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Old 29th December 2012, 08:41 PM   #31
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Check the voltage at the input of the transformer T451. You need to have AC voltage to be able to energize the relays.
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Old 29th December 2012, 08:46 PM   #32
srinath is offline srinath  United States
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t451 lights up the led in front, and gives me 5.5v etc, its working, it also gets warm.
I am thinking I'll wire the relays, I suspect the display board has a bad sony cx somehting chip.
Cool.
Srinath.
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Old 29th December 2012, 09:01 PM   #33
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Hi,
What it is the voltage at the fuse FC454?
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Old 29th December 2012, 10:28 PM   #34
srinath is offline srinath  United States
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I will try that tomorow, I have the amp apart now, all the 8 fuses in the main board have been checked and are all good. I will get back to it tomorow.
Cool.
Srinath.
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Old 29th December 2012, 10:56 PM   #35
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Hi,
No problem. When you have it together please check voltage at Pin 1,2,4 and write down the voltage.
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Old 29th December 2012, 11:31 PM   #36
srinath is offline srinath  United States
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On cp458 I have done that, 1 was 0 vdc, 2 was 2.82 vdc, and 4 was like 5.5 vdc. In standby mode. Wont power on to be able to get it in the on stage. Pin 5 was 0 as well, that 30v for it has to come from the main transformer.

That pin is fed by the front board where when you put on the tact switch. It needs that cxp82860 IC to send it voltage - or like close/open something that lets it get power. That isn't happening and I think that chip has got a glitch and isn't taking the command from the tact switch. I am sadly unable to reset it as well, and I cant remove and replace the chip either, it is too small and sort of made into the board.

Anyway I have been modifying the thing to let me pull different boards off without pulling the whole thing apart. Anyway I'll check those voltages and put it on here.
Cool.
Srinath.
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Old 29th December 2012, 11:51 PM   #37
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Hi,
Okay then pin 2 need to be 3.5 volt or higher so the micro see it that the power it is on. the reading of 2.8 volt it is marginal and it is possible that the micro it is thinking the power it is down. I was looking for the specs of D458 UZ5V1 but I can not find it. I think it is a 5 volt diode but I do not know if it is true. I think the output should be 5 volts.
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Old 29th December 2012, 11:59 PM   #38
srinath is offline srinath  United States
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OK pin 2 voltage being low could mean I dont have a fully working T451 - transformer right ?
Or any of those diode bridge components ? or a burnt out D458UZ5V1 ? Is that your suspicion ?

man you are so cool, thanks so much for helping me out, that diode I can buy and swap it and see if it helps.

OK I should tell you and I am not sure how long it has been that way or if it was ever even powered up etc etc ... but R456 and c478 which are right next to each other on that board looked like they were in contact. No burn marks anywhere on the legs etc, and I pulled them away. I am not sure if it was something that happened when I was pulling other things, or if it was that way for a long time. But no burn marks for sure, not even any marks that indicated there was a current flow.

Cool.
Srinath.
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Old 30th December 2012, 12:01 AM   #39
srinath is offline srinath  United States
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D458 J2221451534X D-ZENER .5W 5V1 J <- That what the manual says.

Cool.
Srinath.
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Old 30th December 2012, 12:53 AM   #40
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Hi,
That mean that pin 2 should be 5 volts. I looked back the threads but I do not see where you post the voltage at fuse F453. I need that voltage. The voltage to the micro it is pin 4 and it is reading 5.5 volts so the micro it is getting the right voltage it should be 5.5 volts. Now is to find why we have 2.8 volts at pin 2.
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