Author Topic: Tough Problem To Locate Need Help  (Read 15107 times)

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Offline tony3d

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Tough Problem To Locate Need Help
« on: April 22, 2016, 01:24:55 pm »
Hi all, I have been into electronics now for about a year, and have learned a lot from this site. Don't replay have the expertise to repair things yet, but I am learning. I have an issue with one of my HIFI Components, a Harman Kardon CDR26 Cd recorder. It has a playback cd drive on the left, and a record unit on the right. The unit on the right works fine, the one on the left fails to read a disc, and comes up with disc error after several attempts to read it. At first it had every sign of a failing Laser, because it gradually became worse. So, I found the play drive on Ebay, bought it, replaced it, and had the exact same problem. I had noticed that The unit would sometime read when it heated up a bit, so while I had it opened I got a hair dryer out and just heated the board in different areas, and found it would read instantly, and play fine so long as the board was warm. So I narrowed it down to this area of the board, but really can't see anything very obvious. I mean it's so sensitive I can hold the dryer 3 feet away for 5 seconds, and it will work! Going to be very hard to locate. I only have a solder station with no special attachments. Closest thing I have is a very small ball tip. There are a lot of surface mount components here I would rather not ouch LOL! Any suggestions would be great! By the way H/K no longer repairs this machine. I took apart all the ribbon cables, and checked the continuity of them with my Fluke, and all were fine.
 

Offline Whales

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Re: Tough Problem To Locate Need Help
« Reply #1 on: April 22, 2016, 01:30:43 pm »
See if you can narrow down the problem further using your hot air.  Try heating only a small part of your board and slowly heat more sections until the problems disappears.

Offline Codemonkey

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Re: Tough Problem To Locate Need Help
« Reply #2 on: April 22, 2016, 01:33:35 pm »
If you can't heat a small section of the board, you could heat it all up until it works and then use some freeze spray to cool bits selectively until it doesn't work.
 

Offline Whales

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Re: Tough Problem To Locate Need Help
« Reply #3 on: April 22, 2016, 01:39:26 pm »
Can you 'constantly' test the board or do you have to perform an action (eg pressing a button and waiting) after heating it to check if it works?

If you can constantly test the board then try pressing the SMD components against the board, one by one, with a wooden skewer.

Offline CJay

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Re: Tough Problem To Locate Need Help
« Reply #4 on: April 22, 2016, 02:05:07 pm »
Always always check the basics first.

Visual:
Are there any components showing signs of stress, I.E. are they or the board around them discoloured, have any capacitors tilted over or swollen up?

Electrical:

Does it have the correct/sensible voltages coming onto the board? You can check when it's cold and faulty and again when it's working.

Do the voltages make it to the relevant chips? (you can usually find datasheets or at least pin outs for most chips)

Are there any crystals on the board, are they oscillating? A missing clock signal will cause all sorts of problems.

Does the disk spin?

Do not look at it directly but does the laser light up? (an infra red laser as used in a CD player will, when viewed at an offset angle)

M0UAW
 

Offline tony3d

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Re: Tough Problem To Locate Need Help
« Reply #5 on: April 22, 2016, 03:11:09 pm »
Can you 'constantly' test the board or do you have to perform an action (eg pressing a button and waiting) after heating it to check if it works?

If you can constantly test the board then try pressing the SMD components against the board, one by one, with a wooden skewer.

I can constantly test the board because the sound will begin to Crackle as the board cools. I'll give this a try. I see no physical defect that looks suspicious. This section of the board I'm showing is definitely the area the problem exists in. the heat does not effect the right side of the board which I believe is the record decks side, which works fine. This is so frustrating, but at least I'm on the right  track.
 

Offline mij59

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Re: Tough Problem To Locate Need Help
« Reply #6 on: April 22, 2016, 03:22:49 pm »
Seems to me the solder joint of the bottom left cap is broken.
Check the SMD cap's with an ESR meter.
Check for dust etc. on the lens of the laser.
 

Offline tony3d

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Re: Tough Problem To Locate Need Help
« Reply #7 on: April 22, 2016, 03:23:20 pm »
If you can't heat a small section of the board, you could heat it all up until it works and then use some freeze spray to cool bits selectively until it doesn't work.

Now that Radio Shack is gone where can I get a can of this spray?
 

Offline dacman

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Re: Tough Problem To Locate Need Help
« Reply #8 on: April 22, 2016, 03:43:32 pm »
You could use canned air upside down.
 

Offline cvanc

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Re: Tough Problem To Locate Need Help
« Reply #9 on: April 22, 2016, 06:58:58 pm »
Solder joint in question (and sharp eyes for finding it!):
« Last Edit: April 22, 2016, 07:00:32 pm by cvanc »
 

Offline tony3d

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Re: Tough Problem To Locate Need Help
« Reply #10 on: April 22, 2016, 10:42:04 pm »
Solder joint in question (and sharp eyes for finding it!):


Yes, I'm going to hit that tomorrow! Looks like that may be it!
 

Offline DimitriP

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Re: Tough Problem To Locate Need Help
« Reply #11 on: April 22, 2016, 11:11:45 pm »
The pins on the left side of IC 403 don't look quite right.
Also the ribbon cable is plugged in at an angle. The left side looks like it's almost out.


   If three 100  Ohm resistors are connected in parallel, and in series with a 200 Ohm resistor, how many resistors do you have? 
 

Offline tony3d

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Re: Tough Problem To Locate Need Help
« Reply #12 on: April 25, 2016, 04:39:06 pm »
Have tried everything. Pressed down on almost every component with a pencil eraser, Touched the cap in question with a soldering tip, straightened the ribbon cable, and pressed down on a variety of traces with the pencil eraser. Yet, if I hit just even  the top right corner of the board with a hairdryer on low heat for only 5-10 seconds, it works! OMG!!
 

Offline DimitriP

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Re: Tough Problem To Locate Need Help
« Reply #13 on: April 25, 2016, 05:05:53 pm »
Sounds lke it's time for some signal probin'. Do you have a schematic, or more importantly a 'scope?
   If three 100  Ohm resistors are connected in parallel, and in series with a 200 Ohm resistor, how many resistors do you have? 
 

Offline mij59

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Re: Tough Problem To Locate Need Help
« Reply #14 on: April 25, 2016, 05:10:33 pm »
Maybe there's intermittent contact in L442, could be part of a power rail for IC403.
 

Offline miguelvp

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Re: Tough Problem To Locate Need Help
« Reply #15 on: April 25, 2016, 05:12:53 pm »
... it works! OMG!!

Seems he fixed it.
 

Offline tony3d

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Re: Tough Problem To Locate Need Help
« Reply #16 on: April 25, 2016, 05:37:56 pm »
No, I meant after holding the heat for that length of time, it works. I think I have narrowed down to two components. The electrolytic cap in this image or the one above, soon as I hit these two with cold air it stops working! Touched both sides of the cap with my solder station, and no dice. not sure how to tackle the one above. pressing on either does nothing. Wonder if the cap is bad?
« Last Edit: April 25, 2016, 05:47:35 pm by tony3d »
 

Offline tony3d

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Re: Tough Problem To Locate Need Help
« Reply #17 on: April 25, 2016, 05:55:28 pm »
Maybe there's intermittent contact in L442, could be part of a power rail for IC403.

I do have a cheap OWon Scope! Like I say I'm still a beginner. I'm really not sure what that L442 component is? Is it a resistor or a cap?
« Last Edit: April 25, 2016, 06:04:27 pm by tony3d »
 

Offline DimitriP

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Re: Tough Problem To Locate Need Help
« Reply #18 on: April 25, 2016, 06:37:06 pm »
Maybe there's intermittent contact in L442, could be part of a power rail for IC403.

I do have a cheap OWon Scope! Like I say I'm still a beginner. I'm really not sure what that L442 component is? Is it a resistor or a cap?

Neither 
Take a look and here https://en.wikipedia.org/wiki/Reference_designator and  there will be a quiz later


   If three 100  Ohm resistors are connected in parallel, and in series with a 200 Ohm resistor, how many resistors do you have? 
 

Offline tony3d

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Re: Tough Problem To Locate Need Help
« Reply #19 on: April 25, 2016, 06:51:28 pm »
Maybe there's intermittent contact in L442, could be part of a power rail for IC403.

I do have a cheap OWon Scope! Like I say I'm still a beginner. I'm really not sure what that L442 component is? Is it a resistor or a cap?

Neither 
Take a look and here https://en.wikipedia.org/wiki/Reference_designator and  there will be a quiz later

 So it's an Inductor?
 

Offline tony3d

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Re: Tough Problem To Locate Need Help
« Reply #20 on: April 25, 2016, 06:55:01 pm »
I'm just hoping it's not this Sony Cxd3023r DAC. It's discontinued! Probably why H/K won't repair it anymore?
 

Offline stmdude

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Re: Tough Problem To Locate Need Help
« Reply #21 on: April 25, 2016, 06:57:28 pm »
So it's an Inductor?

Correct.  The most basic test of an inductor would be to check continuity and/or resistance. It should be close to 0 ohms.
Try checking on the component, and away from it (as in, the component it's connected to, a via, etc), to check the solder.

The component has wide legs that are wrapped underneath it. You should be able to re-flow it by simply holding your iron against the metal side until the solder underneath melts. Repeat for the other side.
 

Offline tony3d

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Re: Tough Problem To Locate Need Help
« Reply #22 on: April 25, 2016, 07:18:21 pm »
I'm getting between .2-.4 Ohms, and it does have continuity. I'm really beginning to think it's that Sony Dac Which is discontinued! Did touch both sides with the solder tip, made no difference. Can hold the hear 2 feet away for just seconds, and it plays fine. Really weird!
« Last Edit: April 25, 2016, 07:20:19 pm by tony3d »
 

Offline tony3d

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Re: Tough Problem To Locate Need Help
« Reply #23 on: April 25, 2016, 07:28:57 pm »
I think I'm going to have to give up on this player, and just use the right deck. Really close, but no prize! I don't see anything else on the board that looks off in this area. I have touched multiple point with my iron. I think it could be that chip itself! Maybe there's a disconnect inside?
 

Offline tony3d

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Re: Tough Problem To Locate Need Help
« Reply #24 on: April 25, 2016, 07:30:47 pm »
Almost considering mounting a small heater to the bottom of the lid. it just needs to be heated slightly. It's a bandaid, but hey if it works......LOL!
 


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