Hi Rich, This is useful. Your drawing shows pin 42 (GND/CAL) going to relay coils. Pin 46 (SIG_EN) should go to the coil and pin42 should be going to one of the relay contacts. K2 relay enables calibr

Hi Rich, Looks like magic smoke escaped out of that amplifier. Most likely input pair is damaged and there is a short between input and bias network (likely a tail current source). Ozan

TDS380 attenuator is on page 256 of SM but it doesn’t show the expected attenuator output voltage. Page 238 for 340A/360 has a note "0V common mode, 6.25mV/div/side" to show the expected output. It is

I see from the pictures the hybrids are soldered. I agree, it is very difficult to solder/desolder those substrates. On TDS7104 they are connected by compression. Still replacing relays was very trick

Hi Richard, I don't have a TDS380 but I have debug experience on TDS520, TDS520A, and TDS7104. Looking at schematics briefly TDS380 looks similar. Do you see a voltage of opposite polarity (i.e. -0.25

Great news, congratulations for the fix. Ozan

I agree this needs to be investigated further. Easy explanation is N4 signal on <11> is wrong but we looked at it before. --- copied from our earlier exchange -- -- end copy --------------------------

Hi Torquil, ------ I don't have a 465B but B sweep delay circuit works similarly on several scopes. On sheet <7> Q7067 compares delay potentiometer voltage to "A ramp" voltage. Depending on where ramp

Hi Ondrej, Great news that relays fixed many of the issues, congratulations. As you know in 521 setting only B sweep is used so if you look at "B sweep from Q1236" on sheet <11> it should look the sam

Hi Stephen, Did you look at the SMs at : https://bama.edebris.com/manuals/tek/465(2)/ and https://bama.edebris.com/manuals/tek/465/ Ozan

It is interesting to note that MOSTEK NVRAM has "PRE-QUAL" marking. Unless it means something else during that time, this looks like pre-production unit. It is common to give engineering samples to cu

You may already know but at least in some service manuals component placement diagram shows location of C1132 and C1115 swapped (wrong). This was the case for my 2467B, I assume it also applies to 246

I agree sometimes stepping back and looking with fresh eyes helps. Let us know when you want to bounce off ideas again. Ozan

In this video I think I know what is happening. You have variable horizontal knob out (time 0:13 in the video). Your 5ns B gate is 300ns wide instead of ~ 130ns Raymond measured so this is supporting

What is the B sweep voltage level when there is no sweep? Both A and B sweep are expected to reset to +13V and should go down from that level when gate starts. When you say it doubles does it always s

It is better to place the proper value, 820-ohm nominal, in both places. Voltages look OK ballpark. Perhaps some of the transistor gains decreased over time and now positive feedback coming back throu

Can't think of an easy explanation. When you are making the table could you also mark down both A gate width and B gate width while you are measuring B sweep timing? Also please observe if you really

The relay doesn't change state until you hit 200ns. It could still be bad but I don't see how it could create the behavior you are seeing. The good news is it is on a socket, you can easily pull it of

Take a look at the posted pictures: https://groups.io/g/TekScopes/album?id=262059 Latest 5 pictures for B sweep in 1ns/div to 20ns/div. As expected no change in B-gate from 1ns/div to 2ns/div, then B

As far as I remember B-gate time stays the same from 1ns to 2ns (because of the reason I mentioned before) then increases at 5ns. I will look at what happens on my scope but I expect it should continu