On Sat, 19 Jan 2013 18:59:59 -0500, "tm"
wrote:


"John Fields" wrote in message
.. .
On Fri, 18 Jan 2013 16:36:30 -0500, "tm"
wrote:


"John Fields" wrote in message
...
Hello,

I have a Tektronix 465 which is perfect in every way except that the
horizontal trigger has gone belly up and the trace free-runs no matter
what.

Clue, please?

Thanks,

--
JF


Bad tunnel diode?

Do you have the service manual?

http://bama.edebris.com/manuals/tek/465(2)/

---
Yes
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Can you trigger the B sweep?

---
Yes.

--
JF

The TDs are Ge and heat will kill them. Use forceps against the body to
solder them. Do you have access to a curve tracer? If so, check the TDs for
the A sweep. I usually check them in circuit. I think they are 4.5 ma or 10
ma diodes.

---
OK
---

Feed in a test waveform to the external trigger input and see if the trigger
view works.

---
It does.
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You do have it in norm mode vs auto, right?

---
In AUTO it free runs, no matter what, and in NORM it does nothing, no
matter what.
---

Can you line trigger?

---
No.

--
JF