Philips PM3335/40 scope startup problems
We have a Philips PM3335 combiscope which has begun to get startup
problems, the LCD shows all characters, and CRT is blank (seems like a uController not initialized) When the scope is switched off and in fast sequence switched on again, it most often comes up. I have looked at several signals to the uP (8032AH) especially the RESET line, but I can't see anything obvious. We don't have a service manual for the scope Any tips are welcome. Stein-Olav Lund Trondheim, Norway Service engineer |
Philips PM3335/40 scope startup problems
"Stein-Olav Lund" bravely wrote to "All" (06 Oct 03 12:23:43)
--- on the heady topic of "Philips PM3335/40 scope startup problems" It may be a problem with the LCD display communicating with the uP and nothing wrong with the reset. But the idea may just be a case of killing the messenger. If you strongly suspect the reset line then trace it and replace any dry or leaky electro used for timing you may find. Perhaps a switching diode is associated with the reset cap and diodes sometimes do go intermittant open circuit. Does mechanical force seem to affect the failure to start up? Perhaps a cold solder joint in an area that gets a lot of heat cycling like in the power supply? SL From: Stein-Olav Lund SL We have a Philips PM3335 combiscope which has begun to get startup SL problems, the LCD shows all characters, and CRT is blank (seems like a SL uController not initialized) SL When the scope is switched off and in fast sequence switched on again, SL it most often comes up. I have looked at several signals to the uP SL (8032AH) especially the RESET line, but I can't see anything obvious. SL We don't have a service manual for the scope SL Any tips are welcome. SL Stein-Olav Lund SL Trondheim, Norway SL Service engineer .... High voltage can give a dangerously uncomfortable discharge. |
Philips PM3335/40 scope startup problems
"Stein-Olav Lund" bravely wrote to "All" (06 Oct 03 12:23:43)
--- on the heady topic of "Philips PM3335/40 scope startup problems" It may be a problem with the LCD display communicating with the uP and nothing wrong with the reset. But the idea may just be a case of killing the messenger. If you strongly suspect the reset line then trace it and replace any dry or leaky electro used for timing you may find. Perhaps a switching diode is associated with the reset cap and diodes sometimes do go intermittant open circuit. Does mechanical force seem to affect the failure to start up? Perhaps a cold solder joint in an area that gets a lot of heat cycling like in the power supply? SL From: Stein-Olav Lund SL We have a Philips PM3335 combiscope which has begun to get startup SL problems, the LCD shows all characters, and CRT is blank (seems like a SL uController not initialized) SL When the scope is switched off and in fast sequence switched on again, SL it most often comes up. I have looked at several signals to the uP SL (8032AH) especially the RESET line, but I can't see anything obvious. SL We don't have a service manual for the scope SL Any tips are welcome. SL Stein-Olav Lund SL Trondheim, Norway SL Service engineer .... High voltage can give a dangerously uncomfortable discharge. |
Philips PM3335/40 scope startup problems
Asimov wrote: "Stein-Olav Lund" bravely wrote to "All" (06 Oct 03 12:23:43) --- on the heady topic of "Philips PM3335/40 scope startup problems" It may be a problem with the LCD display communicating with the uP and nothing wrong with the reset. But the idea may just be a case of killing the messenger. If you strongly suspect the reset line then trace it and replace any dry or leaky electro used for timing you may find. Perhaps a switching diode is associated with the reset cap and diodes sometimes do go intermittant open circuit. Does mechanical force seem to affect the failure to start up? Perhaps a cold solder joint in an area that gets a lot of heat cycling like in the power supply? SL From: Stein-Olav Lund SL We have a Philips PM3335 combiscope which has begun to get startup SL problems, the LCD shows all characters, and CRT is blank (seems like a SL uController not initialized) SL When the scope is switched off and in fast sequence switched on again, SL it most often comes up. I have looked at several signals to the uP SL (8032AH) especially the RESET line, but I can't see anything obvious. SL We don't have a service manual for the scope SL Any tips are welcome. SL Stein-Olav Lund SL Trondheim, Norway SL Service engineer ... High voltage can give a dangerously uncomfortable discharge. The problem was burnt RS232 drivers _AND_ the UART in the scope. The 5V was a little low due to this (around4.6V) Stein |
Philips PM3335/40 scope startup problems
Asimov wrote: "Stein-Olav Lund" bravely wrote to "All" (06 Oct 03 12:23:43) --- on the heady topic of "Philips PM3335/40 scope startup problems" It may be a problem with the LCD display communicating with the uP and nothing wrong with the reset. But the idea may just be a case of killing the messenger. If you strongly suspect the reset line then trace it and replace any dry or leaky electro used for timing you may find. Perhaps a switching diode is associated with the reset cap and diodes sometimes do go intermittant open circuit. Does mechanical force seem to affect the failure to start up? Perhaps a cold solder joint in an area that gets a lot of heat cycling like in the power supply? SL From: Stein-Olav Lund SL We have a Philips PM3335 combiscope which has begun to get startup SL problems, the LCD shows all characters, and CRT is blank (seems like a SL uController not initialized) SL When the scope is switched off and in fast sequence switched on again, SL it most often comes up. I have looked at several signals to the uP SL (8032AH) especially the RESET line, but I can't see anything obvious. SL We don't have a service manual for the scope SL Any tips are welcome. SL Stein-Olav Lund SL Trondheim, Norway SL Service engineer ... High voltage can give a dangerously uncomfortable discharge. The problem was burnt RS232 drivers _AND_ the UART in the scope. The 5V was a little low due to this (around4.6V) Stein |
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