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Rotel RB 985 internal fuse location

Discussion in 'AV Pre-Amp/Processors & Power Amps' started by Kazman, Sep 19, 2005.

  1. Kazman

    Kazman
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    I suspect the fuse has blown on my Rotel RB 985 Mk1, I'm going to try changing the plug fuse tomorrow, if that doesnt fix things, I think it must be the internal fuse.

    Anyone know what type of fuse it uses and where to find one? Where is it located within the unit?

    Thanks in advance for any help.
     
  2. Kazman

    Kazman
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    Anyone?
     
  3. John Watts

    John Watts
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    I cant really help you mate exept to tell you that when you do find out what fuse you need MAPLINS will almost certainly sell one.
    If not try e-mailing ROTEL for a spare.

    Good luck mate,
    John.
     
  4. Paul Smith

    Paul Smith
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    This is also probably not much help but,
    I replaced fuses on one or two of the channels on my Rotel 985 (when I had one), as a couple of fuses had blown, my own fault.
    Those fuses were found in a logical relation to the channel used and I think were 6.3 fast blow (bought from maplins, I've still got a pack with 8 lying about).

    Paul.
     
  5. Kazman

    Kazman
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    Right, going to pick up the fuses tonight.

    Spoke to Rotel, and the fuses they recommended were T6.3 20mm, so looks like they are slow blow ones rather than fast blow.

    Going to pick up some banana plugs as well, as trying to connect speaker wire to the terminals without a banana plug at the back of this amp is a right pain in the backside I can tell you!!

    Hopefully will get this baby up and running to full strength after tonight :)

    Wish me luck :)
     
  6. Angry the Clown

    Angry the Clown
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    That's an obscene understatement really. The 985 honestly has the worst binding posts I have ever had the misfortune of having to deal with whether using bare wire or banana plugs (the latter sit rather loose in some, not all, of the rear ports - on my model at least).

    My 985 gives me a few troubles that I am unsure about finding out how to source. I've been contemplating taking the lid off it myself and trying to locate the problem though the prospect strikes me as somewhat daunting. It's picking up a fair bit of mains hum which I don't think can be helped, noise being most noticeable from seating distance in my left surround in quiet scenes. Not sure why one channel would be specifically bad but it is annoying in quiet scenes of films, and I don't own many noisy films if truth be told.

    The main problem is on occasion my 985mk1 has an infuriating tendency to make a strange noise every twenty seconds or so… It did this last night, and it drives me mad to the point where I just switch everything off and stop watching the film viea the home cinema set up because it's too distracting. I'd love to find out what it is. It's well ventilated really, and it's not something I put down to heat anyway since it only does it on the odd occasion as I say, and last night it began making the noise within thirty minutes of viewing though when I touched the amp itself it was running nice and cool…

    Anyone know what it all could be? It's difficult to explain the noise… if any Futurama fan is reading the closest approximation I could give of the sound is a four second burns of the Hypnotoad sound. :) It's this odd “bwarrgggg” sound for about four-five seconds, repeating every twenty-thirty seconds. I really wish I could replace the 985 with something better, but it's not really a priority right now. If I could fix it I'd be happier for a little while longer.
     
  7. Kazman

    Kazman
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    ATC! You aren't half right mate, those binding posts are a real pain, easily the worst I have EVER come across :).

    You say the bananaplugs aren't much better on it?

    I've been using bare wire on those binding posts and it just drives me up the wall at how easily they slip out, it's very difficult to secure them properly, and I've spent hours on it.

    Otherwise, it is a fantastic amp, and I got it for a bargain £200, so am not complaining :).

    I might move onto a parasound power amp soon, I've liked what I've heard previously and the look of the Halo amps is just plain gorgeous :).
     
  8. Angry the Clown

    Angry the Clown
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    On mine specifically, no they're not. A couple sit really loose in the ports, whereas those for other channels slot in securely. If the speaker cable is quite heavy I sometimes found it is just as easy to knock out the bananas by accident, though the saving grace is they're never as much of a task to connect back into place!

    I've got it all connected bare wire at the moment but and going to go back to plugs. My CRT television is so heavy in weight that it weighs my AV unit down to the point where it is just impossible to pull the unit forward and get to the back for easy access to all the ports for interconnects and so on. This results in having to re-connect cables blind all the time, which is a nightmare quite frankly, and the thought of accidentally knocking the Rotel binding posts and having to re-connect the speaker cables blind is too horrific a thought. So, to spare myself the Hulk like rage such an occurrence would surely bring about, I'm safer going back to the bananas.

    I just hope I can solve the noise problems that my 985 produces. I got mine cheap a few years back too, and it has served me well, but being noisy to the point of distraction and putting me off watching anything is not on, so I hope I can get to the bottom of it.
     
  9. Kazman

    Kazman
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    I might go for a Parasound 1205A if I can find one at a decent price, I REALLY want an A52, but alas, probably can't justify that kind of outlay right now, especially after shelling out nearly £2000 over the last few months on my kit.

    Didn't get a chance to sort out the RB 985 last night, so will probably do that tonight, was stuck in some really nasty traffic in Luton town centre :mad: stupid road planners have really messed up the layout, it is causing so many headaches, I hate going there to shop now, I just head into Brent Cross or Milton Keynes for shopping now, much less of a headache.
     
  10. Kazman

    Kazman
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    Right, managed to find some time to get things sorted today.

    1st thing to say is that NONE of the internal fuses had blown :confused: I thought I'd replace them anyway as I had already bought a new set.

    I then thought I'd check the fuse of the actual power plug, I opened the plug up and there was no visible sign of damage or of the fuse blowing, but I thought I'd change it anyway.

    Lo and behold, it powered up :D I think the new fuses I changed internally have also made some sort of improvement. The power on self test is a lot quicker and stable, and the whole system just seems to sound better for it.

    Anyway, it's a pleasure to finally have the system back up to full strength, I didn't realise how much I missed the extra control and impact it provided until I plugged it all back in, the improvement was instantaneous. In fact, it sounds better than I remember it, which kinda baffles me, surely a change of fuses all round couldn't squeeze out extra performance?

    Happy again, and the RB985 proves itself to be a winner again :). :D
     
  11. fama

    fama
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    Please would you clarify exactly what fuses you used and where to obtain
    them
    thanks
     
  12. Kazman

    Kazman
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  13. Smurfin

    Smurfin
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    Nice one Kaz:)
     
  14. Kazman

    Kazman
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    Cheers Smurfin :)

    Fama

    I just noticed you have the mkII, the fuse requirements may be different for that model as I have the mkI, not the mkII.

    Does anyone know the actual improvement the mkII has over the mkI?
     
  15. grafzep

    grafzep
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    I had a dead-on-one-channel RB991, opened it up and the internal fuses looked absolutely fine. However, I still checked them with a multimeter and found one was dead (tho not a mark on it). Replaced it and all was fine!
     
  16. Mark Ward

    Mark Ward
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    I had a dead channel on my RB985 MKII, turned out it was a short caused by the one of the rear phono connectors shorting. Apparantly they aren't that well constructed and this is a common fault. The repair wasn't cheap and I remember the engineer saying the internal layout was a pig to work on.

    Now fully repaired & sold so I can't check fuse location for you I'm afraid.

    From what I remember people saying at the time, the Caps inthe 985MKII are actually of a higher grade than those used in the RMB-1075 that superceded it.

    I do hope it's just a fuse.

    Mark.
     
  17. Kazman

    Kazman
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    Thanks for the advice dude. All sorted now though :) It was just a fuse, but the one in the plug rather than the internal ones, replaced all the internal fuses anyway, and the one in the plug, and now all is well :).

    I have the mkI rather than the mkII, I do like the look of the mkII, the mkI is a little bland to look at, but the power is wonderful :D
     
  18. fama

    fama
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    THANKS
    Yes I did note the difference.The only difference I can see in the specs
    is the quoted damping factor.It well just be cosmetic with the mk11 having large heat sinks.
     
  19. Kazman

    Kazman
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    AWESOME!!

    It sounds MUCH better than before, it's driving the speakers so well!

    I was watching House Of Wax last night, and the level of control has noticeably gone up a few notches. Great little Power Amp this :D :clap:
     
  20. Kazman

    Kazman
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    Ooer, after lots of good service, the 985 is creating a bit of Mains hum. Both channels.

    When the I take out the co-ax cables from the Pre-outs on the Marantz the hum dissappears.

    So I'm wondering if something is causing the hum on the Marantz or the Rotel. Was working fine for such a long time and now the hum is really taking the shine off what was a very well balanced system.

    Nothing has really changed in the setup, the hum just started out of nowhere. Anyone have any ideas before I start yanking out cables to check them out?
     
  21. eviljohn2

    eviljohn2
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    Check that all of your cables are seated properly - particularly the power leads. Sounds like a simple earthing issue. :)
     
  22. Kazman

    Kazman
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    Well, the hum goes away and comes back now, so somewhere in my system, something is causing feedback.

    I fear this is going to take an age to track down. Lots of fun :(
     
  23. Kazman

    Kazman
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    The hum was there constantly. So basically reverted back to biamping my front pair with the Marantz (means I use the two center rear channels but hey ho).

    I bought some quick blow fuses today as Maplins had run out of the slow blows. When speaking to one of the Rotel techies, they did mention that it could well be possible that the hum may be caused by one of the slow blow fuses on its way out.

    Will try to give the quick blow fuses a go tonight, thank goodness for banana plugs, makes moving cables round so much easier
     
  24. ChuckMountain

    ChuckMountain
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    Did you ever resolve this? I picked one up on the forums but only just got round to setting it up and I am getting a lot of hum.
     

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