I have seen a rare lot in

Mark, Yes, I believe the intent is to "highlight" part of the trace; however, mine is highlighting much to bright. I'll have to check those voltage levels in the Z-Axis circuit and see if the

Stephen, I'll have to check that. I think the problem is seen for other time-bases so not sure if it's a problem with the plugin but it could be. Thanks, Barry - N4BUQ

Hi Walter, --- 485 has an active protection circuit that flips input relay to 1M-ohm setting to protect the 50-ohm attenuator. There could be a fusible element as well although I can't see it in the

The next step seems to be to power the board to investigate further. The HV section is basically this (but my unit shows some updates as mentioned previously): https://imgur.com/gtO35ue Can anyone

Jeff, 50 ohm protection on the 485 is a fusible ceramic element in the attenuator chain, a rare and hard to find object. having said that, the 485 scope is very nice, but quite complex (especially in

Barry, Maybe the discussion of Aux Z axis Control and Aux Z Axis Out on pages 3-16 and 3-17 of the 7B53A manual will give a clue. It describes the Z-Axis interface to the mainframe. Since the 7B92A

My brother-in-law worked for a law firm that specialized in maritime law.  He tells a story that happened at the port of Oakland- someone was importing two old MIGs, and they had survived the trip

I have driven forklifts and worked in a workbasket from one. That time, the idiot driver who was assigned to the job kept disappearing. It ran out of propane while I was working near the roof, running

For those that have a 485, look at the S/N to see if it is in the lower range. At one point it was changed to protect the round IC from pluses from the relay coil when switching from 50 ohm to 1meg

Barry, See if having the A/B intensity turned up and the crt bias up (more negative at the grid) helps. If your S/N is <210000, check Q320, Q322, Q420 and Q422. These are in the two heatsinks on the

No disrespect taken :) Looking at the circuit diagrams, the 485 has two separate attenuators, one 1Mohm and one 50ohm. A relay connects the BNC input to the relevant attenuator. Overload causes the

Mark, Intensity settings for normal traces are about right. The main intensity is somewhere near mid-range and the A/B intensity controls are in the 9:00 to 12:00 range (or less). I'm using a 7B53A

Barry, It sounds like the time base you are using is the source of the delayed sweep. Some have an intensity control for the delayed sweep. A 7B92A is an example. The 7704A has two main intensity

The delayed sweep intensity is way too bright in my 7704A. If I understand it correctly, a time-base sends a signal to the mainframe to indicate the delayed sweep is active and the mainframe knows to

Jean-Paul, I have already lucked out on a 2465 in January of this year, which cost slightly less than this 485 ($120 before shipping). I'm not really interested in the 2465A or 2465B, both because

Tom, no disrespect intended, but I'm looking directly at my 2465, and it has five input coupling positions for channels 1 and 2, labeled in order: 1MΩ AC, 1MΩ Gnd, 1MΩ DC, 1MΩ Gnd, and 50Ω DC

Dear Jeff the trigger difference is the least of the considerations Beware the 485 are very old, notice the small gray knobs are deteriorated. The ebay lot has total with shipping $225 minimum, and

On 485, A Ext trig view is the little button at left end of vert mode switches.

The 485 has two separate inputs: 50ohm and 1Mohm//20pF. The 24x5 have 1Mohm//15pF inputs, and you can add a 50ohm resistor to make that 50ohm//15pF. By and large, my preference is for two "proper"