CM8833-II Just died

General hardware issues and troubleshooting etc

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juz400
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Joined: Wed Sep 11, 2019 8:18 pm

Re: CM8833-II Just died

Post by juz400 »

Just make sure that the power is off when you short the HT cap to ground, its quite a scary spark if you dont! lol

It could also just be a dry joint around the HT transformer, if it gets bounced in shipping, hairline cracks in the copper tracks around the same area can be an issue.
Tomswork
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Re: CM8833-II Just died

Post by Tomswork »

Is there any high voltage noise from the horizontal output

Tom
terriblefire
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Re: CM8833-II Just died

Post by terriblefire »

juz400 wrote: Tue Oct 26, 2021 8:33 pm Just make sure that the power is off when you short the HT cap to ground, its quite a scary spark if you dont! lol
Yeah i already have an arc welder :D
juz400 wrote: Tue Oct 26, 2021 8:33 pm It could also just be a dry joint around the HT transformer, if it gets bounced in shipping, hairline cracks in the copper tracks around the same area can be an issue.
It was working for a while then stopped. I actually collected this one in person so i think it wasnt a transportation issue.
Tomswork wrote: Tue Oct 26, 2021 8:49 pm Is there any high voltage noise from the horizontal output

Tom
I've not opened it. I am still needing to make or preferably buy a discharge tool.
———
"It is not necessarily a supply voltage at no load, but the amount of current it can provide when touched that
indicates how much hurting you shall receive."
Danoo
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Re: CM8833-II Just died

Post by Danoo »

I have had to replace the flybacks on a variety of different monitors. I use a long screw driver with a lead attached to the shaft then insulated with heatshrink and electrical tape near the handle. Other lead end is a low ohm high watt resistor(arc reduction) and a alligator clip.

It is been a while since changing one in a 1084S, but if I remember correctly it is also worthwhile discharging the larger caps on the board with a resistor. I have had my fair share of heart shakers in my early years as a electrical / electronic technician, don't need a top-up. :roll:

As mentioned before, if the flyback is busted then the HOT will probably be near-on dead as well so changing both is good practice. :)

EDIT:
I always found tuning the screen and focus on the new flyback a more scary procedure then discharging the CRT, as the monitor is powered when tuning. :shock:
Life is really simple, but we insist on making it complicated - Confucius
mikro
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Re: CM8833-II Just died

Post by mikro »

Maybe my rejuvenation post can come in handy as an inspiration: https://www.atari-forum.com/viewtopic.php?f=15&t=38417 :)
Danoo
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Re: CM8833-II Just died

Post by Danoo »

Here is another POV on the dangers of CRT maintenance / repair, a interesting read https://lowendmac.com/2007/the-truth-ab ... ck-danger/
Life is really simple, but we insist on making it complicated - Confucius
terriblefire
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Re: CM8833-II Just died

Post by terriblefire »

Yeah i've had a few HV shocks over the years and my heart is fine. :)

I'd just like a premade tool rather than relying on my own handywork
———
"It is not necessarily a supply voltage at no load, but the amount of current it can provide when touched that
indicates how much hurting you shall receive."
terriblefire
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Re: CM8833-II Just died

Post by terriblefire »

I built me a discharge tool and removed the Anode cap without any drama. Just waiting for the replacement to arrive.

I dont have a replacement HOT on order so i guess i'm doing the flyback first.
———
"It is not necessarily a supply voltage at no load, but the amount of current it can provide when touched that
indicates how much hurting you shall receive."
terriblefire
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Re: CM8833-II Just died

Post by terriblefire »

Dismantled....
IMG_5568.jpeg
IMG_5568.jpeg (304.58 KiB) Viewed 2776 times
———
"It is not necessarily a supply voltage at no load, but the amount of current it can provide when touched that
indicates how much hurting you shall receive."
terriblefire
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Re: CM8833-II Just died

Post by terriblefire »

Finally got round to finishing this repair..
59B288E2-A085-47C3-BE7D-E4A0C118029C.jpeg
59B288E2-A085-47C3-BE7D-E4A0C118029C.jpeg (399.6 KiB) Viewed 2475 times
———
"It is not necessarily a supply voltage at no load, but the amount of current it can provide when touched that
indicates how much hurting you shall receive."
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