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active monitor fuse problems

Discussion in 'Recording' started by fallan, Oct 29, 2014.

  1. fallan

    fallan Active Member

    Hi again.. Recently there was a problem with the electricity lines outside my house sparks flying off it which then blew a fuse at the outside pole cutting of power to my house.Ive got a small recording studio away from it and when the power came back on I checked to see if my equipment was ok it was except my active monitors which didn't come on. I checked both power leads with other speakers Ive got and they came on ok. the slow blow glass fuses didn't seem to have blown but decided to buy some more anyway. Now the strange thing is when I put in the new fuses it powers up for about 2 seconds then goes off. When I check the new fuses they are black and are really blown yet the original fuses don't seem to blow but no power comes on even for a second after trying the speakers with them again. Sorry for this longwinded post but thought it would be better to give the whole story of why the speakers became faulty... any advice would be appreciated. cheers Frank
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  2. pcrecord

    pcrecord Don't you want the best recording like I do ? Well-Known Member

    First, are you sure the new fuses are the same value and kind of the originals ?
    Second, you should know that a slow blow may not seem blown to the eye, did you try to test them with a voltimeter ?
    Third, it is possible that the internal powersupply of the monitors have been damage and must be checked by an electronic technician.
     
  3. fallan

    fallan Active Member

    Hi PC,thanks for the input.. contacted the company and they told me what fuses to get.. then looked at the back of the speaker and the fuse I was sent was exactly like the originals T1AL... don't have a volt meter so couldn't test them that is why I decided to buy new ones... why the new ones blow and can see it black in the fuse and the old ones weren't discoloured seemed odd... regarding the internal power supply that might be gone and will have to have it looked at but why did power come on for 2 seconds if the PS has gone?
     
  4. Boswell

    Boswell Moderator Distinguished Member

    What make/model are these monitors?
     
  5. fallan

    fallan Active Member

    Samson Resolv65a they were stand in for my absolute 4s which has a tweeter problem Im having fixed
     
  6. Boswell

    Boswell Moderator Distinguished Member

    OK, this depends on how much fault finding you want to do. Those Resolv65a monitors are a bit unusual in having a standard mains transformer feeding a pair of bridge rectifiers for the +/-18V and +/-32V power rails, but that means that it's easier to narrow the fault down. If you don't want to do this work yourself, enlist the aid of a competent electronics engineer or an electrician.

    You need to unscrew the rear panel and locate the mains transformer. The primary side of the transformer is connected to the mains inlet connector (with fuse) and the two secondaries go via separate plugs and sockets to the two PSU circuits. You can independently disconnect and re-connect these secondary circuits to see whether it's one or both of them that overload the transformer, blowing the mains fuse.

    Take great care when working with 240V mains applied. Only make changes with the mains inlet connector fully unplugged.

    The 18V secondary circuit goes to its rectifiers via plug CN3 and the 32V circuit via plug CN2. Unplug CN2, CN3 and CON4 (the feed to the pre-amp and crossover board). Apply mains to the transformer (via a working fuse). If the fuse does not blow, the transformer is probably OK. Unplug the mains, plug in CN3 and re-apply mains. If the fuse blows, then at least the +/-18V circuit has a fault. Unplug CN3 and repeat the exercise with CN2. If the fuse is OK with both CN2 and CN3 inserted, try again with CON4 inserted. After this, you will have a better idea where the fault lies. Come back to us with the results.
     
    pcrecord likes this.
  7. fallan

    fallan Active Member

    Thanks for this input..Im deciding whether I take a look at it myself or take it to a local shop. So you are advising no power lead should be plugged in even if its switched off at the socket? Will let you know how I get on.. Thanks again for the advice.. Frank
     
  8. dvdhawk

    dvdhawk Well-Known Member

    I like how Boswell says, "Come back to us with the results", as if the rest of us could contribute anything near his level of knowledge and helpfulness. He has a handful of real peers here, but he must feel like he's trying to train labradoodles trying the educate the rest of us.

    Frank, you're in the best possible hands. And I don't mean to offend but if, "Only make changes with the mains inlet connector fully unplugged" isn't clear - I would urge you to "enlist the aid of a competent electronics engineer or an electrician", so you don't do further damage to your speakers, start a fire, or electrocute yourself. [in ascending order of consequence] The 3 seconds it would take to completely disconnect the power seems like a minor inconvenience to avoid unnecessary sparks, shocks, and unpleasant surprises. And even with the amplifier completely unplugged, you have to be aware of what you're touching, and realize there can still be electrical energy stored in the circuitry. (*see sparks, shocks, unpleasant surprises)

    Best of luck!
     
    DonnyAir likes this.
  9. fallan

    fallan Active Member

    LOL get your point... its my age you know its off to the local shop for me thanks DV
     
  10. Some Active Powered Monitors Automatically Shut off When There Is No Audio Input. They come on for a couple of seconds when first powered up. Then they shut off with no input. They automatically turn back on when there is input. You might have one of those types? I had a pair like that and they drove me crazy.
     
  11. pcrecord

    pcrecord Don't you want the best recording like I do ? Well-Known Member

    @Graham Bell Hertz :
    Those Samson Resolv65a were running fine until a power surge occured and when he replaces the fuses they just blow up again.
    After your post, I took time to download and read the manual and there is no auto shut off with those units.
     

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