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12 July 2015, 22:55
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#1 |
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Registered User
Join Date: Apr 2010
Location: Italy
Posts: 1,136
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problem with rf and composite on a1200 rev 1d4
i have 2 mainboard whit this problem, i changed caps, changed cxa1145 with new, but nothing
on one board i have changed delay line, verify connection, but nothing any idea? |
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13 July 2015, 16:24
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#2 |
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Registered User
Join Date: Feb 2014
Location: Maitland / AUSTRALIA
Posts: 205
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Assuming you have correct RGB output?
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13 July 2015, 22:53
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#3 |
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Registered User
Join Date: Apr 2010
Location: Italy
Posts: 1,136
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sure
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14 July 2015, 00:39
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#4 |
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Registered User
Join Date: May 2006
Location: Kilmacolm
Age: 46
Posts: 632
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What's the trouble exactly? Just black screen?
Can your receiver tune in to the rf, (audio? even if only displaying black)? I suggest checking carefully that circuits to pin 13 and 14 of cxa1145 are correct. Sorry I can't remember what the reference voltage should be, compare with a working board if you can. Also verify CSYNC trace from pin 4 of U23 to pin 10 of cxa1145. Got a scope? |
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14 July 2015, 09:55
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#5 |
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Registered User
Join Date: Apr 2010
Location: Italy
Posts: 1,136
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from composite no signal
the receiver don't tune auto, manual i have a black screen with white line the scope is very old go to compare with other board update changed z222 and one work fine Last edited by cpiac64; 14 July 2015 at 11:26. |
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15 July 2015, 00:35
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#6 |
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Registered User
Join Date: May 2006
Location: Kilmacolm
Age: 46
Posts: 632
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Old scope is fine if it can show a trace, precise measurements are not required, just need to verify that colour, sync and oscillator signals are getting where they are meant to.
You can test Z221 and Z222 in circuit by simply shorting them out, (careful, not from the pins of the chip but from the terminals of the supporting components). If they are faulty, bypassing them should allow the video signal to display although with colour faults. |
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03 February 2017, 12:49
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#7 |
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Registered User
Join Date: Apr 2010
Location: Italy
Posts: 1,136
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today i have time for inspection, found c222 break, changed with new and now all ok
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