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So I’m getting no horizontal sweep and I can only move the spot a bit left but full right as seen in video.
Where do I start now?

I assume you've checked that all the power supply voltages are within spec.
Is the sweep generator working at all? I suspect it's either locked up and/or has a severe offset.
Or maybe something downstream of it has failed, causing the voltage on the deflection plates to be unequal unless the H-Pos is near its extreme.
A lot of things come together in the horizontal circuit, triggering, hold-off, blanking,
I have a 465M so I don't know if there's a difference in the circuitry but in the packaging there sure is.

Have you verified that the horizontal deflection wires are connected to the CRT?

Have you done a visual inspection of the sweep and trigger boards?

Have checked the power supply voltages?

Any of these are good places to start.

-- Jeff Dutky

Check Q344, Q678 and Q688 between C and E. If leaky, use KSP10BU (BEC pinout). Check voltages in the horizontal circuit to see if any are off. See where you loose the signal from the time/div. switch. Clean the sockets where the transistors are and any switches you have not cleaned yet.

Mark

Moving to both sides of the screen in a Tek oscilloscope needs both deflection plates active with the correct signals.

1) check to see that both horizontal plates are connected.

2) check to see that the signals from the plates back in the horizontal amplifier are symmetric.

3) since the horizontal amplifier is has a single ended to push-pull input stage (in most cases) and you get a sweep, then the sweep and horizontal input amplifier are likely fine.

4) alternatively, after checking the plates, you can put in the required signal to the horizontal amplifier and go through checking voltages and waveforms.? The top section (driving one plate) and the bottom section should pretty much have the same voltages, but a mirrored (180 degrees out of phase) signal.

5) doesn't matter (after you check the wiring to the plates) whether or not you start at the beginning of the amplifier or the end.

6) it's a DC amplifier, so the voltages are important and there are no coupling capacitors to fail.

Harvey

Harvey,

Is he getting a sweep? The video does not show a working sweep.

The complete lack of sweep looks a lot like the failure I saw on my dad's 475, but the timing board on the 465 is a very different layout (e.g. I don't see any of the big axial caps that are so in-your-face on the 475 sweep board). The failed component for me was a smaller silver axial electrolytic cap (C1059), that looked a lot like the timing caps, but turned out to be just a decoupling cap on the +110V rail.

I still don't understand how the failure of that decoupling cap brought down the whole sweep circuit. It wasn't shorted to ground, so it probably wasn't pulling the +110V rail down, but it brought the whole sweep to a dead stop. All I had was the spot sitting in the center of the screen, no matter what I did with the TIME/DIV switch (I don't think I tried putting it in X-Y mode: it might have responded correctly to that).

So that suggests something else that could be tried in this case: put the scope in X-Y mode and see if you can move the spot horizontally by applying a signal on CH 1.

-- Jeff Dutky

Ok I’m going to give more details as I left a few out. When I received this it had no power and it turned out to be the infamous tantalum cap in the HV section, replaced with electrolytic. I then had power and just a dot with no vertical or horizontal sweep just a dot. I changed out the filter caps to put and ripple issues behind and all other electrolytic with the exception of the matched ones. I cleaned all switches and connectors the best I could, very time consuming, I used MG Alcohol so no residue would be left behind. I then got the vertical sweep back and part of the horizontal as that is where I am now.
I took another video showing a bit of weirdness:



My next step is going to check the Horizontal Deflection Plate leads and see if I’m getting a signal as suggested by Harvey.

Andrew

Oh I forgot to include that all my test point voltages are spot on.

Interesting that the screen un-blanks and lights up when you set the sweep speed to X-Y. This mode causes the Z-Azis logic to unblank. See if you can find out why it's (almost) always blanked. I suspect you've got an undiscovered shorted tantalum gumdrop.

The 465 series scopes use tantalum capacitors. They are known to short out and bring the scope down.
Typical symptoms will be no trace, or powering on and going off in a few seconds due to built-in fold-back protection. The shorted capacitor in the power rails will bring down one (or more) of them causing the entire scope to be non-functional. The quick way to troubleshoot is, after powering off - and ensuring all capacitors are discharged - check resistance to ground on each power supply rail and identify the shorted power rail. Then trace the offending tantalum capacitor in the shorted rail with the help of a schematic. This could be in any board/sub-assembly, not necessary in the power supply or A9 board. You can replace tantalum caps with general electrolytic. Remember to ensure you install them in the correct polarity, specially on the negative rails.

Have a look at this thread:
/g/TekScopes/message/161306?p=%2C%2C%2C20%2C0%2C0%2C0%3A%3ACreated%2C%2C465+No+Horizontal+Sweep%2C20%2C2%2C0%2C40966357

So what's going on when you get the scope into X-Y mode? The screen lights up like a storage scope with the intensity up too high (the whole screen glows an even bright green). What we expect in X-Y mode is to see sharp dot in the center of the screen (or a line, if you are feeding a signal into one of the inputs, as you are). Instead we get this weird even illumination of the CRT.

You do seem to be getting horizontal sweep on some low ranges, which is a good sign. It might mean that you've just got bad switch contacts in some positions, or it could mean that some of the timing caps are dead (or maybe that some other components around the timing caps are dead?). The leaf contacts on these scopes are a known maintenance hassle, and you said that you cleaned them in the recommended fashion. You should be able to verify that the leaf contacts are closing correctly with a simple multimeter continuity test (simple, but time consuming, because there are a bunch of contacts to check).

It might also be the case that the cam drum is not rotating and has broken internally. This is also a known issue with these scopes. It's a bit more work to address than the dirty leaf contacts, but entirely doable. Several people on the group have done this recently, and there was even an active conversation about the process in the past week or two.

I think that you are making some progress on this, though it may not feel like it.

-- Jeff Dutky

Well after checking every tantalum cap for a short I decided to poke the Low Voltage TP’s.
Checking for shorts to ground from TP’s -8vdc, 5vdc and 15vdc I see resistance but no short. Then I test the 55vdc and 110vdc I show an open “OL” no resistance.

Andrew

On Sat, Dec 25, 2021 at 09:37 PM, KB2LMN wrote:

Then I test the 55vdc and 110vdc I show an open “OL” no resistance.

Definitely should not be reading open. There might have been some charge in the caps that fooled your meter. They should read as a low resistance that increases.

The recommended. but rarely followed, application of tantalum caps calls for about 3 ohms per volt. So caps connected to the 15V supply will be through a 47 Ohm resistor, like R1038. These can hide a shorted cap. I found several in my SC502 that acted as fuses, and some that just sat there and cooked.

You could do a quick test of the horizontal amplifiers by feeding a sine, ramp, or triangle signal into the X input in XY mode and see if you can get a horizontal line or 2 dots with a square wave. Then I'd go looking for the reason that the display always seems blanked except in XY mode.

A bad switch contact is also a definite possibility as Jeff pointed out. And those cam switches may seem intimidating, they are actually rather simple but require a lot of patience.

Dave - AC2GL

It must be tricking my meter I’m going to test again as I’m seeing the correct voltages?

On Fri, Dec 24, 2021 at 08:43 AM, KB2LMN wrote:

Oh I forgot to include that all my test point voltages are spot on.

OK, if your test point voltages and ripple are "spot on", why are you measuring resistance to ground at the test points? This test is only useful when one or more supplies is out of specification or near Zero volts. If ALL of your LV test point voltages are as you indicate, then you do not have a short, otherwise one or more rail would be "loaded down". We know that the HV is working, since you have a spot. Now you need to follow those voltages through to the other boards to make sure that there is not an open circuit in one of the supply rails to the various boards. Time to begin diagnosis of the sweep generator and other elements of the horizontal system.

--
Michael Lynch
Dardanelle, AR

I placed a pic in the photos 465 issues album of my resistance and voltage reading. I used a fluke 8842A and got much better readings.

Hope everyone had a great Christmas and New Year! Just an update where I am, I haven’t given up I ordered a manual with fold out schematics as I’m having a very hard time viewing it online. I’m more of a book guy than screen guy.

Andrew

You might look at this for some troubshooting ideas:

On Fri, Dec 24, 2021 at 06:14 AM, KB2LMN wrote:

I took another video showing a bit of weirdness:

----
It looks like sweep runs to the end but doesn't get reset to initial condition (to all the way to left, slightly off screen). What you are seeing is end point of the sweep, which should be slightly off the screen and visible if you move horizontal position to left as you did in the video.

In one case you were able to get the sweep wait at left, probably it was in NORM and no trigger came. Beam finder showed it as expected. In another case you were able to get one sweep, it ran but stayed at rightmost position without resetting to left.

Sweep waiting at rightmost point is not a valid state and I recommend debugging it first since it is a static invalid state. In sheet <6> what voltage do you see at the collector of Q1036? If it is ~ 0V and stays there Q1012/Q1024 may not be sending the sweep end signal. If you summarize the voltages, while screen shows the dot(s), at:
Collector of Q1036
Base and emitter of Q1002B
Base, emitter, collector of Q1012 and Q1014
there may be some clues.

If they are fine next step would be to look at voltages at pins of U870 to tell the state of sweep.

Ozan

Andrew,
I noticed in your video that you were changing trigger selections of the B Trigger. Perhaps you have already figured this out, but if you haven’t, the A Trigger controls are below the Time/Div knob. Mess with those a bit. You should find some sensible settings such as Auto mode to get a repeating sweep. You might also select XY on the Time/Div apply sinusoidal signals to both CH1 and CH2. You will need fiddle with Volts/Div and associated position controls.
It might reveal something useful.

OK I took the following voltage readings as suggested by Ozan

Q1036 Collector 0.114
Q1002B Emitter 13.46 Base 12.71
Emitter 13.68 Base 0.114 I wasn't sure what side was A or B, looking at the board it is on the bottom right, looking at the transistor the top set of voltages is the left and bottom the right
Q1012 Base 2.58 Emitter 0.137 Collector 0.192
Q1014 Base -0.545 Emitter 0.131 Collector -2.633