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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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Pioneer SP-D4565 convergence, not STKs or caps.
Hi;
Here's a fun one. Side pincushion is way overcorrected. Top/bottom is undercorrected. A few other things are off, but I think this is a major piece of info. I remember corresponding in this NG awhile back about a problem where all the data in the EPROM was reset to +127. The OP didn't give all details on the symptom, but I think it was close. On this set, the STK is working properly, and has been changed. Both red and blue are affected the same way, although with the expected reversals of error. ( another post, on a Toshiba, is the blue convergence pushed harder than the red ? On this one the blue is clipping uslightly/u more) The STKs are only clipping because the drive is telling it to do probably three times the output for which it was designed. My major obstacle here is that it doesn't seem to see the convergence subsystem, it gives me nothing. I got some options for setting default center controls and a few other things, but nothing to do with convergence shows up. In one mode (selected by the mute buttton) I can get the convergence to change from severe over correction, to less severe overcorrection (with some T&B correction starting to come in), and then a much less severe overcorrection which doesn't even cause any on-screen clipping that I can see. The #6 key toggles this. When I hit mute, or anything that exits this mode it reverts to the severe side overcorrection and almost nothing on T&B. The way it is almost seems like three picture modes on a widescreen model. The levels of ALL corrections change, but not enough. While the volume is supposed to change the data (on some), it does nothing, but on a Zenith universal it does do the volume, even in service mode. The original doesn't do anything. There is actually nothing shown on the screen to adjust anyway, it seems not to know it's a projector. On this model the green geometry is analog, with pots. Even though it goes through the STKs, that part of it is working fine. The picture is also washed out, but viewable, but the CRTs seem strong. Nice and sharp. I deem a software problem of this nature has to be addressed first, agree ? My thinking is that this is NOT in the output stage. You would need to increase the values of both Vert conv yoke return resistors and decrease the value of the Horiz conv yoke resistors. Defective STKs would have to have corresponding gain errors. Three outcomes for each device and they all have to come in at once, in that particular way ? I'd play a lotto ticket before checking those resistors, and WTH do they have to do with the missing menu items ? Disagree ? State your case, I'd like to hear the logic of how this could've happened. Of course it could always be power supply, but not to the "PA00XX" chips. They are obviously working. Problem is I got no print. I need something on the architechture of this set. Is there more than one EPROM ? Are the option bits burned into the main micro ? Does the reset routine include a secondary reset for the convergence subsystem ? Does it handshake like an RCA ? If it has a seperate convergence EPROM, where is it ? All indications are that all the cells are set to 0, 255, + or -127 or something like that, but it won't let me set anything. This seems consistent with an initialization problem. I know my posts are long, and I'm sorry, but how many times do we have to tell people to be thorough ? Thanks for your time even reading this, and if you got any answers or even ideas, they would be greatly appreciated. Thanks in advance. JURB |
#2
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Jeff,
Look for a 2SD1276A regulator for the Horizontal Deflection to be leaky. Good Luck on the rest. Bill Jr "JURB6006" wrote in message ... Hi; Here's a fun one. Side pincushion is way overcorrected. Top/bottom is undercorrected. A few other things are off, but I think this is a major piece of info. I remember corresponding in this NG awhile back about a problem where all the data in the EPROM was reset to +127. The OP didn't give all details on the symptom, but I think it was close. On this set, the STK is working properly, and has been changed. Both red and blue are affected the same way, although with the expected reversals of error. ( another post, on a Toshiba, is the blue convergence pushed harder than the red ? On this one the blue is clipping uslightly/u more) The STKs are only clipping because the drive is telling it to do probably three times the output for which it was designed. My major obstacle here is that it doesn't seem to see the convergence subsystem, it gives me nothing. I got some options for setting default center controls and a few other things, but nothing to do with convergence shows up. In one mode (selected by the mute buttton) I can get the convergence to change from severe over correction, to less severe overcorrection (with some T&B correction starting to come in), and then a much less severe overcorrection which doesn't even cause any on-screen clipping that I can see. The #6 key toggles this. When I hit mute, or anything that exits this mode it reverts to the severe side overcorrection and almost nothing on T&B. The way it is almost seems like three picture modes on a widescreen model. The levels of ALL corrections change, but not enough. While the volume is supposed to change the data (on some), it does nothing, but on a Zenith universal it does do the volume, even in service mode. The original doesn't do anything. There is actually nothing shown on the screen to adjust anyway, it seems not to know it's a projector. On this model the green geometry is analog, with pots. Even though it goes through the STKs, that part of it is working fine. The picture is also washed out, but viewable, but the CRTs seem strong. Nice and sharp. I deem a software problem of this nature has to be addressed first, agree ? My thinking is that this is NOT in the output stage. You would need to increase the values of both Vert conv yoke return resistors and decrease the value of the Horiz conv yoke resistors. Defective STKs would have to have corresponding gain errors. Three outcomes for each device and they all have to come in at once, in that particular way ? I'd play a lotto ticket before checking those resistors, and WTH do they have to do with the missing menu items ? Disagree ? State your case, I'd like to hear the logic of how this could've happened. Of course it could always be power supply, but not to the "PA00XX" chips. They are obviously working. Problem is I got no print. I need something on the architechture of this set. Is there more than one EPROM ? Are the option bits burned into the main micro ? Does the reset routine include a secondary reset for the convergence subsystem ? Does it handshake like an RCA ? If it has a seperate convergence EPROM, where is it ? All indications are that all the cells are set to 0, 255, + or -127 or something like that, but it won't let me set anything. This seems consistent with an initialization problem. I know my posts are long, and I'm sorry, but how many times do we have to tell people to be thorough ? Thanks for your time even reading this, and if you got any answers or even ideas, they would be greatly appreciated. Thanks in advance. JURB |
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