Help! Philips CD80 dead MCU

[eboy2003]

Help! CD80 gurus. I forgot to plugin the front panel 8-pin data cable when power on the CD80. Then I made a stupid mistake, without powering off, I just hot plugin the data cable. Now I believe the MCU is dead, there is no display, and the turntable motor keeps spinning once power up. I measured the RESET pin (pin 1) of MCU (marked SC409017P P115), it's always 0V, even if I disconnect the front panel data cable and power cable.

Are there anything else I can do to troubleshoot? Does anyone know any low end CD player has the same 68HC05 MCU P115 version I can pull MCU from?

Many thanks!

[amc184]

The first thing I would do is check all of the power supply voltages. Continuous operation of the spindle motor doesn't usually indicate a uC fault, it is an indicator that something is wrong with either the decoder or spindle motor drive amplifier. In your case, I would suspect a power supply fault.

Measure the PSU voltages and post the results.

[guido]

Indeed, a reset pin is normally input. So check the reset circuit itself or it's powersupply.

Some years ago i bought a faulty cd80 with cracks in the powersupply pcb in the tracks. Also the display controller was broken, but i could still order it at a repair shop! Parts are still available, at least over here.

I don't think you can find the same 68hc05 in another player. Philips normally used their own controllers (the thing is made in the former philips plant in belgium), but not here.

[eboy2003]

Originally Posted by amc184

The first thing I would do is check all of the power supply voltages. Continuous operation of the spindle motor doesn't usually indicate a uC fault, it is an indicator that something is wrong with either the decoder or spindle motor drive amplifier. In your case, I would suspect a power supply fault.

Measure the PSU voltages and post the results.

Thanks all the advice. I purchased the CD80 service manual and measured all power supply outputs. The +19V rail is at 0V and further narrowed down to a 6V2 zener diode is dead. I don't have the replace parts right now but I will post back after the +19V analog rail is fixed.

[eboy2003]

Repaired. It's all caused by the +19V rail. There is a 1ohm resister (3512) is open. It's amazing the analog +/-15V would affect MCU startup.

[srivenkat]

Hi, I have a philips cd-80 and its always giving me "Error" while reading the CD for first 10-20 mins.. it will try reading but will make some sort of 'tik..tik.. ' noise then it works alright after 20 mins. Any ideas, what could cause this behaviour? really appreciate your help.

Thank you,
Sri

[amc184]

That 'tik - tik' noise is the laser trying (and failing) to focus. This is pretty normal behaviour for an old player of this type. Replace all of the electrolytic capacitors and it should be as good as new.

[srivenkat]

Hello amc184,

Thanks for your reply. Let me try that, reading the posts here I was thinking may be the transport gone bad. Is there a way, we can find whether the transport is bad or not?

Thanks again,
Sri

[michael_nipomo]

After the player is on for a few minutes if I change tracks or use the Random button I get the "ERROR" message. Have changed all of the electrolytics on the servo board and that made things a lot better but it is still a problem. Have also changed the bi-polar .68uf to poly at the same time that I upgraded the electrolytics on the servo boards. I have seen comments regarding grounding problems, but they were not specific as to which board or to specific components. Any recommendations would be appreciated.

[stephensank]

The remaining problem you describe is more suggestive, to me, of a need for laser current or other adjustment than anything else. Do you have access to the service manual, a dmm and an oscilloscope?