Good afternoon folks, I¡¯ll try to make this brief but still include as much pertinent information as I can. I have a 465, non-A or B model. I¡¯ve spent a few evenings replacing a few Ta¡¯s and pulling the Vertical attenuator board and carefully cleaning up all the switches and rotaries, alcohol on switches, and D5 on the rotaries. But before I started anything I noticed that the delayed sweep did not function as I expected. I wanted to wait till the machine was working in other regards before I started on this issue.
Here¡¯s what¡¯s going on, firstly, I am not very familiar with the internal workings of Delayed Sweep. The extent of my experience is only from the ¡®Knob¡¯ side and using it in viewing the structure of an NTSC video signal and other such complex waveforms, but lately, I've had little need for it. That said, I still want to make this 465 work as expected, and a working delayed sweep is part and parcel of that end. I believe I understand the difference between ¡®Hold-off¡¯ and ¡®Delayed Sweep¡¯ for what that's worth.
Here¡¯s what I¡¯m seeing; first I wanted to rule out a mechanical control, so the 10 turn R1110 appears to function as it changes the voltage on Q1042 from 2.4 volts to 12 volts, position dependant.
In the ¡®B DLY¡¯D¡¯ mode and the Delayed Sweep knob pulled out and moved a few clicks CW I see the auxiliary time base sweep somewhat dimmer but much faster than the main time base waveform to the left. R1110 the Delay Time Position has no effect.
In the ¡®A INTEN¡¯ mode, all I see is the A or primary sweep, there is a brighter section and a dimmer section depending on where the delayed time pull knob is set but there is no difference in waveform between the brighter and dimmer trace. Again, the Delayed Sweep Position has no effect.
In the ¡®MIX¡¯ mode, what I see is the faster auxiliary time base or B sweep without any view or intensification of A. I hope I have that description correct. The main takeaway is the 10 turn pot R1110 has no effect on anything. For what it¡¯s worth, the ¡®TRIG¡¯ button is in ¡®AUTO¡¯ and all other functions work fine including proper trigger functioning.
My understanding of the subsystem involves a secondary or auxiliary time base that lets the user view in closer detail a segment or a ¡®magnified¡¯ view of a more detailed waveform, much like the ¡®Zoom¡¯ feature of today¡¯s digital scopes. However, I wish I knew more about how this sub-system works. I know a delayed time base is appended to the primary time base by a user-selected period or delay. Sadly knowing how to drive a car doesn¡¯t make me a mechanic. <Grin>
I¡¯m really not sure where to start ¡ it¡¯s on the bench as I type if anyone might need additional info, I¡¯d be delighted to dig in deeper. I have the OEM Tek manual and the necessary TE at standby. Interestingly, there¡¯s a great video of a 465B tear-down and switch cleaning. Unfortunately, my 465, not being an A or a B, was quite a bit different but I still gleaned some good NFO regarding pulling out the attenuator panel. Still, it was an all-afternoon job. At least now all the vertical positions are stable now. This is a nice scope with a sharp trace and plenty of brightness. It really does deserve to have everything functional.
Thoughts, comments, most welcome~!~
Michael - AF7U