power regulators and solid state fuses.