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bluemoonhu
Joined: 16 Feb 2021
Posts: 259
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| Posted: Tue May 31, 2022 4:10 am Post subject: Barco 708MM “HOLD DOWN EHT” fault |
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the measurement of SR70 is the same as the resistance beside it
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Hulio
Joined: 15 Apr 2006
Posts: 494
Location: Belgium
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| Posted: Tue May 31, 2022 6:03 am Post subject: |
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Ok, those fusible resistors are good. Now check the HV fuses (two right behind the front left fan), the standby fuse beside the upper brown trafo and all 10 surface mounted fuses in the middle of the board. Just flip the power supply and test them on the underside of the PCB.
No beep sound on your multimeter, the fuse is blown.
Than we go further with more tests, you have to wait for that capacitor, anyway....
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bluemoonhu
Joined: 16 Feb 2021
Posts: 259
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| Posted: Tue May 31, 2022 6:26 am Post subject: Barco 708MM “HOLD DOWN EHT” fault |
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The fuse in the picture is broken, and other fuses are intact。
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Hulio
Joined: 15 Apr 2006
Posts: 494
Location: Belgium
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| Posted: Tue May 31, 2022 7:03 am Post subject: |
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Alright, that is the F13 fuse (4Ah) responable for the 9V supply. Should be changed too.
To be sure is broken, you can measure at the upper side of coil L23 (but for this, you should solder back that capacitor). No 9V on coil L23 = fuse F13 is blown.
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bluemoonhu
Joined: 16 Feb 2021
Posts: 259
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| Posted: Tue May 31, 2022 7:35 am Post subject: |
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wait that capacitor....
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Hulio
Joined: 15 Apr 2006
Posts: 494
Location: Belgium
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| Posted: Tue May 31, 2022 7:53 am Post subject: |
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C45 you just removed yesterday...
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bluemoonhu
Joined: 16 Feb 2021
Posts: 259
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| Posted: Tue May 31, 2022 9:12 am Post subject: |
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| Hulio wrote: | | C45 you just removed yesterday... |
I don't know if it's good or bad。 so,I bought some new ones.
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Hulio
Joined: 15 Apr 2006
Posts: 494
Location: Belgium
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| Posted: Tue May 31, 2022 10:24 am Post subject: |
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Yeah, I know Hu. It was just to see if you get 9V at the top of coil L23. A capacitor with lower than rated capacity is better than a interrupted circuit.
But don't worry, if no continuity on fuse F13, means broken. Change that too.
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bluemoonhu
Joined: 16 Feb 2021
Posts: 259
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| Posted: Tue May 31, 2022 11:49 am Post subject: |
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| Hulio wrote: | Yeah, I know Hu. It was just to see if you get 9V at the top of coil L23. A capacitor with lower than rated capacity is better than a interrupted circuit.
But don't worry, if no continuity on fuse F13, means broken. Change that too. |
You mean, I don't wait for the new capacitor to come back，and reinstall the removed capacitor and test whether the L23 voltage is 9V?
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Hulio
Joined: 15 Apr 2006
Posts: 494
Location: Belgium
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| Posted: Tue May 31, 2022 12:17 pm Post subject: |
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Yes, that's what I meant. And because you did not test the capacitance of that capacitor (uF), it could be that is still good.
Also, you can "borrow" F13 fuse from your Vision 708, if you wish.
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bluemoonhu
Joined: 16 Feb 2021
Posts: 259
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| Posted: Tue May 31, 2022 12:36 pm Post subject: |
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| Hulio wrote: | Yes, that's what I meant. And because you did not test the capacitance of that capacitor (uF), it could be that is still good.
Also, you can "borrow" F13 fuse from your Vision 708, if you wish. |
let me try
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bluemoonhu
Joined: 16 Feb 2021
Posts: 259
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| Posted: Tue May 31, 2022 1:15 pm Post subject: |
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F13 fuse was removed， it's really broken.
If its upper level is broken, even if a good fuse is replaced, it will burn out。
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Hulio
Joined: 15 Apr 2006
Posts: 494
Location: Belgium
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| Posted: Tue May 31, 2022 1:29 pm Post subject: |
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Yes, could be. But than we know for sure the problem is somewhere else in the circuit. A fuse can blow even because a connector was misplaced by one pin (previous owner ??).
And a fuse cost few cents....Worth to try.
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bluemoonhu
Joined: 16 Feb 2021
Posts: 259
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| Posted: Tue May 31, 2022 3:14 pm Post subject: |
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I have bought the F13 fuse, and will install it after two days....
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Hulio
Joined: 15 Apr 2006
Posts: 494
Location: Belgium
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| Posted: Tue May 31, 2022 3:52 pm Post subject: |
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👍
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bluemoonhu
Joined: 16 Feb 2021
Posts: 259
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| Posted: Fri Jun 03, 2022 2:28 pm Post subject: |
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C45 is good and reinstalled, the F13 was replaced by a new fuse，but it was burned after starting the C7. Obviously, another part failed。
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Hulio
Joined: 15 Apr 2006
Posts: 494
Location: Belgium
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| Posted: Fri Jun 03, 2022 4:07 pm Post subject: |
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Alright, it means that one (or more) of the following components could be burned:
Voltage rectifier D37 (MBR1045)
Ceramic capacitor C81 (4700 uF 63V)
Electrolytic capacitor C82 (2200 uF 16V
Close to those fuses (where F13 is locates), you have a heat sink with several transistors mounted on. D37 is second from below, on the right side of the heat sink. C81 and C82 are mounted in close proximity of D37.
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bluemoonhu
Joined: 16 Feb 2021
Posts: 259
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| Posted: Sat Jun 04, 2022 12:23 am Post subject: Barco 708MM “HOLD DOWN EHT” fault |
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D37[/u]
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bluemoonhu
Joined: 16 Feb 2021
Posts: 259
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| Posted: Sat Jun 04, 2022 12:25 am Post subject: |
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D37 abnormal，C81 and C82 normal。
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bluemoonhu
Joined: 16 Feb 2021
Posts: 259
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| Posted: Sat Jun 04, 2022 12:29 am Post subject: |
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Except D37， will other voltage rectifier fail?
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