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Old 04-28-2018, 05:31 PM   #1
John843883
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Default Toshiba 42AV635D arcing/sparking noise when power switch is turned one (sometimes)

Hi, has anyone come across this before and is it a known issue? Its the actual hard power switch on the side of the set which triggers the noise and I've been told it only happens sometimes when switched on from being off for a while. When it happens my relatives switch it off quick but cycling it does get it to go away eventually and the TV works from then on.

Having heard the noise in person it does sound like arcing/popping and obviously this is a bit of a fire risk so I plan on fixing it but just wanted to see if anyone else has seen this before.

The red standby light does come on whilst its making this noise but we've not tried to turn it on during the sparking in-case the extra load trips whenever is making the noise over the edge. I guess it could be the power switch still as the standby supply is probably low power and tolerant to fluctuations in supply voltage.

I've not had the back off yet so can't rule out anything else at this stage (cracked solder joints etc).

tl;dr I suspect the hard power switch on a Toshiba REGZA 42AV635D is arcing, has anyone heard of this problem before?

Thanks.

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Old 04-28-2018, 05:41 PM   #2
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Default Re: Toshiba 42AV635D arcing/sparking noise when power switch is turned one (sometimes

If it's the rocker switch underneath, I replaced one that was crackling/arching last week.
It was an internal failure of the switch.
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Old 04-28-2018, 05:47 PM   #3
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Default Re: Toshiba 42AV635D arcing/sparking noise when power switch is turned one (sometimes

Quote:
Originally Posted by diif View Post
If it's the rocker switch underneath, I replaced one that was crackling/arching last week.
It was an internal failure of the switch.
Thanks! I haven't opened it up yet but from shining a flashlight inside it looks a lot like this one. It feels like a latching press switch (if that makes sense). Looking at the screen face on its on the left hand side toward the bottom of the unit tucked away behind the screen bezel.

If it was like this did you just buy a replacement from Ebay or was you able to find the switch from somewhere like RS Components etc?

Full model is actually Toshiba REGZA 42AV635D
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Old 04-28-2018, 05:55 PM   #4
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Default Re: Toshiba 42AV635D arcing/sparking noise when power switch is turned one (sometimes

It was a rocker switch on the one I replaced, a common style I have in stock.
Could just be a dry joint/s if it's one of those type of switch.
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Old 04-29-2018, 04:21 AM   #5
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Default Re: Toshiba 42AV635D arcing/sparking noise when power switch is turned one (sometimes

Update: The power switch is indeed bad, the PSU has a big 220uF input filter capacitor so maybe the inrush from that just wears the switch out after several years (even with all the inrush limiting).

Is it acceptable to use ebay as a source for a new mains switch? Replacements are pretty cheap on there and readily available, will have a look on the more trusted suppliers like RS components, farnell, rapid etc but just googling the part number "kdc-a02-f 5a/80a/250v" doesn't return any results from the regular go-to suppliers.

Looks like it must be a common issue if these switches are so readily available on ebay and amazon listed as Toshiba replacements.
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Old 04-29-2018, 04:36 AM   #6
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Default Re: Toshiba 42AV635D arcing/sparking noise when power switch is turned one (sometimes

Ebay will be fine, it doesn't look like a common switch.
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Old 04-29-2018, 04:50 AM   #7
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Default Re: Toshiba 42AV635D arcing/sparking noise when power switch is turned one (sometimes

If you have trouble finding a replacement board then contact me via email. I have the identical board including switch (but not the button) in my collection of spare parts for sale.
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Old 04-29-2018, 06:31 AM   #8
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Default Re: Toshiba 42AV635D arcing/sparking noise when power switch is turned one (sometimes

Its a common fault. Just get switch from Ebay but be carefull with the plastic button as thats not so easily replaced or found
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Old 04-30-2018, 01:41 AM   #9
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Default Re: Toshiba 42AV635D arcing/sparking noise when power switch is turned one (sometimes

Quote:
Originally Posted by diif View Post
Ebay will be fine, it doesn't look like a common switch.
Thanks. Also I came across a cross reference for this switch which lists equivalent part numbers so that may be useful to anyone who stumbles across this thread. https://www.donberg.co.uk/descript/s/sw_773.htm

Quote:
Originally Posted by dick_barton View Post
If you have trouble finding a replacement board then contact me via email. I have the identical board including switch (but not the button) in my collection of spare parts for sale.
Thanks for the offer, I really appreciate it! However I'm leaning toward a new switch at this point as wouldn't a used one be subject to the same wear and tear which caused mine to fail? If I mess up putting the new one in and this offer is still open then I'll get back to you if that's ok.

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Originally Posted by sintv View Post
Its a common fault. Just get switch from Ebay but be carefull with the plastic button as thats not so easily replaced or found
I've taken note of that. Funny, I came across a guy on youtube who resorted to using a piece of folded paper when his plastic bit got worn down https://www.youtube.com/watch?v=LVKDMo3Sbtk .

So you've seen this arcing switch problem before? Is it just the bigger TV's with larger input filter capacitors that suffer or do the smaller ones fail too?

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Old 04-30-2018, 06:45 AM   #10
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Default Re: Toshiba 42AV635D arcing/sparking noise when power switch is turned one (sometimes

You can go ahead and replace the switch with any fast acting AC switch, single throw, single pole.
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Old 04-30-2018, 07:05 AM   #11
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Default Re: Toshiba 42AV635D arcing/sparking noise when power switch is turned one (sometimes

I would just bypass the switch not needed
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Old 04-30-2018, 07:54 AM   #12
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Default Re: Toshiba 42AV635D arcing/sparking noise when power switch is turned one (sometimes

Quote:
Originally Posted by Andrew F. Ali View Post
You can go ahead and replace the switch with any fast acting AC switch, single throw, single pole.
I had a look in my parts box but nothing I have appears to line up, plus there's an extra plastic plunger thing on the main chassis which pushes this switch down so probably needs to be this exact style.

Quote:
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I would just bypass the switch not needed
I suggested this to my relative but they said they preferred having a real power switch, and to be fair I have seen the power consumption on the smart meter drop by about 20w when this TV was turned off from standby. The product sheet states 0.7w standby power so I'm not sure what the deal is, do these things have a mini operating system that takes a while to shut down when standby mode is activated?

The new switch is on the way so I'll update this thread once it arrives.
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Old 05-01-2018, 05:37 AM   #13
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Default Re: Toshiba 42AV635D arcing/sparking noise when power switch is turned one (sometimes

Ok so the switch arrived and I soldered it to the board, the bottom solder joints look ok but I forgot to flux up the top side and have ended with questionable joints on the top side. I soldered it from the bottom track side and the solder traveled down the holes.

Is it ok to leave the top side looking like this or will it cause cracking problems later on? The PCB holes had little metal inserts and the switch clicked into place well and didn't move much, but I'm not sure how the mechanical stresses will transfer.

Should I try and correct this or am I likely to mess the switch up by trying to get the perfect solder joint on both sides?
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Old 05-01-2018, 08:33 AM   #14
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Default Re: Toshiba 42AV635D arcing/sparking noise when power switch is turned one (sometimes

That looks fine. It will work like that. Time to close up this TV. Good luck.
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Old 05-01-2018, 09:56 AM   #15
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Default Re: Toshiba 42AV635D arcing/sparking noise when power switch is turned one (sometimes

Well I couldn't leave things alone and decided to try and make the topside joints better, I removed some of the excess solder and coated the legs with the RMA flux pen then added a little fresh solder. It appears to have wicked up the legs much better now although I still think there's too much on the right leg

OCD is one hell of a drug!

Also this is what the inside of the failed sparking switch looks like, kind of feels like the shaft lubricant has worked its way down into the contact area and semi-insulated it.

I'll update this thread again when I put the board back in (probably later in the week). This stuff is pretty mundane to seasoned repair techs but for people like me stumbling upon this thread its nice to get the all clear that the appliance was fixed using this method.
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Old 05-01-2018, 10:12 AM   #16
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Default Re: Toshiba 42AV635D arcing/sparking noise when power switch is turned one (sometimes

What does it say on the switch?
I see GCG, XXX80A 250V
It looks like the switch cannot handle the inrush current and no snubber.
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Old 05-01-2018, 10:20 AM   #17
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Default Re: Toshiba 42AV635D arcing/sparking noise when power switch is turned one (sometimes

Quote:
Originally Posted by budm View Post
What does it say on the switch?
I see GCG, XXX80A 250V
It looks like the switch cannot handle the inrush current and no snubber.
"CGC 5A/80A/250~" those ratings are the same as the Toshiba original switch. There is a space on the board for a bypass jumper but maybe I could put a small capacitor across it? Or would that cause ghost voltages to flick the TV in and out of standby? I looked at the specs for the TV and they claim 0.7w standby power.

I guess if it blows again I'll just bypass it for good but for now I'll recommend leaving the TV in standby if possible.

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Old 05-01-2018, 10:39 AM   #18
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Default Re: Toshiba 42AV635D arcing/sparking noise when power switch is turned one (sometimes

You can use something like this:
https://www.mouser.com/ProductDetail...SABEgLsO_D_BwE
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Old 05-01-2018, 11:13 AM   #19
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Default Re: Toshiba 42AV635D arcing/sparking noise when power switch is turned one (sometimes

Quote:
Originally Posted by budm View Post
Interesting, didn't know they made snubbers in one package. Any idea what RC values would be best suited toward 240v(occasionally 250v) mains? I know the resistor in this arrangement can heat up quite a bit.
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Old 05-01-2018, 11:29 AM   #20
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Default Re: Toshiba 42AV635D arcing/sparking noise when power switch is turned one (sometimes

The value you see is typical 22 Ohms in series with 0.1uF cap. You can calculate the power dissipation of the resistor, but since this one is already made for up 600V so not to worry.
This kind of RD snubber package has been around for years.
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