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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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KP53XBR45 advanced troubleshooting syscon
You're gonna love this one;
I'm working on this 53XBR45 without a print. I'm not that unfamiliar with this type of unit, so I didn't scream "print, bloody print" when I saw a pretty strange symptom. Every second, or a bit over, for about 1/10th of a second the geometry would change. In the "normal" state, the side pin is off, but this is right for about 100mSec every second. I looked around in there and I find a board with a micro, the jungle IC, and an EPROM on the back. After fiddling around in the menus (at first just the customer ones) I found that changing the color setting might make the set go green, that is shutoff red & blue, not slick green. Other abberations exist when I get into the service menu. None of the values "look" corrupt, changing them frequently has the wrong effect, or no effect, or an effect until the thing cycles again. Changing certain things changes the effect when it cycles, but it always cycles at the same rate. Now I got a micro, jungle and an EPROM on the same board, so I decide to take a shot at the EPROM. Sony EPROMs are not known to be a big problem, at least to me, but I know the higher failure rate of them versus other chips, except for power devices. Reasonable, order the part, especially since it's not expensive. I change it expecting one result, but what I got was the same cycling, but now what it does is flash green. Not slick green, but as if the drive was say tripled during the short part of the cycle. Let me add this, the picture appears as though the picture and sharpness are turned all the way down, but the OSD dosn't confirm this. This was true before as well, it did not change in that respect. The new chip of course isn't set to the set, and now, why bother ? I did save the old one :-) Now I am a bit fuzzy on the data structure and the architchture of this set, but it wasn't built on Mars. After talking to Sony tech ($$) they said a different IC (EPROM) than that which I had changed. I changed IC3002, the EPROM they want me to change is over in the assembly with the tuners and PIP circuit. Now after a bit of thought I wonder if we're BOTH WRONG. Well known fact: these EPROMS and all the chips that run off them are serial data. different data are seperated by timing. These chips are externally clocked. They are clocked by the micro right ? as is everything else ? (not certain parts, especially of the jungle IC) While all the other chips might actually generate data, they don't generate the timing (CLK) right. Only one chip times the system, everything else just reads that. I know that's not true of an RCA DTV series, but it should be true of this set. Although now I may have to regroup, you see, the data are not changing, the abberation is only affecting reads, obviously, so either we have a read that is being obliterated by something else on data & clk. It has to be a chip out of sync. It has to be because it corrects itself, but the it's screwed up again for 9/10th of a second. How come those EPROM values aren't changing, and by now would've changed possibly to values that would not allow the set to run. Here's the kicker: When I changed that EPROM, the set remember it's channels and all settings (or so it thinks), it was still programmed. This leads me to believe the other EPROM is OK. It has to be an IC that can output data, some don't. It has to be something with it's own clock, and THAT is what's out of sync. Of course an EPROM does put out dat . . . . .It could be, I will change it. If anyone ( I am at a loss for words ), thanks in advance. JURB |
#2
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KP53XBR45 advanced troubleshooting syscon
Before you changed the EPROM, did you take a scope and check the drive
pulses in the pin amp to see where the change is coming from. It would be best to get the service manual (available from Sony), and use a scope to go through the related circuits. There are a lot of complicated set-ups in these EPROM's in dealing with the internal set-up of these sets. Not very many shops are even equipped to do the proper factory alignment in these. I would put back the old EPROM (if it still has its original set-up), and properly troubleshoot the set. In all the years that I have been working on Sony sets, I very rarely had an EPROM or uPC problem. Most of the failures in these sets were from caps wearing out, cold solder connections, failed tuner and or IF modules, and or a combination of small parts, and power type semiconductors that have failed. -- Greetings, Jerry Greenberg GLG Technologies GLG ========================================= WebPage http://www.zoom-one.com Electronics http://www.zoom-one.com/electron.htm ========================================= "JURB6006" wrote in message ... You're gonna love this one; I'm working on this 53XBR45 without a print. I'm not that unfamiliar with this type of unit, so I didn't scream "print, bloody print" when I saw a pretty strange symptom. Every second, or a bit over, for about 1/10th of a second the geometry would change. In the "normal" state, the side pin is off, but this is right for about 100mSec every second. I looked around in there and I find a board with a micro, the jungle IC, and an EPROM on the back. After fiddling around in the menus (at first just the customer ones) I found that changing the color setting might make the set go green, that is shutoff red & blue, not slick green. Other abberations exist when I get into the service menu. None of the values "look" corrupt, changing them frequently has the wrong effect, or no effect, or an effect until the thing cycles again. Changing certain things changes the effect when it cycles, but it always cycles at the same rate. Now I got a micro, jungle and an EPROM on the same board, so I decide to take a shot at the EPROM. Sony EPROMs are not known to be a big problem, at least to me, but I know the higher failure rate of them versus other chips, except for power devices. Reasonable, order the part, especially since it's not expensive. I change it expecting one result, but what I got was the same cycling, but now what it does is flash green. Not slick green, but as if the drive was say tripled during the short part of the cycle. Let me add this, the picture appears as though the picture and sharpness are turned all the way down, but the OSD dosn't confirm this. This was true before as well, it did not change in that respect. The new chip of course isn't set to the set, and now, why bother ? I did save the old one :-) Now I am a bit fuzzy on the data structure and the architchture of this set, but it wasn't built on Mars. After talking to Sony tech ($$) they said a different IC (EPROM) than that which I had changed. I changed IC3002, the EPROM they want me to change is over in the assembly with the tuners and PIP circuit. Now after a bit of thought I wonder if we're BOTH WRONG. Well known fact: these EPROMS and all the chips that run off them are serial data. different data are seperated by timing. These chips are externally clocked. They are clocked by the micro right ? as is everything else ? (not certain parts, especially of the jungle IC) While all the other chips might actually generate data, they don't generate the timing (CLK) right. Only one chip times the system, everything else just reads that. I know that's not true of an RCA DTV series, but it should be true of this set. Although now I may have to regroup, you see, the data are not changing, the abberation is only affecting reads, obviously, so either we have a read that is being obliterated by something else on data & clk. It has to be a chip out of sync. It has to be because it corrects itself, but the it's screwed up again for 9/10th of a second. How come those EPROM values aren't changing, and by now would've changed possibly to values that would not allow the set to run. Here's the kicker: When I changed that EPROM, the set remember it's channels and all settings (or so it thinks), it was still programmed. This leads me to believe the other EPROM is OK. It has to be an IC that can output data, some don't. It has to be something with it's own clock, and THAT is what's out of sync. Of course an EPROM does put out dat . . . . .It could be, I will change it. If anyone ( I am at a loss for words ), thanks in advance. JURB |
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