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I would like to thank Bob for the video! So, thank you Bob! Well done! I am replacing the following on the A1/A5 board related to the HV supply: C850, C851, C881, C882, C883, C885, C887, R888

Here is the video: https://youtu.be/orV2HX5YL5E -- Bob Haas

Bob, Which tantalums are you having to replace under the A5 board? Barry

Bob, Looking forward to the video! Thanks! Those capacitors are actually on the A5 Aux board. I had that board out for cleaning and inspection. I did not check the capacitor values. I've been

The DC Restorer caps are C881, 2, 3, 5 and 7. They go between the main (A1) board and the HV auxiliary (A5) board. In my experience, they are more likely the problem than the diodes on the A5 board.

CR884 and CR885, they are on A5 board. Regards, Ignacio -- Este correo electrónico ha sido analizado e

When I get the vertical amplifier's damaged IC replaced (and the problem is still there), I'll add a picture in the group page. Thanks, Barry - N4BUQ

Hi Barry, Is there a picture of how the distorted characters look like? Ozan

Mark, Thanks for the help! Greatly appreciated! I am thinking the Bias pot is R873, its labeled Beam. Last week I found that pot had come apart. No trace. If I pressed down on that pot the trace

At issue is that the stretching occurs even when the trace is not extended past the top or bottom graticule. It isn't horrible but quite noticeable. I have another 7704A, two 7603s, and a 7514 and

Harvey, I think we are talking about different things. Your suggestion was to view the V en H signals of the faulty 7704A on another scope, with the other scope in XY-mode. The bright spot is on the

I looked back through this thread, and I don't know what the deal is here, so please forgive if I've missed something. In the OP, I think it was an issue about the readout distorting severely when the

Barry, The resistors are: R3439, R3442, R3493 and R3494. The the 510 ohm resistor, R3494 should be 1/2W. These are on the readout board. From what you said happened to the resistor, transistor and

Mark, I'm not sure which are the 2400 and 1500 ohm resistors. I don't see those values on the readout or the vertical amplifier board. As for the character height, I reduced R3468 to what I believe

Barry, The 2400 ohm and 1500 ohm resistors should be 1/2W. The former and one of the latter are in the upper left of the schematic and the 1500 ohm resistors to the two transistors to the outputs. I

Barry, Look at the crt circuit in the schematic. The diodes can/should be replaced with 1N4937 and I strongly suggest replacing R888 with a Vishay VR37 series 22meg resistor. That carbon will be out

I am clearly out of my league... How do I find the "intensity DC restorer" circuit? Thanks!

Disable the high voltage, unplug the CRT, certainly defocus the CRT, If there's a fuse in the HV supply, you might try removing that. The problem is (on a bright spot), the density of the electron

Harvey, Regrettably this is almost impossible without blanking the (otherwise extremely bright) central dot. It would require the use of one of the control signals (perhaps Z-axis Inhibit) in the

If the intensity control doesn?t work the blanking problem is a consequence of it. With a high degree of probability one or more diodes of the intensity DC restorer are leaky. Since testing it is