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

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.

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

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

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

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

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

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

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

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

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 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

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

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

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

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

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

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

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, 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