jbl 601.1 car audio amplifier

Discussion in 'General Electronics Chat' started by craig155, Jul 23, 2008.

  1. craig155

    Thread Starter Active Member

    Jul 21, 2008
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    Hi all,
    Noob here with a couple of questions,
    I have lost the audio output on my amplifier and the protection light is on, looking at the amp it appears two 22yf 16v resistors have blown, what now does it matter which way round you fit these and also i have been told that the output transistors(?) could be blown also.
    I have the repair manual but it doesnt mean much to me, please help.

    Thanks,

    Craig.
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    Craig, please re-read the specifications. I believe you'll find that they actually say 22uF 16v. They are not resistors, they are electrolytic capacitors. If the tops or ends of your capacitors are bulging or blown out, they need to be replaced.

    Look closely at the capacitors. There should either be a stripe on one side, or the letters 'NP'. 'NP' means that the caps are "non polarized'; polarity does not matter, and you must use NP electrolytic caps as replacements. If there is a stripe on the side or end, that will be the negative side in the case of aluminum electrolytics. Tantalum capacitors have their positive side marked. It's important to know which type of cap you're dealing with. Your repair manual should have a list of components that were used in the amplifier.

    That is a possibility, but try replacing the capacitors first.

    Do you have a digital camera? Take a couple of close-in shots of the caps so that we can help you identify them.

    Capacitors come in a bewildering array of shapes and sizes. You'll need to get a replacement that at least has leads that will reach to the board's traces, and the same physical size or smaller than the original.
     
  3. craig155

    Thread Starter Active Member

    Jul 21, 2008
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    Hi, thanks for the reply.
    I have attached a diagram with arrow pointing to the two replaced parts, the board does not have on +tive or -tive so i presume it dos not matter which way they are installed?
    Thanks for the help.

    Craig.
     
    • amp.doc
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  4. craig155

    Thread Starter Active Member

    Jul 21, 2008
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    the part description is showing these as ceramic tubular 50v capacitors 102pf but the blown ones were tubular alloy type as they were lying near where they came from.
    I may have guessed on them being the same as surrounding components.
     
  5. SgtWookie

    Expert

    Jul 17, 2007
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    Funny, those look more like 1206 or 0805 size surface-mount (SMT/SMD) capacitors. It's really hard to tell from the schematic, as the resolution is not high enough to read the text.

    If the capacitors were blown right off the board, and read 22uF 16V, they would be either aluminum electrolytic or tantalum capacitors. They would be a good bit larger than the little SMT caps and resistors. Just because parts are close together, does not mean that they are the same type or value.

    Instead of scanning into a Word document, it would be easier to view if you scanned it into MS Paint (Start -> Programs -> Accessories -> Paint).
    Try doubling the current resolution setting. Save the output file as a .PNG. That should help make the image much more clear.
     
  6. craig155

    Thread Starter Active Member

    Jul 21, 2008
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    try this, it is in paint.
     
  7. craig155

    Thread Starter Active Member

    Jul 21, 2008
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    this one may be better.
     
    • amp3.PNG
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  8. SgtWookie

    Expert

    Jul 17, 2007
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    Ok, they're using a combination of 2-digit and 3-digit capacitance values, which is going to be confusing. If a three-digit number is followed by a "P", the first two digits are the value, the 3rd is the multiplier (number of zeroes to add); so 102P becomes 1000pF, or 1nF. If it's a 2-digit number followed by a "P", it's the actual value in pF.

    C107 = 102 = 10x100 = 1,000pF = 1nF
    C156 = 22pF

    The larger capacitors are marked in uF; the 3rd digit isn't a multiplier.
    What is surprising is that all of the polarized caps have their "+" terminal marked. This suggests that they are all tantalum capacitors. However, it may be that they simply marked them all that way to be consistent, but that leaves not much of a clue as to what they actually are.

    As I believe I mentioned before, the physical part will have either it's - or it's + terminal marked. Aluminum electrolytics have their - terminal side marked, usually with a stripe that contains a '-' sign. Tantalum caps have their + terminal marked, generally with a "+" sign, and maybe a stripe.

    It can be confusing.

    Did parts get blown off the board?

    Any chance that you can photograph the board so that we can see the devastation?
     
  9. craig155

    Thread Starter Active Member

    Jul 21, 2008
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    so what capacitors do i need, as the ones that were apart were the round alloy ones and unfortunately the description on the plastic on the side of them is unreadable.
    i only have a camera phone but i can get some decent photos tomorrow.

    Craig.
     
  10. craig155

    Thread Starter Active Member

    Jul 21, 2008
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    this is the best i can do at the moment.

    the ones i replaced are on longer wire than the rest, but the old ones are longer and fatter than these.
     
  11. SgtWookie

    Expert

    Jul 17, 2007
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    Well, it's hard to see much from that photo, but it looks like the large caps are aluminum electrolytic rather than tantalum. They appear to have rather shiny aluminium tops and wrapped in plastic, right?

    Have a look at the mark-up of a section of your parts placement diagram. You made arrows to the caps boxed in red, but the larger caps boxed in green are the electrolytics.

    Which are the actual capacitors that you replaced?
     
  12. craig155

    Thread Starter Active Member

    Jul 21, 2008
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    the capacitors that are marked as red are the ones i replaced, thats where it gets confusing because they were alloy wrapped in plastic thats why i replaced them with similar that are shown around them but according to the manual description sheet they should be ceramic tubular 50v 102pf.
    pity i cant read the plastic wrap as it has shrunk.
     
  13. SgtWookie

    Expert

    Jul 17, 2007
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    Well, they actually could be 102pF. Those are E96/E192 standard values; not typical for a hobbyist to have lying around.

    If the parts list specifies 50v 102pF, then you won't be able to use an electrolytic or tantalum cap, that's for certain.
     
  14. craig155

    Thread Starter Active Member

    Jul 21, 2008
    33
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    why would they be on there originally though?
    does that mean i will have to get ceramic capacitors then?
     
  15. SgtWookie

    Expert

    Jul 17, 2007
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    You should replace the caps with what's specified in the parts list.

    If you don't, I can't tell you what will happen offhand, except that it won't work like it should. You have only shown the parts placement diagram, not the schematic nor the parts list.
     
  16. craig155

    Thread Starter Active Member

    Jul 21, 2008
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    will it help to send those for you to look at?
     
  17. SgtWookie

    Expert

    Jul 17, 2007
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    Put them in an attachment, like you did for the parts placement.
     
  18. craig155

    Thread Starter Active Member

    Jul 21, 2008
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    it wont let me send them as attachments as they are over 2mb, what can i do?
     
  19. SgtWookie

    Expert

    Jul 17, 2007
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    Yikes! :eek:

    Did you try to scan them as black and white?

    Color images will be far too large; even greyscale would be too big.
     
  20. craig155

    Thread Starter Active Member

    Jul 21, 2008
    33
    0
    try this, i can only send these through a couple of pages at a time.
     
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