1. TekScopes@groups.io

Re: Tektronix 454

David Hess
 

I encourage you not to give up on your 454. It has a fabulously
bright and sharp CRT.

I have to ask some of the same questions:

1. Does the trace drift off screen when the input coupling is set to
ground?

2. Does the trace drift off screen when the input coupling is set to
DC and the input is shorted?

One thing that can cause the trace to drift off of the screen is if
the DC circuit path to the grid of V113 shown on schematic 2 is open.
This could include an open R110.

The variable control is R167 and could not cause the trace to drift
off of the CRT by itself.

What does the channel 2 INVERT switch do? It would cause problems if
the switch was bad.

Since only channel 2 is affected, the problem is on either schematic 2
or schematic 3 before the delay line driver.

On Tue, 1 Aug 2017 11:24:52 -0700, you wrote:

Hey I'm very sorry for taking so long to respond. I've been very busy at work and in going out of town soon. I reseated the transistors on the channel 2 vertical preamp. The trace most of the time isn't on the screen so I can't be sure. I haven't seen a trace on channel two in a while. Channel one seems to work fine. Only problem is the red knob on the volts/division doesn't work.

Sent from my iPhone

On Jul 21, 2017, at 8:03 PM, David davidwhess@gmail.com [TekScopes] <TekScopes@yahoogroups.com> wrote:

Which transistors did you reseat?

Does the trace drift off screen when the input coupling is set to
ground?

Does the input response normally while it is on screen?

On Wed, 19 Jul 2017 22:06:56 -0700, you wrote:


Hey everyone my tektronix 454 channel two doesn't work. It worked for about 20 seconds when I reseated all the transistors and then slowly went off the screen. Sometimes it works but will always stop working within 20 seconds. The position knob would not bring it back. I'm new to this so all help will be greatly appreciated. I have the manual and I've been reading it.
Sent from my iPhone
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