I and my father was "gifted" a Tektronix 475 (Serial no. B289252) on the condition that we fix it and return it. As such we have no knowledge of prior owners or repair work that was either attempted or completed.
When hooking the scope up to it's own test post, two dots are seen and can be moved both vertically and horizontally with each respective position knob. When nothing is connected, there's a single dot.
We believe the problem lies with a sweep generator, but this scope is more complicated than others that we've repaired in the past. The 475 manual we have does not have waveforms or voltages indicated, so we've been using the 475A manual and hoping that the two are similar enough. This is not helped by the fact that in some cases the 475 manual appears to not exactly match our scope; incorrect part numbers or components in different spots on the PCB than is indicated.
Does anyone know where we:
- Can find a 100% accurate (to our scope model) manual featuring waveforms and voltages?
- Even begin to diagnose this issue? Probing without understanding the circuit has us narrowed down to something, but we don't know what we're looking for.
- We're pretty sure the problem lies just after U720, as we stop seeing waveforms. However, we're using other scopes that we repaired ourselves to diagnose the issue, which does not fill us with confidence.
New to the forums, we did search before posting but other 475 issues seemed unrelated or unanswered. Thanks for y'all's patience with us!