https://nepp.nasa.gov/files/29192/NEPP-TR-2018-Teverovsky-T22-Capacitors-TN52048.pdf -----Mensaje original----- De: TekScopes@groups.io [mailto:TekScopes@groups.io] En nombre de Chuck Harris Enviado

Using the two-probe method that Mike suggested is the usual way of making a differential measurement (when expensive diff probes are not available, or when the voltages are too high for them). One

Not totally the case, Albert. As I said, the instability can be present after warm-up and can be stopped or induced by "wiggling" the Time/Div knob. Specifically, if the delaying or delayed time-base

That type of capacitor is a wet slug tantalum capacitor, and it uses sulfuric acid as its electrolyte. Over time, the positive lead gets etched away, and the acid leaks out. Lots are starting to

During trouble shooting, I've found several bad 50 uF at 25 VDC radial lead (not SMD!) on the first few boards I pulled for inspection. All of those caps showed severe leakage and many had open leads

Hmm, good info. I think I probably have a late firmware then, it had the earthing recall fix already done too, so it was post recall as well. I guess I'll leave this as it is unless something turns

Hi Colin, Since most of the problem disappears after warming up I guess it's more like a semiconductor issue. Do you have the model with "Alt Off" at the ccw position of the TRACE SEP knob, S/N

Thanks for the info, guys. I have now located where these switches go, but I am unclear as to what their functions are. Perhaps I don't really need to know, after all. I am still perplexed by the odd

O.K.! Thanks to everyone for the comprehensive answers, very instructive to me! Undoubtedly the driving circuits of the 7904 and 7804 CRTs are completely different and this could partly explain the

I would use a low Tempco metal film, say 15 to 50ppm. The only reason I can think of using WW in that location is that carbon comp and WW were the primary choices when that scope was designed, and

Easy and cheap enough to get a pump sprayer bottle from the store, and fill it with IPA. That is what I do when I need to flood a circuit/switch/keyboard with IPA. -Chuck Harris Colin Herbert via

OK, so the existence of spray-can IPA is new to me. Perhaps I should see if I can get it in the UK, but it is cheap enough anyway and I apply it with cotton-buds, tissues or slivers of paper,

The choice of wire-wound was probably for temperature stability of the -100 volt power supply. Since R617  forms a voltage divider with pot R616 and R618, both also specified as wire-wound, the

The description says: "Tektronix Oscilloscope from the 1960s or early 1970s complete with rolling stand and leads. When I plugged it in the lights came on and the screen works. As far as it working

Thanks for your feedback. Whilst I admit the specific tin I've just used does only have "Ambersil Electronic Safety Solvent" written on it I have nevertheless used it extensively for years. It has a

Hi, Colin, IPA IS available in spray cans e.g.

What's immediately jumping out at me is that you have a 7904A with a 7A26.  You can put a scope probe on channel 1 to the positive DC output, and the scope probe from channel 2 on the 41v test

The rule of thumb when isolation is required is "Don't isolate the instrument - isolate the DUT." Plug the Motorola supply into an isolation transformer - a true isolation transformer like my RCA

Hi Mike, This is where it pays to have a 7A13 Differential Comparator and a P6055 differential probe set if you are going to see some high frequency signals (DC to 110MHz) when you do

Mike: As a suggestion:  Use the 7a26 with two x10 probes.  Set the 7a26 with "DISPLAY MODE" set to "ADD" and with "CH 2 POLARITY" set to "INVERT".  Connect the two probe ground leads (or