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Tek 455 Vertical deflection question
High ripple doesn't require component failure, just too much current being drawn from the supply. I am using the phone at the moment so it is not easy to find the location of the suspect cap but it so
High ripple doesn't require component failure, just too much current being drawn from the supply. I am using the phone at the moment so it is not easy to find the location of the suspect cap but it so
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By
Roger Evans
· #193453
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Tek 455 Vertical deflection question
James, I find this very puzzling! From your measurements on the vertical deflection plates it should be possible to set the vertical position control so that the voltages on the two plates are equal.
James, I find this very puzzling! From your measurements on the vertical deflection plates it should be possible to set the vertical position control so that the voltages on the two plates are equal.
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By
Roger Evans
· #193441
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Tek 455 Vertical deflection question
After checking the connections: 1. Measure the voltage on each deflection plate for the two extreme settings of the vertical position control. 2. Check that Ch1 and Ch2 have exactly the same behaviour
After checking the connections: 1. Measure the voltage on each deflection plate for the two extreme settings of the vertical position control. 2. Check that Ch1 and Ch2 have exactly the same behaviour
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By
Roger Evans
· #193429
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2445A CH1 attenuator
Siggi, Thanks for the extra information, it saves me stripping down my 2440 attenuator. The relays are not reed relays, which are almost always sealed as Fred says, but are latching relays with two en
Siggi, Thanks for the extra information, it saves me stripping down my 2440 attenuator. The relays are not reed relays, which are almost always sealed as Fred says, but are latching relays with two en
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By
Roger Evans
· #193358
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2445A CH1 attenuator
Looking at the construction of my spare attenuator module (removed from a 2440 part 119-2342-10), you should be able to remove the black plastic cover that holds the four latching relays, carefully re
Looking at the construction of my spare attenuator module (removed from a 2440 part 119-2342-10), you should be able to remove the black plastic cover that holds the four latching relays, carefully re
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By
Roger Evans
· #193334
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What's the value of a C-12 camera: both the idea of what it can be used for, and is it worth anything more than being a door stop?
The lenses were serious pieces of optics in their day, relatively fast f-numbers, flat field and almost zero geometric distortion. Unfortunately they only meet these demanding requirements for the des
The lenses were serious pieces of optics in their day, relatively fast f-numbers, flat field and almost zero geometric distortion. Unfortunately they only meet these demanding requirements for the des
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By
Roger Evans
· #193139
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Can't "calibrate" one channel of a 7A26
Tom, I have to admit that I haven't looked closely at the interior of the plugin attenuators, the manual simply shows a 'black box' with a resistor to ground at the mid-point of the box and I simply a
Tom, I have to admit that I haven't looked closely at the interior of the plugin attenuators, the manual simply shows a 'black box' with a resistor to ground at the mid-point of the box and I simply a
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By
Roger Evans
· #193087
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Can't "calibrate" one channel of a 7A26
The 7A26 has small plug-in fixed attenuator modules underneath the aluminium cover that sits immediately behind the BNC connectors. These are T-section resistor/capacitor networks and can give high or
The 7A26 has small plug-in fixed attenuator modules underneath the aluminium cover that sits immediately behind the BNC connectors. These are T-section resistor/capacitor networks and can give high or
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By
Roger Evans
· #193079
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Can't "calibrate" one channel of a 7A26
How do the two channels compare using the built in 1kHz calibrator? Is the discrepancy the same for different positions of the V/div switch and different calibrator voltages? The front panel var contr
How do the two channels compare using the built in 1kHz calibrator? Is the discrepancy the same for different positions of the V/div switch and different calibrator voltages? The front panel var contr
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By
Roger Evans
· #193071
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Revisited: Help required finding a Tek 466 power rail short
Reduced scan mode works by doubling the voltage on the CRT cathode which halves the deflection sensitivity in both X and Y without making any changes to the X and Y amplifiers. If the X scan covers th
Reduced scan mode works by doubling the voltage on the CRT cathode which halves the deflection sensitivity in both X and Y without making any changes to the X and Y amplifiers. If the X scan covers th
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By
Roger Evans
· #192261
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2465 Risetime Check
If my memory is correct Ch3 and Ch4 do not have the 50Ohm option, you need a 50Ohm inline termination to measure their rise time. Roger
If my memory is correct Ch3 and Ch4 do not have the 50Ohm option, you need a 50Ohm inline termination to measure their rise time. Roger
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By
Roger Evans
· #192213
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Help required finding a Tek 466 power rail short
If you want a quick check on which power rail is causing the problem you can completely and individually isolate +15V, +5V and -8V from the rest of the A5 board by lifting one side of the decoupling i
If you want a quick check on which power rail is causing the problem you can completely and individually isolate +15V, +5V and -8V from the rest of the A5 board by lifting one side of the decoupling i
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By
Roger Evans
· #192100
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Help required finding a Tek 466 power rail short
With 8 or 9 hours of time difference a lot has happened since I went to sleep! Last night I had got as far as realising that U1724A was sinking current at its output so was not going to be responsible
With 8 or 9 hours of time difference a lot has happened since I went to sleep! Last night I had got as far as realising that U1724A was sinking current at its output so was not going to be responsible
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By
Roger Evans
· #192037
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Help required finding a Tek 466 power rail short
James, There is a serious anomaly right at the beginning of your voltage tracing. Pin 8 of U1724 should be at +22V, regulated by the Zener VR1725. It looks very much like either VR1725 or U1724 is bad
James, There is a serious anomaly right at the beginning of your voltage tracing. Pin 8 of U1724 should be at +22V, regulated by the Zener VR1725. It looks very much like either VR1725 or U1724 is bad
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By
Roger Evans
· #192000
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2440 for sale
It was very common in the early years of DSOs for the analog signal to be severely under-sampled. I have a late model 2211 which is hybrid analog/digital, has 100MHz analog bandwidth and only 20Msampl
It was very common in the early years of DSOs for the analog signal to be severely under-sampled. I have a late model 2211 which is hybrid analog/digital, has 100MHz analog bandwidth and only 20Msampl
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By
Roger Evans
· #191959
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2440 for sale
The 2440 does 500Msamples/s on each channel simultaneously, so 2nsec between samples. You can use your favourite formula to turn this into a single shot bandwidth, the numbers seem to have changed ove
The 2440 does 500Msamples/s on each channel simultaneously, so 2nsec between samples. You can use your favourite formula to turn this into a single shot bandwidth, the numbers seem to have changed ove
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By
Roger Evans
· #191939
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Help required finding a Tek 466 power rail short
James, Well done for discovering the error but you need to get the +65V fixed before something else gets too hot. You need to (quickly ?) measure the voltage at each point along the chain from (pin 1
James, Well done for discovering the error but you need to get the +65V fixed before something else gets too hot. You need to (quickly ?) measure the voltage at each point along the chain from (pin 1
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By
Roger Evans
· #191738
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Help required finding a Tek 466 power rail short
If pin 2 of U1724A is at close to 9V when the nominal +65V line is at 43V then something is amiss with the divider chain R1735, R1736, R1737, or possibly U1724 is defective. You probably need to lift
If pin 2 of U1724A is at close to 9V when the nominal +65V line is at 43V then something is amiss with the divider chain R1735, R1736, R1737, or possibly U1724 is defective. You probably need to lift
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By
Roger Evans
· #191684
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Continuing saga of the 7904
Morris, Apologies for not interpreting your post correctly. When you say the HV voltage is quite stable I assume you have measured the HV test point at both fast and slow sweep speeds when the demand
Morris, Apologies for not interpreting your post correctly. When you say the HV voltage is quite stable I assume you have measured the HV test point at both fast and slow sweep speeds when the demand
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By
Roger Evans
· #191519
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Continuing saga of the 7904
Morris, This is very much what you expect! If you set the sweep speed to 10nsec/div then the beam is on screen for 100nsec. It then has to wait almost 1msec (1,000,000 nsec) before the next trigger pu
Morris, This is very much what you expect! If you set the sweep speed to 10nsec/div then the beam is on screen for 100nsec. It then has to wait almost 1msec (1,000,000 nsec) before the next trigger pu
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By
Roger Evans
· #191470
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