GO7 F901

[Life is a Enigma]

Got a G07-CBO it keeps blowing f901 fuse I replace the horizontal transistor and fly back and it keeps blowing f901 any suggestions on where to look next? F902 is good. The original horizontal trends resistor tested good but replaced it anyways.It has a new cap kit in it from Arcade parts & repair and the caps are all in the right way.

 

[rod90]

http://lawnmowerman.rotheblog.com/rgvac/G07_Flowchart.jpg

Here is the flowchart.

 

[Life is a Enigma]

The flow chart is useless the two parts that says that could be bad are new and it's still blowing f901 fuse that's why I'm asking if there's something else I need to look at. As I said in my previous post I replaced the horizontal output transistor and I replaced the flyback with new parts and it still blowing f901 fues.

 

[ecwestjr]

Check all of the blue polypropylene capacitors located at C512, C513, C514, C531 and C532. If any of those are shorted it will cause F901 to blow. I've seen this a few times. Everything on these chassis are getting really old and a lot of different problems are starting to appear.

Ed

 

[ecwestjr]

Another part that can cause this also is C511. If it shorts it will blow the fuse. Since you did a cap kit it was replaced. However it isn't listed on the flowchart either.

So basically any part where one leg is connected directly to the B+ and the other leg is connected directly to ground if it shorts F901 is going to blow.

Ed

 

[thegleek]

The flow chart is useless the two parts that says that could be bad are new and it's still blowing f901 fuse that's why I'm asking if there's something else I need to look at. As I said in my previous post I replaced the horizontal output transistor and I replaced the flyback with new parts and it still blowing f901 fues.

someone else on this site posted this somewhere earlier on how to fix the infamous blowing F901 fuse!


EH wasn't very kind when they made the G07. Especially with X01 (HOT) and X04 (Power Regulator). Each one can be mounted in both directions.

1. Visually look at the way they are mounted. Pins for both should be centered, not closer to the lower edge.
2. Be sure you used mica insulators (or silicone) between the transistors and the frame along with the little white insulators in place correctly (I super glue them in place).
3. Make sure the wires are connected correctly.

Usually only 2 things cause F901 to blow:

• Shorted HOT (X01) - the emitter and collector should not have continuity
• Bad flyback transformer

A quick check for a shorted HOT is to set your meter to continuity/beeping test, place red meter lead on case of HOT and the black meter lead to the metal frame.
If your meter beeps, the HOT is bad. Be sure to check with the power off.

 

[Life is a Enigma]

Thanks guys for all your help I found the issue I did put a cap in backwards C511 fix that put a new fuse all is good except I need to replace the pods on the neckboard. I guess I get to wear the dunce cap on this one swearing up and down I had them all in right that's what I get for doing things too late too tired.

 

[Scott C]

Check all of the blue polypropylene capacitors located at C512, C513, C514, C531 and C532. If any of those are shorted it will cause F901 to blow. I've seen this a few times. Everything on these chassis are getting really old and a lot of different problems are starting to appear.

Ed

This is good information. To add to it, I recently fixed a G07 that kept blowing F901, despite having a good flyback and HOT (X01). Traced the issue back to the large cap on the neckboard, which is normally replaced as part of a cap kit (it was in backwards). After reversing it, F901 is stable and the monitor works as expected.

Scott C.

 

[RUSTINGEEZER]

I'm blowing F901 and am new to this so as usual this might be a stupid question.X01 is X901on the chart and board ? And when I do the ohm test with a meter to the case of transistor to frame I get .222 same as center leg is this a bad HOT?

 

[RUSTINGEEZER]

I'm blowing F901 and am new to this so as usual this might be a stupid question.X01 is X901on the chart and board ? And when I do the ohm test with a meter to the case of transistor to frame I get .222 same as center leg is this a bad HOT?

I tested the x901 on a working g07 unit and got various readings in the 15 , 9 ,11 k range ,different than the dead units .222 .im leaning towards bad hot replacement over replace the flyback .

 

[RUSTINGEEZER]

I tested the x901 on a working g07 unit and got various readings in the 15 , 9 ,11 k range ,different than the dead units .222 .im leaning towards bad hot replacement over replace the flyback .

also the .222 reading is with a popped fuse in circuit so I'm definitely putting in fuse clips and starting with the fuse intact to test it again ,and just order the flyback and some extras fuses and transistors anyway

 

[mecha]

be certain you're reinstalling the insulator behind the HOT/voltage regulator. back in the old days at my job now, where I would go for 17 hours a day, I was working on a G07 at probably 6 am and replaced the HOT and forgot the insulator. lol

otherwise Ed West and gleek provided a good checklist of things to check