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Any electronic gurus out there??? HELP

Discussion in 'The Lounge' started by mr.smartass, Dec 20, 2006.

  1. mr.smartass

    mr.smartass 1 ton status Premium Member

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    I was given a stereo receiver by a friend who just said it didn't work. I opened it up and found what apparently is the problem. It has a small blown fuse and some type of resistor or whatever burned. I'm simply need to know if it can be soldered, replaced or just throw it away, besides this everything seems to be in working order. It's a sony reciever. Here are some pics, should would be nice to have a free stereo for the shop.

    Sorry pics are blurry, had a hard time getting the light and stuff right, plus it's a cheapo kodak camera...
    [​IMG]

    The one all the way to the left is the one that the built in smoke came out of.
    [​IMG]

    A blurry picture of the little blown fuse.
    [​IMG]

    [​IMG]


    Another blurry pic of the object in question...
    [​IMG]

    Best of the pics. Shows exactly what the problem is. There really isn't any metal exposed to solder to... any have any advice?
    [​IMG]

    Any help is appreciated. Or if you have any ideas of where I can post these pics up, like another forum or something let me know, thanks.

    Justin
     
  2. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    Thats a transistor . If your lucky replacing those will fix it , however other components may need replacing too .
     
  3. mr.smartass

    mr.smartass 1 ton status Premium Member

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    Ok www.mcminone.com has them for $4 and some change... Any idea on how to test them with a ohm meter? If it is shorted it should be 0 ohms no matter what, right? Just want to test the others before I order one... I inspected the rest of the boards and didn't see anything burnt, what should I be looking for? What are the chances of a radioshack or something have one?
     
  4. pauly383

    pauly383 Daddy383 Staff Member Moderator

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  5. mr.smartass

    mr.smartass 1 ton status Premium Member

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    cool, good info, I guess all DMM have a diode test function ehh? I better make sure... the only problem is that it says it's only for out of circuit transistors and I don't plan on clipping all of them and testing them... lol. But i'll give it a shot anyways. Thanks man.
     
  6. diesel4me

    diesel4me 1 ton status Premium Member

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    I am no expert,but it looks like..

    I'd guess that is one of the output transistors for one channel...you may be able to buy one like it at Radio Shack--they have an interchange book you can cross the numbers off the old one to their number...but I kind of doubt that is ALL that got fried,but maybe you'll get lucky!..

    I have "rebuilt" a few car stereo's that had blown output transistors successfully..I soldered the new ones right onto the "legs" of the old one,rather than try soldering on the printed curcuit board..never was any good at that!..:crazy:
     
  7. newyorkin

    newyorkin 1 ton status

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    I went through this with a high voltage rectifier controller recently, lightning blew a transistor, which then caused fuses to blow. That was a beotch, 30 transisors and fuses per board, two boards for each supply, 4 supplies (I knew which supply had a problem, so I didn't have to check each one)...

    In the end, one transistor was shorted. I tested them in-circuit for shorts and found one. You can test them in-circuit for direct shorts, but it's not terribly reliable.

    Make sure you replace it with an identical part number. That looks like it's an amplifier, so to keep your audio sounding ok, you'd want to avoid different-spec'd replacements. $4 is probably about the right price.

    You can clip off the bad transistor at the leads as close to it's body as possible, then try to solder the replacement onto the old leads to avoid trying to solder the board. Heating up the leads will probably melt the board solder and you may end up with a cold solder joint on the board contacts, but that's how I'd approach it. Try to heat the old leads as fast as possible so they conduct less heat down to the board.

    I'm certainly no expert and someone will probably correct me, but I would guess that 1 amp shorted. Once it shorted, it let too much current through, which melted the lead and blew the fuse. Transistors go bad for lots of reasons, but they're generally pretty reliable. Could have been a surge, could have been too little cooling, etc. There could be other components bad, but I'd do the amp (most obvious) and see what that does before chasing anything else.
     
  8. mr.smartass

    mr.smartass 1 ton status Premium Member

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    Well I just called the local radioshack... useless people as I expected lol, They told me they couldn't do anything with a part number but maybe if I could give them ohm specs and stuff like that, they might be able to help... Well I said screw it and called around to some of the local guys on place said they can get it but it'd be a week after Christmas... I'm now waiting on the other guy to call me back, but everyone knows how that goes so I'll probably try back a little later.
     
  9. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    I don't like Radio Shack anymore , they are helping kill off radio . They may as well be called Best Buy or Comp Usa .

    Most of the ones here just have a small self service drawer set with the basic common stuff only .
     
  10. diesel4me

    diesel4me 1 ton status Premium Member

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    just like parts stores!..

    If I were to walk into our local Radio Shack and ask for that transistor,I'd likely get the deer in the headlights look,and the usual "DUH",I dont think we sell those here"...I would by-pass the counter monkey unless they seemed to know their stuff (a rarity!),and just ask to look in their big catalog of "special order" items,that has the OEM number interchange,and help myself!..many times I find just what I need on the shelf,after they tell me they dont have it!..

    I went there a few months ago to buy some doides I needed,for a car we swapped a GM alternator into, that had a generator originally(car would keep running when you shut the key off,without adding a diode!)..--they were completely clueless,so I told them to go sell the other customers a cell phone,and I'd look around..I found the diodes I needed hanging on a pegboard hook,the very ones the guy said "we cant get those ,I think"....:doah:


    I wonder how stores like that stay in bussiness..must be due to all the other crap they DO sell,like cell phones and "Direct TV",etc..not because of their knowledgeable counter persons..same goes for auto parts stores lately..they can sell bling stuff,dirt bikes,etc--anything but parts,if they cant look it up on their computer its "unavailable"..:surepal: :surepal:
     
  11. newyorkin

    newyorkin 1 ton status

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    There's often a lot of talk in the radio industry among engineers about how Radio Shack is a cell phone and gadget store now.

    The original name Radio Shack was a reference to Ham radio shacks, cause Radio Shack had and provided a lot of the components hams would use to build thier rigs.
    This thread reminds me, I've forgotten for the 3rd day in a row to stop there for a power supply. I could have mail-ordered it by now...
     
  12. mr.smartass

    mr.smartass 1 ton status Premium Member

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    Well I finally took the time to do it... solder the thing in, got it all back together put the new fuse in, now it will turn on and look like it's gonna work, then starts flashing the word protector on the screen... any ideas? does it every time....
     
  13. Jagged

    Jagged 1 ton status

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    My Radio Shack down the street has ham radio stuff. Me and the locals call that particular store "The Candy Store"

    G5RV antennas, Yagi's, 2m/440 mobile rigs, HF rigs, old school vaccuum tube radios, books, parts, more antennas... yeah!
     
  14. filo

    filo Registered Member

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    Sounds like that's the protection circuit not letting power through. There's most likely too much voltage...somewhere.
    Did you replace the transistor with the exact part number, or close? (which I've done many times);)
    One thing to think about also is the original reason the fuse and transistor blew. Either the transistor went out and took the fuse with it, or something else caused both to go out. It's possible you still have the original problem.:dunno:
     
  15. mr.smartass

    mr.smartass 1 ton status Premium Member

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    I did some searching and apparently alot of people get it for different reasons. I might need to replace the transistor next to to burned one as well... The protector message pops up when something is shorted... from speaker jacks to any internal part... guess I'll spend a little more timing inspecting it.
     

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