Just as a final note on this thread, I ran through the performance checks in the service manual and apart from a couple of minor adjustments all the features worked as expected and calibration was spo

I wouldn't worry too much about all the Tantalum caps in the scope. There are rather a lot of them. You are unlikely to see them burned up. They just short internally. There are a handful in the power

I would start by checking all of the power supply rails including +5V, +15V (reg and ureg), +50V, +110V and +105V/+160 unreg, as well as -8V and -15V. Sometimes the Tantalum caps fail with a short. Oc

This issue has now been addressed. Thanks to all who provided comments. Details here: https://groups.io/g/TekScopes/message/172426

That's an interesting observation. Some time ago I came across a 465 that had an intermittent shorting -8V supply due to a faulty smoothing can but so far in the 468 all supplies are good and as it tu

I finally found it! :-) After checking that -8V and +15V were present around the trigger offset inputs and voltages around the diodes were as indicated, and so ruling out this part of the circuit, I t

Thank you for that explanation. Much appreciated. Will check these out as well although I can confirm the presence of -8V at the input to R689, but also at the junction of CR679 and R679. There is als

According to the Service manual, page 5-38 (volume 1 if you have the version split across volume 1 and volume 2) the service ROM is fitted in place of U565. It has been 4 days and I seem to be no clos

I have a problem with X-Y mode not working on my 468 scope. The spot it hard left and beamfinder is required to show it. Other running traces are absolutely fine. I had another discussion open for the

Michael, thanks for posting that Tek cross-reference. I was looking to determine what part number 156-0048-03 is in my 468 is and found it in there. I knew it was a transistor array of some kind but t

Just a bit of an update on the X-Y mode troubleshooting so far. While a trace is running there is a sweep angle on both plates as might be expected. In X-Y mode there is 100VDC on one plate, zero volt

I have a question about the options that this scope has and X-Y mode. On the back it lists: Opt 4 Mod (stamped on chassis between the two option labels) Opt A2 What is option A2? I can't find a refere

With further investigation I have concluded that TIME cursors look like they are measuring pretty spot on. With a 1kHz signal it, in fact, measures 1.056mS which is correct. At 10MHz the measurement w

The crystal has been replaced and the clock seems stable after a 1hr soak so this is looking good. I ran through the storage functions today and the good news is that all storage functions are operati

Thank you. Learned something today then! According to one source the scope was produced from 1980 to 1985, so that would indicate that this unit is a fairly early example. The serial number is in the

An interesting point about the manual. The serial number of this unit starts B0xxxx which, according to the manual means it was manufactured at Tektronix, Inc, Beaverton, Oregon, USA. The manual does

I have traced the problem with the display to one of the driver chips, an 74LS374. A replacement is on its way. It seems an 74LS377 had been used and there are a number of these on the board as well a

I made a more details assessment of the scope this morning. First, I gave the ICs on the ADC/memory board a wiggle just to make sure they were all properly seated and the pins were making contact. Aft

Bit more progress today!. The replacement CPU arrived and has been installed. I am now getting all of the correct signals on the CPU board as per the service manual and comparable with Tony's "quick o

Thank you for uploading this.