Good amp gone bad. Attempt to fix. HELP!!!

Discussion in 'General Electronics Chat' started by jay-bee91, Dec 30, 2015.

  1. jay-bee91

    Thread Starter New Member

    Dec 30, 2015
    2
    0
    Hi everyone I have an acoustic solutions hi-fi amplifier that I've had for years and it's always been good to me until yesterday it suddenly stopped working, so I opened it up and noticed on the circuit board there were a few tacks in some of the tracks so I re-soldered them and also found a bad fuse by chance which I also replaced. But when I turned it on the LCD illuminated but wasn't showing anything and there is a loud buzz coming from the transformer... I turned it off and started looking for any bad components but I haven't noticed any by eye that are blown however I have noticed a resistor that's sort of flaking a bit but when I used my multi meter it seems fine... Does anyone know how to help me sort out this problem?
     
  2. ronv

    AAC Fanatic!

    Nov 12, 2008
    3,281
    1,232
    Most age related failures are capacitors. If you have a schematic someone might have some ideas on where to look.
     
  3. jay-bee91

    Thread Starter New Member

    Dec 30, 2015
    2
    0
    14515329070102140484822.jpg 1451533126691-1924123112.jpg 14515336897641368969457.jpg
    These are some pictures of the circuit boards
     
  4. wayneh

    Expert

    Sep 9, 2010
    12,090
    3,027
    I know you want to fix your old friend but you should look at what used gear sells for on e-bay. You might spend s lot of time to fix something worth $5. Spend $20 and get a big upgrade.

    Those flaky resistors are unusual. Could definitely be a clue. As suggested, it's probably bad caps. The easiest thing is to just replace every electrolytic on the board. Think of it as maintenance. If a problem persists, you may be stuck. A schematic and service manual would help a lot.
     
  5. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
    2,778
    1,216
    Sounds like a faulty (low-Z) Cap shorting the PSU --- FWIW I'd just replace all the large electrolytics in shunt with the power supply...

    Good luck!
    HP:)
     
  6. SLK001

    Well-Known Member

    Nov 29, 2011
    810
    224
    What is a "tack in the track"? Where's the picture of that? What do you mean by "flaking resistor"? Where is the picture of that? Did you even bother to do any voltage measurements?

    You will probably find your problem on that giant heatsink wall, specifically, the main stereo amplifier.
     
  7. bwilliams60

    Active Member

    Nov 18, 2012
    722
    88
    Agreed on the electrolytics. With the age of the unit, it might not hurt to look over all the solder joints as well and make sure there are no broken or loose joints. Do you have an ESR meter to check them or even a capacitance meter? Both of these will tell you if you are on the right track.
     
  8. bertus

    Administrator

    Apr 5, 2008
    15,645
    2,344
    Hello,

    Those resistors that gone flaky might be due to to much heat aka. power dissipated in them.
    It could be that the caps make to large ripple wich could cause this.
    When you replace the caps, I would also replace the resistors.

    Bertus
     
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