Toshiba LR27012 Zapping - I want to live again!

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lacanian
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Toshiba LR27012 Zapping - I want to live again!

Post by lacanian » December 30th, 2018, 12:57 am

So this is Christmas, and what have you done? Well I spent a few days getting my Astro City in perfect working order which included updating MAME, creating custom game lists and removing unsuitable games for kids. I thought I would introduce them all to some fun and simple games. Success! One final test before the kids arrive and zzzzaaaapp is all I hear from the Astro City. I walked away with my head down with no time to do more work on the Astro City.

It sounds like the zapping noise is coming from the yoke. Are there any basic troubleshooting steps I should look at? Would the monitor be fried or just the yoke? I have no idea where to start for the monitor and what actually may be dead.

Here is the deadly sound.
https://youtu.be/hE8roRjrGrU


Thanks.

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grantspain
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Re: Toshiba LR27012 Zapping - I want to live again!

Post by grantspain » December 30th, 2018, 12:21 pm

you need to remove the metal plate and see where the arcing is coming from, perhaps the anode cap has fallen off

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Retrob
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Re: Toshiba LR27012 Zapping - I want to live again!

Post by Retrob » December 30th, 2018, 5:38 pm

looks from that vid that the spark is coming from below the anode cap. Make sure you discharge the monitor before checking:

Is the anode cap on/in properly? Is there any dirt/grease/aquadag under the anode on the paint of the tube that could be conductive, causing it to arc?
Is the paint under the anode cup badly cracked/flaked off?

Edit: On looking again, it's hard to see, could it actually be coming from under the yoke? or it could even be a reflection onto the back of the tube from the neckboard?

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grantspain
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Re: Toshiba LR27012 Zapping - I want to live again!

Post by grantspain » December 30th, 2018, 7:06 pm

that is no normal HT tracking issue, that is either the tube fractured or direct HT to earth

lacanian
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Re: Toshiba LR27012 Zapping - I want to live again!

Post by lacanian » December 30th, 2018, 8:30 pm

Thanks everyone.

I will take it apart and discharge once the kiddies leave.

Can you explain what direct HT to earth means?

Thanks.

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grantspain
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Re: Toshiba LR27012 Zapping - I want to live again!

Post by grantspain » December 30th, 2018, 10:39 pm

means exactly that, the ht is directly connecting to an earth point/ metal work- would happen if the ht lead has come out of the anode or the flyback is cracked and is arcing to to the frame somewhere

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