Author Topic: Question on CTM644 - Very dark picture  (Read 6318 times)

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Offline CanonMan

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Re: Question on CTM644 - Very dark picture
« Reply #25 on: 15:27, 13 March 15 »
whats wrong with that method?


What's right with it? Think about it...  :laugh:

Offline roy bates

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Re: Question on CTM644 - Very dark picture
« Reply #26 on: 15:41, 13 March 15 »

What's right with it? Think about it...  :laugh:


i did think about it,lol...so would you like to explain?

Offline Bryce

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Re: Question on CTM644 - Very dark picture
« Reply #27 on: 15:53, 13 March 15 »
If you use a "bare" screwdriver like this one: http://www.hubertuy.com/wp-content/uploads/2015/02/screwdriver.png
Then there's a good chance that the voltage will arc to your hand. Not good.
Better to use an electricians (insulated) screwdriver: http://www.hyperclaw.com/pic/products/vde_philips_screwdriver_L.jpg
But even then... If a jobs worth doing, it's worth doing properly. And proper jobs are done with proper tools.

Bryce.



Offline The Last Bandit

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Re: Question on CTM644 - Very dark picture
« Reply #28 on: 17:44, 13 March 15 »
You're better off with a flat blade, those philips/posi are a bugger to get under the anode cap  :D


Shielded long screwdriver, bit of wire and a croc clip has served be well on a variety of TV & monitors. 22KV seems a bit high for the CTM644 though, my 19" arcade crt  is about that. General rule of thumb is approx 1KV per inch plus a few KV.
[size=78%]  [/size]

Offline roy bates

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Re: Question on CTM644 - Very dark picture
« Reply #29 on: 18:43, 13 March 15 »
a 14 inch crt's yields about 15kv.




Offline ivarf

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Re: Question on CTM644 - Very dark picture
« Reply #30 on: 23:55, 13 March 15 »
The knobs on the back off a CTM644 are to adjust V-Hold and H-Hold. They will not have any effect on the brightness of the picture and due to their age, only turn them if you really have to
Did they remove  the brightness pot from the back of later models? The 464 colour monitor had it

Offline pelrun

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Re: Question on CTM644 - Very dark picture
« Reply #31 on: 06:53, 14 March 15 »
The external brightness pot for a CTM644 is on the right side, not the back. But it's limited (you don't want the consumer burning out the tube!) and requires the internal sub-brightness pot to be adjusted properly.

Offline ivarf

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Re: Question on CTM644 - Very dark picture
« Reply #32 on: 09:56, 14 March 15 »
I remember one at the back as well. It might have been a hole in the case where you had access to the potmeter with a screwdriver

Offline Bryce

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Re: Question on CTM644 - Very dark picture
« Reply #33 on: 18:45, 14 March 15 »
@Canonman: Of course a flat head would be used. My example was just to show the type of insulation.

@Roy: 15KV hurts too :D

Bryce.

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Offline roy bates

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Re: Question on CTM644 - Very dark picture
« Reply #34 on: 19:59, 14 March 15 »
 :laugh: bryce, ;D 15kv will more than hurt mate.

Offline kevin.c

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Re: Question on CTM644 - Very dark picture
« Reply #35 on: 21:21, 14 March 15 »
Thanks God, discharging the LCD is much more safe.

Offline roy bates

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Re: Question on CTM644 - Very dark picture
« Reply #36 on: 00:18, 15 March 15 »
i like working on crt's so i dont really worry about it myself :laugh:

i would rather have a crt than a lcd for sure..especially on older machines like cpc's