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Monitor Isolation Power Identification
- Thread starter djsolzs
- Start date
It's a Ceramic resistor, and it's hot. That's normal. You can ohm across it and see if it matches the rating written on the side of it (or the print) and it's okay within 10-15%.
The next logical step is to get the cap kit and put it in and see how it acts then. If you want to shotgun it, go ahead and order a Hot and a flyback. It's only money LOL.
The next logical step is to get the cap kit and put it in and see how it acts then. If you want to shotgun it, go ahead and order a Hot and a flyback. It's only money LOL.
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OP
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Ill report back after the cap kit... I already got it... Thanks for the help!
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Got the chassis out... you can see in this pic how hot that side of the ceramic resistor is getting. Even a burn mark behind.
Could the new iso trans be overloading it? Or more likely a short on the chassis? i installed it per bob roberts diagram... if the wires were in wrong place? The ceramic is literally falling off...
Could the new iso trans be overloading it? Or more likely a short on the chassis? i installed it per bob roberts diagram... if the wires were in wrong place? The ceramic is literally falling off...
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that thing is toast it needs to bee replaced.
Peace
Buffett
Peace
Buffett
OP
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Just completed the cap kit... re-flowed some joints... yeah it looks really toasted. I guess I need to find out what actually toasted it... could it have been the iso tranformer? bad caps? would flyback do it?
I test the resistor and I get the appropriate ohms... but I definitely want to replace it.
Know where I can get one of these?
I test the resistor and I get the appropriate ohms... but I definitely want to replace it.
Know where I can get one of these?
I doubt if it was the iso transformer, it was dead. The caps can go bad in that circuit (looks like C810 & C807 went bad).
Bob doesn't have a 200ohm 15 watt resistor, only 10 watts. That's connected to Q801, the voltage regulator. If the resistor is burnt I wouldn't imagine that's transistor is in good shape. Its A 2SD777, that and those resistors and transistors are on ebay if nothing else. There is another transistor there, and a couple of diodes there on the first page of that schematic (I can't make out the p/n of that transistor) but it's probably not good either. You better check those diodes to see if they are okay. I had a problem with diodes recently in a 24V power supply. This is a 123V supply.
The flyback looks like an FS-57878, and it's high from Betson, like $50+. Did Bob have those?
Bob doesn't have a 200ohm 15 watt resistor, only 10 watts. That's connected to Q801, the voltage regulator. If the resistor is burnt I wouldn't imagine that's transistor is in good shape. Its A 2SD777, that and those resistors and transistors are on ebay if nothing else. There is another transistor there, and a couple of diodes there on the first page of that schematic (I can't make out the p/n of that transistor) but it's probably not good either. You better check those diodes to see if they are okay. I had a problem with diodes recently in a 24V power supply. This is a 123V supply.
The flyback looks like an FS-57878, and it's high from Betson, like $50+. Did Bob have those?
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KevinMullins
Active member
That's a dual spec resistor...200Ohm15watt on one side, 20Ohm 5 watt on the other.
Looks like the 20 Ohm side is what's getting toasted.
I'd check Q801 and see if it's shorted.
Also measure the AC input voltage going into the monitor.
To double check the isolation transformer....use the continuity test function on your meter and check from one side to the other. (input to output) There should be NO continuity.
Looks like the 20 Ohm side is what's getting toasted.
I'd check Q801 and see if it's shorted.
Also measure the AC input voltage going into the monitor.
To double check the isolation transformer....use the continuity test function on your meter and check from one side to the other. (input to output) There should be NO continuity.
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Thank you both for the great advice... thats exactly what I needed to continue to troubleshooting. I am learning how to read the schematics better.
So the voltage regulator (Q801) is a 2SD777.... correct? I will check that to see if its shorted... and the diodes in the area as well.
Thanks for chiming in kevin... I will do as you suggested as well and report back.
I keep searching online for the dual spec resistor... 200ohm 15 watt resistor... I am getting 200 Ohms on one side and 20 on the other when tested... where can I buy one of these?
So the voltage regulator (Q801) is a 2SD777.... correct? I will check that to see if its shorted... and the diodes in the area as well.
Thanks for chiming in kevin... I will do as you suggested as well and report back.
I keep searching online for the dual spec resistor... 200ohm 15 watt resistor... I am getting 200 Ohms on one side and 20 on the other when tested... where can I buy one of these?
KevinMullins
Active member
Yes.
You could get lucky and it will hold up for a while, since it appears to be in spec, but definitely keep looking for a replacement. Obviously finding the short or whatever is causing it to overheat is the key issue first.
Not sure where to find one like that. You may have to find two separate ones and wire them in series to match the original.
