How to perform an eye-pattern test on this CD player? - Page 1
Forum section: electronics / beginners

author: fubar.gr
author_rank: Unknown
timestamp: February 18, 2014, 04:58:58 pm
content: I have an old CD player that has trouble playing CDs. Luckily I found a service manual:https://www.dropbox.com/s/uy6285ikhnu03y7/philips_mcm204_ver-1.1_sm.pdfOn page 8 it describes how to perform an eye-pattern test. However, either I'm blind, or the shcematic on page 8 does not correspond to any of the schematics found towards the end of the PDF.Can anybody point out the correct probe point?

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: February 18, 2014, 06:04:29 pm
content: Check at the RF Test Point. If you see a weak blurry eye pattern, most likely the laser has degraded. You might crank up the power on the laser if it has apot, but that is only going to last a short while. Replace the laser. Cheaper to buy a new Blu-Ray player!

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: February 18, 2014, 06:11:09 pm
content: You need to use the same page # sceme that the manual does - 2 number pages .On page 5-5 I'm guessing what your looking for is CON505 in the far left - center ?

author: fubar.gr
author_rank: Unknown
timestamp: February 19, 2014, 01:48:56 pm
content: Quote from: SoundTech-LG on February 18, 2014, 06:04:29 pmThanks!I'll try it and post the waveform. Only problem is my crappy oscilloscope (DS1052e). It has persistence mode but the resolution is very low.

author: Tube_Dude
author_rank: Regular Contributor
timestamp: February 23, 2014, 02:33:49 am
content: For to see a CD player eye-pattern you must use an analog oscilloscope....

author: commongrounder
author_rank: Frequent Contributor
timestamp: February 23, 2014, 03:11:41 pm
content: Quote from: Tube_Dude on February 23, 2014, 02:33:49 amActually that isn't true these days. What is needed is the proper triggering. Dual slope triggering (X) will give you a decent eye pattern. My Fluke 199C was the first digital scope I used for eye patterns, and my Rigol DS4000 series scope does a good job as well.

author: Tube_Dude
author_rank: Regular Contributor
timestamp: February 23, 2014, 04:22:26 pm
content: Quote from: commongrounder on February 23, 2014, 03:11:41 pmBut at what pice?! ... Comparing with a good old used analog scope, that you can buy for a song...

author: Tube_Dude
author_rank: Regular Contributor
timestamp: February 23, 2014, 05:32:25 pm
content: Quote from: Dawgie on February 23, 2014, 05:01:51 pmFrom the original poster we are talking about CD player eye-pattern. That's how a CD Player eye-pattern must look like...

author: Tube_Dude
author_rank: Regular Contributor
timestamp: February 23, 2014, 07:09:45 pm
content: Quote from: Dawgie on February 23, 2014, 06:58:40 pmSo, please show a CD player eye-pattern in a digital scope.

author: commongrounder
author_rank: Frequent Contributor
timestamp: February 25, 2014, 06:18:24 pm
content: Okay. Just repaired a circa 1993 Kenwood CD player today (based on Sony laser and chipset). I grabbed some eye pattern screenshots while I was in there. This is with a Rigol DS4000 series 'scope. First one is cross slope trigger, second is positive slope, and third is negative slope. No persistence, 20Mhz bandwidth limit on. Very useable, and scope measurements are meaningful.