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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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#1
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Tektronix TDS220 oscilloscope startup problem
I have a Tektronix TDS220 oscilloscope that has developed this
intermittent startup fault: Sometimes when the power is switched on the LCD will only show a random number of horizontal dark/brihter lines of random widths. The LCD backlight will not be turned on and the mainborad doesn't appear to be working as there will be no 1KHz/5V square wave on the compensation probe output. Also the GPIB interface will not be working. After I reset the mainboard (switch off and on the oscilloscope) several times I eventually manage to get it started and the oscilloscope will work fine for then on, until it is switched off. So I suspect this might be related to a power on reset function (firmware) not being called properly at the startup or maybe some dodgy power supply connection to the main board. I wonder if anyone has had a similar problem and/or could provide some insight about what might be causing this problem. Tektronix UK will charge £425 + VAT (US$775 + tax) to fix it and will take nearly 1 month (apparently they have to be sent to Germany to be repaired). Thanks. Tony |
#2
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Tektronix TDS220 oscilloscope startup problem
I have a Tektronix TDS220 oscilloscope that has developed this
intermittent startup fault: Sometimes when the power is switched on the LCD will only show a random number of horizontal dark/brihter lines of random widths. The LCD backlight will not be turned on and the mainborad doesn't appear to be working as there will be no 1KHz/5V square wave on the compensation probe output. Also the GPIB interface will not be working. After I reset the mainboard (switch off and on the oscilloscope) several times I eventually manage to get it started and the oscilloscope will work fine for then on, until it is switched off. So I suspect this might be related to a power on reset function (firmware) not being called properly at the startup or maybe some dodgy power supply connection to the main board. I wonder if anyone has had a similar problem and/or could provide some insight about what might be causing this problem. Tektronix UK will charge £425 + VAT (US$775 + tax) to fix it and will take nearly 1 month (apparently they have to be sent to Germany to be repaired). Thanks. Tony |
#3
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Quote:
Hi Tony I would think you have an start up power supply failure rather than reset cycle at power up. Have you located power supply values?. Normally they use 15v power supply connected to the battery board. Then multiple power values are generated by switching transformer. I do also have a start-up problem with my TDS3014B, but it start backlight and actually the start screen is Ok. It pulses all front leds for a little bit and then the 1KHz/5V square wave becomes available. Start screen remains without change and there is no any diagnostic message. Troubleshooting chart doesn't cover this situation since it only is useful when diagnostic message apply. It seems to be a software problem rather than electronic problem. Service from Tek is expensive. May you have to try all at your hand to sove yours... I will aprreciate if somebody have an idea to solve this... Regards John_H |
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