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Static Electricity fried my Yamama HS-80M Studio Monitors
Old 1 week ago
  #1
Gear Head
 

Thread Starter
Static Electricity fried my Yamama HS-80M

I blew an HS-80M this weekend. Get this, cleaning my studio, I got up from my chair, now granted, it's 0 degrees out, my home is very dry so some amount of static has been something I live with at this time of year, but regardless, I'm holding a metal goosneck mic (not plugged in to anything just the standard cheapo mic from a novation mininova). As i walk around the back of my desk, the xlr end of the mic touched the back of the speaker, on the fins that stick out near the top. Not near an input, or like inside the speaker or something, and not hard, literally an almost indiscernible tap, that immediately shorted something out in teh speaker. I heard the static zap transferring from my hand to the mic to the metal case of the speaker, then a thump and continuous loud hum from the speaker and immediately smelled electrical insulation or components burning. When I tried shutting it down and powering it back on, the speaker goes immediately to a loud, medium/low droning tone and pops the speaker all the way outwards. WTH!? Any thoughts on how this happened or how to repair are welcomed. I'm so bummed. As far as I know this should NEVER happen if it is designed correctly (ie. double insulated, or grounded/bonded metal chassis - Yes my ground is solid, 12AWG straight back to the main panel, all grounding is OK) The odds of something failing at the exact same time is just not likely: static electricity literally just fried my 350 dollar monitor. Yamaha will not do anything bout it. they don't even care to look at it to see how that's even possible unless I want to pay the shipping to California and the repair fees associated. Boo Yamaha! Super disappointed!
Old 1 week ago
  #2
Gear Maniac
 

Quote:
Originally Posted by proche3 View Post
I blew an HS-80M this weekend. Get this, cleaning my studio, I got up from my chair, now granted, it's 0 degrees out, my home is very dry so some amount of static has been something I live with at this time of year, but regardless, I'm holding a metal goosneck mic (not plugged in to anything just the standard cheapo mic from a novation mininova). As i walk around the back of my desk, the xlr end of the mic touched the back of the speaker, on the fins that stick out near the top. Not near an input, or like inside the speaker or something, and not hard, literally an almost indiscernible tap, that immediately shorted something out in teh speaker. I heard the static zap transferring from my hand to the mic to the metal case of the speaker, then a thump and continuous loud hum from the speaker and immediately smelled electrical insulation or components burning. When I tried shutting it down and powering it back on, the speaker goes immediately to a loud, medium/low droning tone and pops the speaker all the way outwards. WTH!? Any thoughts on how this happened or how to repair are welcomed. I'm so bummed. As far as I know this should NEVER happen if it is designed correctly (ie. double insulated, or grounded/bonded metal chassis - Yes my ground is solid, 12AWG straight back to the main panel, all grounding is OK) The odds of something failing at the exact same time is just not likely: static electricity literally just fried my 350 dollar monitor. Yamaha will not do anything bout it. they don't even care to look at it to see how that's even possible unless I want to pay the shipping to California and the repair fees associated. Boo Yamaha! Super disappointed!
That's really odd, according to the service manual which can be found here:
YAMAHA HS80M SERVICE MANUAL Pdf Download.

it's a class I appliance with PE connection.

Normally a heatsink which can be directly touched by anyone shouldn't cause problems when touched even when discharging ESD.

Maybe you should disconnect the speaker and tweeter and start troubleshooting.
Old 1 week ago
  #3
Gear Maniac
That is in fact very odd. I know from personal experience that static electricity can be very powerful sometimes. I've been zapped from 110 volt wall outlets, as well as a 400 volt guitar amp when I touched the wrong spot (it was only a 5 watt amp luckily), but the zap I got one day from spreading bed sheets down on a mattress was way worse. Point is, static electricity can get quite powerful.

The heat sink would be physically connected to the transistors inside the speakers amplifier, with some kind of glue. These transistors will look like a chip. It seems very unlikely, but not impossible, for the electricity to pass through the transistor and fry it on the inside. I'm sure there's more possibilities though.
Old 1 week ago
  #4
Gear Head
 

Thread Starter
Old 1 week ago
  #5
Gear Maniac
No, I don't think this is the same issue. The reason is because you said your speaker extrudes almost all the way out and stays there. That means it is being fed DC voltage, and therefore would most likely not be a power supply issue. That article you referenced does explain quite nicely how to check the power supply. If you get +15 volts, and -15 volts on the respective pins, then the power supply is working properly. Going back to my short in the transistor theory, if there was a short between the emitter and the collector, that would cause the speaker to push out, but there are a million other possible things that could be causing the problem. Often too, when one thing fails, it creates a chain reaction causing other components down the line to fail as well.
I would test the power supply, to make sure it is working properly. If it is (which I think it probably is), then just see if you can order a whole new circuit board from Yamaha, and install it yourself.
Old 1 week ago
  #6
Gear Head
 

Thread Starter
Thanks for the reply AO. So order a new Amplifier PCB with heatsink? I posted video of the issue. Eli (the guy who wrote the article above) seemed interested in knowing more so perhaps he can help me further troubleshoot once I open it up. I just need to know what happened, my engineering mind is running wild trying to make sense of this. No new speakers until taxes come in! :(

YouTube

As I open it up, I will post more
Old 1 week ago
  #7
Gear Maniac
Ya, it's sending a high amount of DC voltage directly to the speaker. Do not do this for more than a second or two, it will fry the speaker.
Yes, although I can't say for sure, but I think if you could get a new amplifier PCB this would probably solve your issue. You could still use your old heat sink, you just need the special glue for attaching it to the chip.
Old 1 week ago
  #8
Lives for gear
 
MarkF48's Avatar
I don't know what the OP's electronic skills are, but myself I'd likely replace both the output OpAmps for starters. The specs for the LM3886TF state pin 4, which is for the V(-) supply, is connected to heatsink tab. Impossible to know where a static discharge might track through, but the being connected even remotely through the output chip is suspicious.

"(1) The LM3886T package TA11B is a non-isolated package, setting the tab of the device and the heat sink at V− potential when the
LM3886 is directly mounted to the heat sink using only thermal compound. If a mica washer is used in addition to thermal compound,
θCS (case to sink) is increased, but the heat sink will be isolated from V−."


The LM3886TF isn't all that expensive a part as parts go...
LM3886TF Texas Instruments | Mouser

Heatsink grease would be used between the tab and the heatsink when reassembling.

Couldn't find the output board for the HS-80, but did find the input board.....
Yamaha WG266500 Input PCB for HS80M and HS50M | Full Compass
I reckon the output board will be substantially more in cost, to the point of might just as well buy a new monitor. Yamaha parts department could likely give a price for part number 'WG266400' Output PCB.
I've bought parts from Yamaha a while back.
Yamaha
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