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Panther
March 4th, 2010, 04:29 AM
I've been given one of these, and have been told that the LOPT has gone, any ideas where I can get one of these in the UK? and are they difficult to replace ?

geoffm3
March 4th, 2010, 07:37 AM
They aren't hard to do, just be sure that all the HV is discharged before working on it and discharge the HV anode to the CRT of course.

It's a derivative of the Philips CM8833 according to this:

http://www.amiga-hardware.com/showhardware.cgi?HARDID=849

Found this with a google search, but boy is it pricey!

http://www.chsinteractive.co.uk/electrical-components/misc/cm8833-lopt-mod-kit.htm

geoffm3
March 4th, 2010, 07:38 AM
And of course, when I say care should be taken around the HV section, of course these voltages can be lethal! If the flyback is bad, these voltages may or may not be present, but it's best to act as if they are.

MikeS
March 4th, 2010, 08:21 AM
And of course, when I say care should be taken around the HV section, of course these voltages can be lethal! If the flyback is bad, these voltages may or may not be present, but it's best to act as if they are.Nasty but not usually lethal, especially if the flyback's really gone, but good advice nevertheless.
Some say that they're called flyback transformers over here is because that's what you do when you touch a working one, i.e. fly back across the room ;-)

I have three 1084s somewhere but have never looked at them to see if they work, or if not, what's wrong with them, but I suppose the OP can find one more easily and cheaply on his side of the pond anyway.

geoffm3
March 4th, 2010, 09:55 AM
Nasty but not usually lethal, especially if the flyback's really gone, but good advice nevertheless.
Some say that they're called flyback transformers over here is because that's what you do when you touch a working one, i.e. fly back across the room ;-)

I have three 1084s somewhere but have never looked at them to see if they work, or if not, what's wrong with them, but I suppose the OP can find one more easily and cheaply on his side of the pond anyway.

I always preferred the flyback terminology myself. Just sounds cooler than LOPT.

Agreed... usually it depends on how the voltage is applied to your person. :) It's usually way easier to shock yourself on the monitor chassis itself with the monitor powered up. Generally a wooden dowel makes a better pokey thing than your fingers when working on monitors.

Panther
March 9th, 2010, 05:44 AM
Will make sure I get some serious insulation before I crack it open then !!

That price for the LOPT and mod kit sounds way high !! will see what I can find and hopefully not shock myself across the room in the process !!

MikeS
March 9th, 2010, 08:23 AM
Will make sure I get some serious insulation before I crack it open then !!

That price for the LOPT and mod kit sounds way high !! will see what I can find and hopefully not shock myself across the room in the process !!
LOL! ;-)
I'd send you one of mine but it's probably not worth the shipping only to find out it's also dead. Hope you find someone over there with a broken monitor but a good LOPT.

nige the hippy
March 9th, 2010, 08:28 AM
1084 monitors seem to go for a song on ebay, it may not be worth repairing for any other reason than the "fun" of repairing it.
Regarding the EHT on the tube.
Get a lead with a crocodile clip at each end. clip one ond to the blade of a flat-blade screwdriver with an insulated handle, and clip the other to the metal chassis of the monitor. preferablty earth the metal chassis with something too, although it's not critical to do that.
Slide the metal blade of the screwdriver underneath the EHT cap on the tube until it contacts the metal contact (on a working machine there may be a "bang" here) do it 2 or 3 times to make sure.
Take hold of either side of the EHT cap, and squeeze it to disconnect the hooks that hook the contact into the CRT.
Lift it off.
Then touch the contact to the chassis, just to make sure.
Be careful on a working machine, as the CRT contact can be zappy too, even after disconnection (the crt itself has a fair amount of capacitance)