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| Tektronix Arbitrary Function Generators (and Rigol too) |
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| Mark_O:
The 2303 code is a Chan 1 Output offset failure. And the 1103 code is saying there was a Chan 1 Output offset Cal failure. I.e., it can't Calibrate successfully, because it can't adjust that output offset. Due to the resistor. Pretty logical connection. On the fried resistor, I'm sorry I'm unable to help with that. The Tek Service Manual for that instrument does not provide that level of Parts identification. They only discuss Replaceable Parts, which is at the board level. You will need to find an owner of this generator, and hope they will open theirs and take a look inside. All I can see from your Pic is R90 on the PCB, and that may be only part of the ID. I.e., could be R901, or whatever. Or possibly, since that is a 2-channel generator, look for the corresponding resistor for Chan 2. Which was NOT blown. You should be able to trace that out on the PCB. And grab the value off that (or measure it, if it is unlabeled). |
| lern01:
--- Quote from: Mark_O on November 23, 2023, 08:51:30 am ---The 2303 code is a Chan 1 Output offset failure. And the 1103 code is saying there was a Chan 1 Output offset Cal failure. I.e., it can't Calibrate successfully, because it can't adjust that output offset. Due to the resistor. Pretty logical connection. On the fried resistor, I'm sorry I'm unable to help with that. The Tek Service Manual for that instrument does not provide that level of Parts identification. They only discuss Replaceable Parts, which is at the board level. You will need to find an owner of this generator, and hope they will open theirs and take a look inside. All I can see from your Pic is R90 on the PCB, and that may be only part of the ID. I.e., could be R901, or whatever. Or possibly, since that is a 2-channel generator, look for the corresponding resistor for Chan 2. Which was NOT blown. You should be able to trace that out on the PCB. And grab the value off that (or measure it, if it is unlabeled). --- End quote --- Can you provide specific repair suggestions? The output offset should be caused by incorrect DC bias, right? Mainly in which part? The large resistor is the ground resistor of the 5V regulated power supply. It should have a very small resistance, so I short-circuited it directly. It should have no effect on the generator motherboard. I measured several voltages from the CPU motherboard to the generator. When working, +18V -18V 4.2V +5V are basically normal, but -5V is only 4.88V. Is it related to this? no load-4.91V. |
| Mark_O:
--- Quote from: lern01 on December 03, 2023, 05:01:28 am ---Can you provide specific repair suggestions? The output offset should be caused by incorrect DC bias, right? Mainly in which part? --- End quote --- Yes. In the resistor that was blown. :) I made a mistake when reviewing the Service Manual, which describes the 2-channel version of this ArbGen. Then I noticed yours is labeled a a 1-channel unit. However, often these are designed as dual-channel, and then just have 1-channel left unpopulated. As you confirmed with the blank section of the PCB, with the BGA pads. So if you found the matching resistor for Chan 2, it could also be unpopulated as well. :( I think your best bet on fixing this is to start with the blown resistor, and replace that. (though one might ask what would cause that part to melt down.) Using the KISS principle, find someone who has a working unit, and find the value. I don't have one myself, so I can't help you there. But you might track down an email contact to someone at Tek, who could check and give you that resistor value. I'm guessing they still have the info in their database, even though this instrument was discontinued long ago. But they may be reluctant to take the time to track it down. Time is money, everyone is busy, and no money will be made by getting this unit functional again. |
| lern01:
--- Quote from: Mark_O on December 03, 2023, 01:53:51 pm --- --- Quote from: lern01 on December 03, 2023, 05:01:28 am ---Can you provide specific repair suggestions? The output offset should be caused by incorrect DC bias, right? Mainly in which part? --- End quote --- Yes. In the resistor that was blown. :) I made a mistake when reviewing the Service Manual, which describes the 2-channel version of this ArbGen. Then I noticed yours is labeled a a 1-channel unit. However, often these are designed as dual-channel, and then just have 1-channel left unpopulated. As you confirmed with the blank section of the PCB, with the BGA pads. So if you found the matching resistor for Chan 2, it could also be unpopulated as well. :( I think your best bet on fixing this is to start with the blown resistor, and replace that. (though one might ask what would cause that part to melt down.) Using the KISS principle, find someone who has a working unit, and find the value. I don't have one myself, so I can't help you there. But you might track down an email contact to someone at Tek, who could check and give you that resistor value. I'm guessing they still have the info in their database, even though this instrument was discontinued long ago. But they may be reluctant to take the time to track it down. Time is money, everyone is busy, and no money will be made by getting this unit functional again. --- End quote --- yes,I don't believe they will help with this either. there is no way they would spend time looking for information on equipment that has been discontinued for many years. |
| lern01:
Fortunately, I got help from my friends at w2aew and learned that it was a MOV, model number TNR5C820K, oxide varistor. Just as I originally suspected, this fault has nothing to do with the resistor. |
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