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Sony CDP-7F troubleshooting


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#1 docs

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Posted 11 March 2019 - 02:33 PM

I found a non working Sony CDP-7F which would not turn on, I managed to find the faulty burnt out resistor and replaced it and the unit turned on afterwards  :thumbsup:

 

The issue now is that if I wait for the TOC to be read, which it does successfully initially then after a few seconds the display shows a zero and when I select a track with the track selection button and press play nothing happens (the sled motor does not move and CD does not begin spinning) and it goes back to showing a zero and then will not accept any input at all.

 

However, I have learnt that if I press play immediately on powering it on, it will play the CD, goto next/previous track no problem at all!

 

I have cleaned the lense to no avail.

 

This is not ideal so I'd like to try get to the bottom of this if anyone can help. I have the service manual already but not sure where to start!



#2 hopey

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Posted 18 March 2019 - 05:43 PM

sounds like the pickup is on its way out. I would disconect all wiring looms and reconnect then apply lubrication on all moving parts of the pickup assembley.



#3 Jorge

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Posted 19 March 2019 - 08:10 PM

+1 to what @hopey said! 

I had similar symptoms when power supplies were going bad: enough power on start-up, but then old'n'busted electrolytic would raise its ugly head. Check for a bad cap in the power supply when doing full disassembly. Never hurts to ask Kaosun (at kaosuncd.com): I have just a few dozen successful Discman projects (with D-90 being my narrow specialty) but Kaosun knows everything there is to know about CD spinners  :yes:



#4 docs

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Posted 20 March 2019 - 03:46 PM

Hi, thanks for your responses.
I have lubed the moving parts and done some disconnects/reconnects.
If the initial reading of the disc works but then fails to take input and spin the disc but does work flawlessly if engaged immediately after turning on, motor moves fast, all tracks play good, weird?

I did find a faulty 10uf 35v cap in the power area which was visibly shot so I replaced it. I also saw 2 n15 fuses without continuity so replaced those too.

I’ll try any other components around that cap to see if it affected them too.

#5 hopey

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Posted 20 March 2019 - 05:42 PM

I would clean the lense again with alcohol, sounds like its having trouble registering the disc. And try a few different discs as some maybe flawed.



#6 docs

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Posted 21 March 2019 - 02:48 AM

Will try it but it does read the TOC fine, spins the disc a little gets the number of tracks on the disc in less than a second, then the problems begin.



#7 hopey

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Posted 21 March 2019 - 04:15 AM

there may be wear in the servo pinon gear so its not reponding fast enough and data is glitching.



#8 docs

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Posted 21 March 2019 - 04:46 AM

If I press play straight after turning it on, the servo works perfectly though, moving along the tracks smoothly and very fast to next and previous tracks etc, if I press to go to track 12 it goes there fast and if I go back to track 7 it goes there fast. I'm guessing that tracing voltages through the power section is a starting point but I've checked voltages at all IC's and they are all getting correct voltages. It's like after reading the disc the inputs just stop working but they work 100% if I engage them before it reads he disc.



#9 docs

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Posted 21 March 2019 - 03:21 PM

Done some voltage testing and cant see any issues yet.

#10 Jorge

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Posted 21 March 2019 - 09:21 PM

What a puzzle!! I am trying to see the difference between these two modes, and cannot think of one. Laser/Focus Check-Hit Stop Button-Read TOC-follow the instructions... What if the instructions are there before the checkup?  Try spraying DeoxIt on the inner sled Stop Switch: in some of my D-90 restorations it was totally bad... but without such symptoms.

If still nothing, then ask Kaosun, this is what I used to do maybe a bit too often. He always responds... even if sometimes it takes a few days or even weeks... But the Dude is younger than my son, just recently graduated, and already a legend among Discman Lovers. Busy with life'n'stuff, not hobbies...

 

On the schematics: which resistor went bad?



#11 docs

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Posted 22 March 2019 - 03:26 AM

Jorge do you have a contact for him, I tried registering over there but never got an email.

I think it was R209 off top of my head but I'm not 100%, I'll confirm when I get home later tonight.



#12 docs

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Posted 22 March 2019 - 12:49 PM

Yes R209 was the burnt out resistor replaced, which is 2.2k.

#13 Jorge

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Posted 22 March 2019 - 08:28 PM

I posted your request at kaosuncd.com:

 

Interesting Puzzle

 

While waiting for professional help, I will download CDP-7F service manual to maybe figure how R209 got burned and what else might have been affected



#14 docs

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Posted 23 March 2019 - 04:52 AM

Thank you so much Jorge, appreciate this very much.

#15 docs

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Posted 23 March 2019 - 11:46 AM

I’ve taken a look at the door closed switch because ic101 pin 5 is showing -1.5v instead of -5v. This microswitches usually have a click when being used and I don’t hear anything with this so I’m thinking it might be bad.

Will try find a replacement.

Attached File  5AF5A2FD-982A-4EAF-8AE2-481BF62590A3.png   721.8K   2 downloads

#16 docs

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Posted 23 March 2019 - 12:45 PM

Confirmed switch is faulty.

#17 Jorge

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Posted 23 March 2019 - 12:50 PM

Jump the switch until you find a substitute. Don't hit Play until you close the lid  :cool:

One of my D-50 MkII had lid switch removed permanently because of this same problem of the switch sometimes disengaging, I do nor remember ever damaging any CD. Usually you close the lid, Then hit Play



#18 docs

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Posted 24 March 2019 - 09:13 AM

Thanks Jorge, took that switch apart and back together with working continuity when switched and so far so good! Proper functions resumed!!!!!!

#19 Jorge

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Posted 24 March 2019 - 12:24 PM

Are you saying that now CDP-7F plays properly? 



#20 docs

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Posted 24 March 2019 - 02:49 PM

Just been through 30-40 discs and worked flawlessly, no issues now so yes all working!!!

#21 hopey

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Posted 25 March 2019 - 04:26 AM

Just been tbrough 30-40 discs and worked flawlessly, no issues now so yes all working!!!

 

Great work !