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DXR15 AMP BOARD OFF

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Re: DXR15 AMP BOARD OFF

Postby Folderol » Mon Jan 13, 2020 10:00 am

gsc1ugs wrote:The 6.5v sorry fuse is on the main board of the dxr15 it did not blow, does that mean i dont have to check the bridge rectifier? Im just checking next the two capacitors next to the blown choke

If that fuse is on a 6.5V supply then it's not likely to be be relevant to the main bridge rectifier and smoothing electrolytic capacitor, both of which are possible suspects.
However, the damaged choke on the filter board, along with another one seem to have a rectangular block of metal inside them. Is this some kind of mechanical support? I'm still not entirely convinced there is nothing wrong with the board itself.

Also it's quite common to have a spike suppression varistor on input filters, and if they get more of a mains spike than they can handle, they can disintegrate quite dramatically. The usual 'remains' are a lot of flash residue and just a couple of wires sticking out of of the board seeming to go nowhere. is there anything like that there?

Finally, that flash damage is vaporised metal. It can be partly conductive so must be removed, otherwise it could cause another flashover.
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Re: DXR15 AMP BOARD OFF

Postby gsc1ugs » Mon Jan 13, 2020 10:12 am

Cant see any other visual damage, i'm waiting for my LCR meter then check two capacitors i will get back with my results. Thank you.
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Re: DXR15 AMP BOARD OFF

Postby gsc1ugs » Tue Jan 14, 2020 4:36 pm

Ok i spoke to yamaha who said its filtering the signal going out of the speaker to the mains, my question is this, in the picture avoiding the mains filtering, could i put 240v to the main board to see if it still comes on? the mains filtering board is #59 so not that bad but i want to see if the problem lies with the main board to pop the choke!! yamaha baffled has to why it blew.
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Re: DXR15 AMP BOARD OFF

Postby Folderol » Tue Jan 14, 2020 5:59 pm

Before attempting anything else, you should stick a meter on diode check across the terminals to make sure it's not shorting. Also do the same across the terminals of that big fat cap. This should appear short at first but will eventually so open as it charges up.

In the absence of a variac, see if you've got a 100W filament bulb somewhere, then put it in series with the live size before first attempting to power up. This will act as a current limiter, as well as showing you are drawing power. It should light up very brightly at first but rapidly fade down to an orange glow.
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Re: DXR15 AMP BOARD OFF

Postby Hugh Robjohns » Tue Jan 14, 2020 6:06 pm

I feel obliged to point out that working on live equipment can be lethal, and if you are not 100% certain and competent to do what you're trying to do, don't do it! Any work undertaken must be entirely at your own risk, any suggestions made by SOS forum members are not necessarily sanctioned or approved by SOS, and SOS does not accept any liability for any resulting damage or injury to equipment or persons....
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Re: DXR15 AMP BOARD OFF

Postby gsc1ugs » Tue Jan 14, 2020 6:23 pm

Ok, yamaha said to test i can bridge the L601 pins 1 to 2 & 3 to 4 to test, is it ok do this with 5 amp fuse wire? and i do take your point about safety Hugh
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Re: DXR15 AMP BOARD OFF

Postby James Perrett » Tue Jan 14, 2020 6:49 pm

Have you done the tests that Folderol suggested? Don't go any further until you have as you could otherwise blow something (or even someone) else up. If a capacitor that size is faulty it could fail very spectacularly.
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Re: DXR15 AMP BOARD OFF

Postby gsc1ugs » Tue Jan 14, 2020 7:02 pm

Folderol wrote:Before attempting anything else, you should stick a meter on diode check across the terminals to make sure it's not shorting. Also do the same across the terminals of that big fat cap. This should appear short at first but will eventually so open as it charges up.

In the absence of a variac, see if you've got a 100W filament bulb somewhere, then put it in series with the live size before first attempting to power up. This will act as a current limiter, as well as showing you are drawing power. It should light up very brightly at first but rapidly fade down to an orange glow.

big fat cap gives reading of 551 which diode you talking about>?
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Re: DXR15 AMP BOARD OFF

Postby Folderol » Tue Jan 14, 2020 7:18 pm

If that is stable, with the positive (red) of the meter on the positive (+) of the cap, and with the meter set to diode (or continuity or somesuch) then you have at least one rectifier somewhere faulty.
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Re: DXR15 AMP BOARD OFF

Postby gsc1ugs » Tue Jan 14, 2020 7:33 pm

So a reading of 551 is showing a fault on a rectifier?
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Re: DXR15 AMP BOARD OFF

Postby Bob Bickerton » Tue Jan 14, 2020 8:02 pm

Can’t help but reiterate what Hugh has said.

Unless you are a trained and ticketed technician, which given your line of questioning appears not (and no offence meant), then my advice would be to have someone qualified to fix this problem.

Two issues; firstly you could do more damage to the gear or yourself. Secondly, you may end up with a piece of gear that may fail again with potentially worse consequences - both of which could be detrimental to your career.

If you have public liability insurance (and everyone working in someone else’s venue should) it would likely be null and avoid if something happened.

Over here there are very tight rules around who can and can’t fix mains powered electrical equipment for commercial purposes.

At the end of the day, gear can fail (especially when dropped) and part and parcel of working with gear is an expectation to have to fix it and/or replace it. A hard reality, but one which has to be budgeted into your business plan.

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Re: DXR15 AMP BOARD OFF

Postby gsc1ugs » Wed Jan 29, 2020 5:33 pm

Just to put closure on this thread, noone knows why this coil blew but conjecture seems it was a spike in the electric, the mains filtering board filters not too the speaker but from the speaker back into the grid. The components one by one tested has they came off using 100w bulb to check for short. After thorough examination and replacement, no real culprit was found, short was there but vanished after replacement. Yamaha should improve the sub1 board by placing a fuse on it so it blows the circuit, dxr15 back in gigging, lets see how long we last.
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