Philips receiver 70FR260 does not wake up

[Gerhard]

Hi,

I am trying to repair a Philips receiver 70FR260 or FA260. It had shorted
clamp diodes and open control transistor for the power relay. I replaced
them, but still the microcontroller does not wake up.
If I pull down the micro output, the power relay turns on the set. All
supply voltages are present but the display is dead. Also removing the back
up batteries for a while didn't help.
The micro controller oscillator is running, all of its signals seem to be
ok, including the key scanning pulses. So its program is probably running.
I would appreciate suggestions to wake up this stubborn receiver!

Best regards,

Gerhard

 

[Mark D. Zacharias]

Hi,

I am trying to repair a Philips receiver 70FR260 or FA260. It had shorted
clamp diodes and open control transistor for the power relay. I replaced
them, but still the microcontroller does not wake up.
If I pull down the micro output, the power relay turns on the set. All
supply voltages are present but the display is dead. Also removing the
back up batteries for a while didn't help.
The micro controller oscillator is running, all of its signals seem to be
ok, including the key scanning pulses. So its program is probably running.
I would appreciate suggestions to wake up this stubborn receiver!

Best regards,

Gerhard

What about the reset line to the micro?

Mark Z.

 

[Gerhard]

What about the reset line to the micro?

Mark Z.

Mark,

Thanks for your response.
The /res line is high when the supply voltage is present and is pulled down
as the supply voltage drops. So I don't think the reset line is the cause.

Best regards,

Gerhard

 

[Mark D. Zacharias]

Mark,

Thanks for your response.
The /res line is high when the supply voltage is present and is pulled
down as the supply voltage drops. So I don't think the reset line is the
cause.

Best regards,

Gerhard

Had a Denon recently which looked like a bad micro - a bad PLL chip on the
tuner board was pulling down a data line. You could try unplugging some of
the peripheral boards and see if that allows the display to come up. Of
course the micro itself could be bad, you may just have to replace it to
see.


Mark Z.