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I've got a slightly toasted R1071 as well, and a supply that won't come up. Initially, I could hear a ticking sound, U1030 would come alive, drive signals were reaching the drivers, and the supply

Ross, Is there a suggested repair for the plastic bushing? Is there some preventative maintenance that can be done? -- Jeff Dutky

Got the voltage stabilized by replacing the 2N4275's and the 2N4122's with 2N3904's and 2N3906's on the horizontal amp board. Voltages are out of whack however I don't have that out of line voltage I

Yup. That is the motor. The failure mode of them is that the heat generated by the shaft turning over time melts the front plastic bushing and the shaft wobbles. Sooner or later, it freezes and blows

I think the + output is a positive voltage with respect to gnd and the - output is a negative voltage wrt gnd. That's what makes the measured voltage, with the DMM connected to the + and - terminals,

Jared, RF diode cavity? I did some googling for that and didn't come up with anything very helpful (but a bunch of interesting sounding stuff about laser diodes with external tuning cavities), then I

Here is a link where I bought one of these motors about a month ago: https://www.surplusgizmos.com/Siemens-1AD3001-0A-DC-Motor_p_3144.html. He's selling them as-is, but the one I got works and looks

Pat, C804/C808 could be leaky causing the 7V at G. Put in A position. If you still get 7V at that point, that makes the two condensers more suspect. You could also have a bad transistor (shorted from

According to Jared's video those capacitors charge up to about 0.3V and are compared to the divided battery voltage. Of course there is also the 1uF caps that would then also charge to 0.3V, since

This is correct, they are feed-through capacitors from the RF diode cavity to the rest of the circuit.

Now have partial sweep about 1/4 by putting in a 2N3906 at Q834 and triggering OK but am still stumped why I am getting a good .7V and good signal at connector I but still getting 7 volts with no

I believe I am getting close as I swapped Q814 and Q824 and the problem swapped as well and believe this would be a good start. Any suggestions on finding any 2N4275's?

Perhaps feedthrough capacitors. Ozan

Pat, C759 should be left alone unless bad. The 1mfd decoupling tantalums can be the R82 series film types. Mouser has these 80-R82DC4100DQ60J. You can add ULD types in a couple of places to give

Jim, I have a later version of my simple peak detector, where I actually did the math to see what size cap I needed for a given output frequency, and I ended up with 2 nF in parallel with 1 MΩ

A 1N4148 should be a decent sub for the 1N4152. --Cheers, Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 http://www-smirc.stanford.edu

John After doing a little more probing it looks like the signal ends at D861 1N4152. Any ideas on what to replace it with? I have some 1N34, 1N60 and 1N4148's is all I have on hand. I will try a

Sorry John as I did the connectors last and did the others inside of the board first. Pat

Hello Mark and John First off Thank you Mark and John and sorry for the late replies as I only get an hour or 2 a day. So far the latest date codes I found on some of the caps range from 68 to

I tried your idea of using a diode, 200 ohm resistor, and capacitor and it does work. I'm not sure what kind of diode I used, I just picked an old unmarked one from my parts bin. I did not have a