Need help with repairing a Yamaha HT Receiver

Discussion in 'General Electronics Chat' started by Fastmerc, Feb 20, 2015.

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  1. Fastmerc

    Thread Starter New Member

    Feb 20, 2015
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    Hello all,

    First let me thank the forum in advance for any help provided!

    Bit of backround, I am not any kind of trained EE or even a repair guy per say. Just a healty DIY guy with an inquisitive nature. I am good enough at soldering to have repaired several of my home electronics items with success as long as I know to put this thingamajig in that hole and solder it. So what Im saying is I don't understand the how or the why something works but I am decent at following instructions...lol.

    Ok, now on my issue. I have a Yamaha RX-Z1 HT Receiver and I really enjoy it. There apparently is a common issue with these that one of the 5 volt IC chips goes bad. It had happened to this one a number of years ago. I found some threads that said which part to replace, ordered one and had a friend put it in. It lasted about a year or so then went out again. It has been sitting for another couple of years in my closet, but now I want to get it back up and running.

    I'm better at soldering now than I was way back and want to just do the repair myself. I have taken the unit apart to the area I need to fix. Now the problem is when I went to order the part, it is no longer available and obsolete. Digi key suggested a replacement. I have two questions I am hoping you can help me with.

    1) I will link the two data sheets of the components, and if you could tell me if in fact this would be the appropriate replacement. Im pretty sure Digikey has a handle on it, but just want to make sure.

    Original part http://sharp-world.com/products/device-china/lineup/data/pdf/datasheet/pq05rd11_e.pdf

    Replacement http://media.digikey.com/pdf/Data Sheets/Sharp PDFs/PQ05RR12,13.pdf

    2) Is there something that might be making this part go bad and that should be looked at? I downloaded a service manual and could probably put up the link if anyone needs that.
     
  2. wayneh

    Expert

    Sep 9, 2010
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    I agree that the newer part should be fine. It has a slightly higher voltage rating, which may help it survive longer. Did the original have a heat sink on it? If not, I'd consider adding one if you have room.

    You might take a look at the input voltage and the capacitor there, as well as the output capacitor. Just replace the caps unless you can test them for ESR.
     
  3. Fastmerc

    Thread Starter New Member

    Feb 20, 2015
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    Here are some photos of the board and the probable culprit. The entire board was attached to a very large heatsink, so thats good. I will read up on testing the caps for ESR but I have a feeling I don't have the correct meter for that. Also I notice the two IC's on either side of the one that supposedly goes bad are the same parts, should I replace them as well? Do they have anything to do with each other? Is there a way to test these IC's with a multi meter to make sure they are bad?

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  4. wayneh

    Expert

    Sep 9, 2010
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    If you don't have an ESR meter, it's simplest to just replace the caps. They age anyway, so you gain some "freshness" even if they aren't yet failed. I'm guessing it would be the medium-sized caps nearest the regulators, but it's hard to tell for sure without tracing the circuit. Those big ones may be worth a look as well.

    You could test the regulators out of circuit, but I can't think how you'd do that safely without removing them from the board. When I need to remove a component like that, I have a gun-type iron with a flat, broad spade tip. It can contact all 4 pins at once and that makes it handy to pop out the IC in one quick motion.
     
  5. bwilliams60

    Active Member

    Nov 18, 2012
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    There is a company in California called Quest Electronics showing 47 of your original chip in stock. Might give them a look. Usually replace them as a set. Agree with wayneh regarding caps. For the price of them, cheap repair and nice to start fresh.
     
  6. wayneh

    Expert

    Sep 9, 2010
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    That's an awful lot of heat sink paste. It would be better to have only a thin layer.
     
  7. #12

    Expert

    Nov 30, 2010
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    It would be better to NEED only a thin layer. If the heat sink surface is that irregular, you have a problem. If it's nice and smooth, the extra will squish out.
     
  8. Fastmerc

    Thread Starter New Member

    Feb 20, 2015
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    Thanks so much for that. I just checked it out, however their minimum order is 25.00 and at most I need three of these, six if I decide to have a backup set. If the replacements from Digikey might be a better alternative due to the higher voltage rating maybe they would be better to go with anyway?
     
  9. Fastmerc

    Thread Starter New Member

    Feb 20, 2015
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    It seems to be a pretty smooth heat sink surface, I will clean everything off and put a new thinner layer on when I put it back together. Good to learn things like this.
     
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  10. bwilliams60

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    Nov 18, 2012
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  11. wayneh

    Expert

    Sep 9, 2010
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    Frankly I wouldn't be so hot to use the original part, given its failure rate.
     
  12. bwilliams60

    Active Member

    Nov 18, 2012
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    Good point but I am wondering if OP has replaced the same part or all of them. Looking at the date code, I would guess that he has only replaced one and perhaps he has more issues further down the line that need to be addressed. If the other ones are original, I would say they are doing a good job. If they have all been replaced, then replace them all with updated new improved version. Measure caps and resistors to ensure no other problems
     
  13. Fastmerc

    Thread Starter New Member

    Feb 20, 2015
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    The original repair only had the single IC changed out and nothing else. According to what I read at the time that part in that position on the board is a common failure. Im not sure why the other two positions seem to be ok. If it is suggested I replace all three with the new ones I certainly will do it. I would love this thing to last more than another year, I paid a buttload of money for it originally.
     
  14. Brevor

    Active Member

    Apr 9, 2011
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    My vote is just replace the bad one, also if you are really fond of this receiver i would suggest you get several extra spares. Thats not a very popular part and you never know when they all may be discontinued.
     
  15. bwilliams60

    Active Member

    Nov 18, 2012
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    It would be nice to know what the cause of the problem is instead of fixing the effect all the time. Me personally, I would replace all three and keep them the same.
     
  16. Fastmerc

    Thread Starter New Member

    Feb 20, 2015
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    I totally agree, sadly with my limited understanding of the how and why part I wouldn't even begin to know where to look. I would be happy to link the service manual download if anyone wants to take a crack at the schematics.

    I decided to order the newer replacement parts and see what happens. I will try and take a closer look at the caps and see what I can come up with this weekend.

    Thanks to everyone for all the help so far!
     
  17. bwilliams60

    Active Member

    Nov 18, 2012
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    If you have the service manual, don't be shy. Dump it on us, we won't mind :). Always looking to add to the library.
     
  18. Fastmerc

    Thread Starter New Member

    Feb 20, 2015
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  19. Fastmerc

    Thread Starter New Member

    Feb 20, 2015
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    Ok so I got the new parts in. For now I just replaced the suspect part, put the unit back together and it did not fix the issue. How can I test the part I just pulled off to see if it was functioning properly?
    I still have the other two to replace if needed but now I would like to test them so I can explore further if I need to.
     
  20. Fastmerc

    Thread Starter New Member

    Feb 20, 2015
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    While waiting I replaced the other 2, still have the same issue. Im kinda bummed now. Anyone know where I should start looking next.
     
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