Author Topic: Faulty GT64 Monitor  (Read 1233 times)

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Offline Audronic

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Faulty GT64 Monitor
« on: 23:49, 20 November 16 »
Hi All


I have a GT64 Monitor (Green Screen) that won't Power the 464 that it comes with.
The Monitor Works well if I power the 464 from an external Power supply.
Are there any component that regularly go faulty for me to look at as a starting point.
Or any hints or Tests to cary out.
Thanks     Ray

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Offline Audronic

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Re: Faulty GT64 Monitor
« Reply #1 on: 00:24, 21 November 16 »
Hi All
The fault has been resolved.


It turned out to be a "Dirty" Potentiometer R501 which gave me about 2.7 Volts initially.
After cleaning the pot it is now set to 5.01 Volts.
Ray
Photos below
Procrastinators Unite,
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I keep telling you I am Not Pedantic.
As I Live " Down Under " I Take my Gravity Tablets and Wear my Magnetic Boots to Keep me from Falling off.

Offline Audronic

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Re: Faulty GT64 Monitor
« Reply #2 on: 03:40, 21 November 16 »
Hi All

Arggggggg  I thought it was to easy ??

The + 5 Volt line sagged to about 2.74 Volts ( More Hair removed ).

BUT i remembered Bryce's comments a while ago about The Dreaded "" DRY  JOINTS "" .
So an inspection of the Board indicated that 7 of the Diodes had " Annular " rings around the Pins.
So Soldered them back with " FRESH " Solder, also some of the Heavy interconnecting leads also had suspect solder joints.
I hope that this is the end of this Project.
If anybody can find where R511 120 Ohm 2 Watt is located on the mother board as i cannot find it ??


Ray



Procrastinators Unite,
If it Ain't Broke PLEASE Don't Fix it.
I keep telling you I am Not Pedantic.
As I Live " Down Under " I Take my Gravity Tablets and Wear my Magnetic Boots to Keep me from Falling off.

Offline Bryce

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Re: Faulty GT64 Monitor
« Reply #3 on: 10:45, 21 November 16 »
R511 is beside the fuses and the plug from the transformer, between the row of rectifier diodes and capacitors. It's not hard to miss, it's a pretty big resistor.

Bryce.

Offline Audronic

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Re: Faulty GT64 Monitor
« Reply #4 on: 11:29, 21 November 16 »
Hi Bryce


Thanks i will have an other look it appears to be not where the layout diagram indicates.
Oh well another look.
Thanks    Ray
Procrastinators Unite,
If it Ain't Broke PLEASE Don't Fix it.
I keep telling you I am Not Pedantic.
As I Live " Down Under " I Take my Gravity Tablets and Wear my Magnetic Boots to Keep me from Falling off.

Offline ||C|-|E||

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Re: Faulty GT64 Monitor
« Reply #5 on: 11:39, 21 November 16 »
Now that you have the board out you can replace the caps and the thermal paste as well  :)

Offline Audronic

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Re: Faulty GT64 Monitor
« Reply #6 on: 11:47, 21 November 16 »
@||C|-|E||


Thanks I will have a look.


Ray
Procrastinators Unite,
If it Ain't Broke PLEASE Don't Fix it.
I keep telling you I am Not Pedantic.
As I Live " Down Under " I Take my Gravity Tablets and Wear my Magnetic Boots to Keep me from Falling off.