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Barco 708MM “HOLD DOWN EHT” fault
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Hulio




Joined: 15 Apr 2006
Posts: 469
Location: Belgium


PostLink    Posted: Tue Jun 21, 2022 2:35 pm    Post subject: Reply with quote


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That's the horizontal linearity control board, and there is no component C7 on it. I think you are confusing it with the electrolytic capacitor C1.
Q1 is the one in your picture, that's a MOSFET transistor and to check it out you have to take it out of the circuit.
From left to right in your picture, the transistor legs are: Gate, Drain, Source. The best way to check it, is to put your multimeter in diode modus.
Black probe to Source and red probe to Drain should give a reading between 0,4V and 0,9V. If 0, open or no reading, the transistor is bad.
Now if you reverse the probes (black probe to Drain and red probe to Source) and the reading is 0, open, or no reading, the transistor is also bad.
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bluemoonhu




Joined: 16 Feb 2021
Posts: 228



PostLink    Posted: Wed Jun 22, 2022 2:59 am    Post subject: Reply with quote

Hulio wrote:
That's the horizontal linearity control board, and there is no component C7 on it. I think you are confusing it with the electrolytic capacitor C1.
Q1 is the one in your picture, that's a MOSFET transistor and to check it out you have to take it out of the circuit.
From left to right in your picture, the transistor legs are: Gate, Drain, Source. The best way to check it, is to put your multimeter in diode modus.
Black probe to Source and red probe to Drain should give a reading between 0,4V and 0,9V. If 0, open or no reading, the transistor is bad.
Now if you reverse the probes (black probe to Drain and red probe to Source) and the reading is 0, open, or no reading, the transistor is also bad.


OK!
I wonder why the deflection board was burned? first deflection board of C7, then deflection board of 708.... Is it the SMPS board or the focus board or other reasons?
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bluemoonhu




Joined: 16 Feb 2021
Posts: 228



PostLink    Posted: Wed Jun 22, 2022 3:03 am    Post subject: Reply with quote

If the cause is not found, even if the deflection board is replaced with a good board, it will burn again.
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bluemoonhu




Joined: 16 Feb 2021
Posts: 228



PostLink    Posted: Fri Jun 24, 2022 2:32 am    Post subject: Barco 708MM “HOLD DOWN EHT” fault Reply with quote

The measured value of one triode on the deflection board is different with the other two.[/i]


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bluemoonhu




Joined: 16 Feb 2021
Posts: 228



PostLink    Posted: Fri Jun 24, 2022 2:37 am    Post subject: Barco 708MM “HOLD DOWN EHT” fault Reply with quote

It's going to be removed and tested


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Hulio




Joined: 15 Apr 2006
Posts: 469
Location: Belgium


PostLink    Posted: Fri Jun 24, 2022 4:46 am    Post subject: Reply with quote

That's not thyristor C7 but high voltage MOSFET (transistor) Q10.
You can check it the same way as above if you wish, but i doubt it is broken. It is normal to give other reading than Q8 and Q9, as long time the components are not measured out of the circuit.
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bluemoonhu




Joined: 16 Feb 2021
Posts: 228



PostLink    Posted: Fri Jun 24, 2022 5:07 am    Post subject: Reply with quote

oh,sorry! C7 means Barco Cine7.

Thanks!
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bluemoonhu




Joined: 16 Feb 2021
Posts: 228



PostLink    Posted: Fri Jun 24, 2022 5:17 am    Post subject: Barco 708MM “HOLD DOWN EHT” fault Reply with quote

Hulio wrote:
That's not thyristor C7 but high voltage MOSFET (transistor) Q10.
You can check it the same way as above if you wish, but i doubt it is broken. It is normal to give other reading than Q8 and Q9, as long time the components are not measured out of the circuit.


OK, if Q10 is broken, I will replace it. I have bought Q10 and it is on the way,thank you!
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bluemoonhu




Joined: 16 Feb 2021
Posts: 228



PostLink    Posted: Fri Jul 29, 2022 1:42 pm    Post subject: Reply with quote

I come back and continue to talk about this C7. after changing some boards, C7 was finally lit, However, it brings a new problem. Using this connection method: pioneer 09fd-hdmi-moone-5bnc-5bnc-c7, the signal source is set to 3, and the displayed image is very dark. It is found that the contrast adjustment of the image is invalid, but the brightness adjustment is normal. I can't find the reason. thank you!
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bluemoonhu




Joined: 16 Feb 2021
Posts: 228



PostLink    Posted: Fri Jul 29, 2022 1:51 pm    Post subject: Barco 708MM “HOLD DOWN EHT” fault Reply with quote

The brightness of the image is low. Because the contrast adjustment fails, the contrast of the image cannot be increased to improve the brightness, so it cannot be viewed normally


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bluemoonhu




Joined: 16 Feb 2021
Posts: 228



PostLink    Posted: Sat Jul 30, 2022 2:41 pm    Post subject: Reply with quote

I replaced the GBR board of this C7, and the contrast adjustment function returned to normal
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bluemoonhu




Joined: 16 Feb 2021
Posts: 228



PostLink    Posted: Sat Jul 30, 2022 2:44 pm    Post subject: Barco 708MM “HOLD DOWN EHT” fault Reply with quote

You can see the words "contrast adjustment" on the GBR board


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Hulio




Joined: 15 Apr 2006
Posts: 469
Location: Belgium


PostLink    Posted: Sat Jul 30, 2022 9:58 pm    Post subject: Reply with quote

No contrast adjustments on the RGB input board. The text "To contrast mudulation" next to connector J757 means you can connect the optional contrast modulation board R7624845 in there. Something you don't need.
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bluemoonhu




Joined: 16 Feb 2021
Posts: 228



PostLink    Posted: Sat Jul 30, 2022 11:20 pm    Post subject: Barco 708MM “HOLD DOWN EHT” fault Reply with quote

Hulio wrote:
No contrast adjustments on the RGB input board. The text "To contrast mudulation" next to connector J757 means you can connect the optional contrast modulation board R7624845 in there. Something you don't need.


You're right!
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bluemoonhu




Joined: 16 Feb 2021
Posts: 228



PostLink    Posted: Sun Jul 31, 2022 12:29 am    Post subject: Barco 708MM “HOLD DOWN EHT” fault Reply with quote

Can you find the contrast adjustment module or circuit unit in the GBR board?Can it be repaired?


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