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2465 - impending U800 failure?

 

--- In TekScopes@..., "iofish" <iofish@...> wrote:

Chris

Beam Find will center and shrink the display. The display may look fairly well centered with the U800 failure. What you describe souns like a U800 failure, however at least check your power supplies first. Also make sure one of your horizontal CRT wires are not loose.
Good luck,
Dan

--- In TekScopes@..., "cmjones012003" <chris@> wrote:

Hello all,

I haven't posted to this list in a long time but have just been lurking, I'm afraid.

One of my trusty 2465s has started to give trouble. It's serial number 102481. I bought it used, surplus about 10 years ago and it's had plenty of hard use since, being my daily workshop scope. I've never even undone the case screws - it's Just Worked, and stayed spot-on accurate. I think the tube is a bit tired, since the trace loses focus at high brightness and it's impossible to get the whole screen (corners and centre) exactly in focus at the same time, though it's always been like that and it's good enough.

Yesterday, I switched it on to use it, and it came up as usual but after a couple of minutes the entire display, readouts and all, suddenly jumped off the right hand side of the screen and stayed there. I could just about see the left hand end of the trace by winding the horizontal position all the way over to the left, and the scope was clearly still working otherwise: the bit of trace I could see responded to input signals and adjustments of the controls. I noticed also that pressing the 'beam find' button put the display back in the centre, but shrunken as I'd expect.

I tried the scope again a little later on and the display came back, but tried it again today and it worked for a few minutes then suddenly jumped off to the right again.

I do have the service manual for it, but before I start digging in, are these the typical symptoms of U800 failure? Searching the group, it seems that U800 failure tends to push the display to the left, and I haven't seen anyone document how 'beam find' behaves in that case.

Thank you in advance
Chris
Cambridge, UK

--

Does a mechanical shock (good old tapping at the side of
the instrument) make any difference and brings display back?
If yes, i'd rule-out U800 failure.
 

If Chris' unit is a true 2465 (not a 2465A or B) it has no battery.
The 2465 uses an EEPROM for storage.

--Victor

--- In TekScopes@..., Dan Rae <danrae@...> wrote:

On 1/17/2013 1:16 AM, cmjones012003 wrote:
I tried the scope again a little later on and the display came back, but tried it again today and it worked for a few minutes then suddenly jumped off to the right again.

I do have the service manual for it, but before I start digging in, are these the typical symptoms of U800 failure?
Chris, I don't know how typical, but this is exactly what mine did
having I bought it "working" at our local swap meet. I would not say
impending, I think it has happened. Eventually I replaced the U800 with
one found in a "parts unit" bought on eBay for $125 and all has been
fine since. Obviously this required a bit of risk taking. Sources for
the horizontal hybrid are few and far between, and I didn't like the
alternatives. My "parts unit" has provided a few other things that have
come in handy, a spare tube, fan and HV module among others.

In the end, I did a complete overhaul, loads of new caps, new battery,
and a full calibration, so I'm hoping it will see me out.

Yours at least will probably also need a new memory battery if you've
had it that long.

Dan
 

You are correct about the battery of course Victor, I had been working on a 2465A at the same time and it was a year ago then. But my main point about the U800 is correct, that is exactly how the fault showed.

On 6/25/2013 11:18 PM, victor_j_silva wrote:
If Chris' unit is a true 2465 (not a 2465A or B) it has no battery.
The 2465 uses an EEPROM for storage.

--Victor

--- In TekScopes@..., Dan Rae <danrae@...> wrote:
On 1/17/2013 1:16 AM, cmjones012003 wrote:
I tried the scope again a little later on and the display came back, but tried it again today and it worked for a few minutes then suddenly jumped off to the right again.

I do have the service manual for it, but before I start digging in, are these the typical symptoms of U800 failure?
Chris, I don't know how typical, but this is exactly what mine did
having I bought it "working" at our local swap meet. I would not say
impending, I think it has happened. Eventually I replaced the U800 with
one found in a "parts unit" bought on eBay for $125 and all has been
fine since. Obviously this required a bit of risk taking. Sources for
the horizontal hybrid are few and far between, and I didn't like the
alternatives. My "parts unit" has provided a few other things that have
come in handy, a spare tube, fan and HV module among others.

In the end, I did a complete overhaul, loads of new caps, new battery,
and a full calibration, so I'm hoping it will see me out.

Yours at least will probably also need a new memory battery if you've
had it that long.

Dan

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