2467B with display anomalies


johnasolecki@...
 

My 2467B has developed several problems with the display; I'm not sure if they're related or not but they started about the same time.

The first is if I put a sine wave on the screen and center it, it shows considerable distortion. If I move it well above or just below the center line it displays clean.
Secondly, as soon as a signal is applied the upper and lower readout will oscillate like a sine wave is passing through them. Still readable but definitely not proper.

It's my favorite scope; I'd be grateful for any suggestions on where to start looking.

John


Roger Evans
 

If Ch3 and Ch4 display the sine wave OK at all vertical positions but Ch1 and Ch2 have similar distortions it could point to a problem with the vertical channel switch hybrid.

There are many others here with wider knowledge than me so you will probably have other suggestions.

It is possible to carefully clean the contacts on the hybrid, replacements tend to be expensive.

Regards,

Roger


Siggi
 

Hey John,

First port of call would be to check all the power supply voltages &
ripple. You have a service manual I trust? There's a section in the service
manual detailing the measurements. The power supplies are all brought out
to J119, which is on the mainboard of the scope.

While you have the scope open, if your A5 board is the SMD version, you'll
want to check the electrolytics on the board for leakage. Even though the
display trouble you describe wouldn't result from that, you don't want to
wait until they leak.

Siggi

On Wed, Mar 3, 2021 at 11:29 AM <johnasolecki@gmail.com> wrote:

My 2467B has developed several problems with the display; I'm not sure if
they're related or not but they started about the same time.

The first is if I put a sine wave on the screen and center it, it shows
considerable distortion. If I move it well above or just below the center
line it displays clean.
Secondly, as soon as a signal is applied the upper and lower readout will
oscillate like a sine wave is passing through them. Still readable but
definitely not proper.

It's my favorite scope; I'd be grateful for any suggestions on where to
start looking.

John






Jean-Paul
 

Hello I had the exact oppsite symptom: CH1, 2 30% nonlineariyt as traces enter lower 1/3 of CRT, but fine in center or top.

CH3, 4 OK.

I used a triangle wave to see the nonlinearity clearly.

Chuck mentioned that this symptom is indicating a failed Hybrid, Channel switch U400.

You can find the signals in and out of the TEK Hybrid on the A1 main bd schematic.

IF it is indeed U400, BEWARE: Used parts on epay or from China may also be defective, TEK 155-0236-00

Q service in Greece has them ~$100, or perhaps Sphere in BC.

Be careful in replacing, static sensitive and follow Chuck's procedures to remove and reattached.

Bon Chance,

Jon


johnasolecki@...
 

I had checked Channels 3 & 4 previously and forgot to add that they work properly. Looking more like U400.