Have a look here: http://search.murata.co.jp/Ceramy/image/img/A01X/RDEEDCD1.gif if you go for an 100V X7R, up to 10V there's no significant change of capacitance with DC bias. Did I mention that

Davids advice caused me to recalculate a voltage but I reach the same conclusion as before and the same as David. The voltage across C1291 could reach 7 volts and the older layout oriented polarized

My guess is that in the 80's there weren't many affordable ceramics in the 1-10uF range, and the film ones with such capacities were rather huge. These days you can find inexpensive X7R ceramics

When the 7904 won’t work in Chop Mode check for a missing Chop Drive Waveform which is on pin A5 and Chop Common which is on pin A6 of the interface board. Without it you can only alternate. Or try

My schematics do not agree with this description so the precise numbers I use may be different than yours. But my advice should still fit your case. I will describe the difference, then why the

I suspect connectors, sockets, and voodoo.

If you use a trimmer potentiometer, then it will take 1 or more fixed resistors to lower the sensitivity. The unbalanced Nuvistor front end does not have the best temperature stability. It looks

Picked up 2 7904's the other day. B15xxxx with a bad interface connector and FF in the calibrator circuit, and B25xxxx that is possessed. No matter what vertical mode I selected I got Alternate.

I usually reverse engineer from the schematic to decide what part would be best. C1291 and C1292 may be polarized but should be low leakage. They operate with a voltage of 7.5 volts across C1291 and

Ah, good to know. I will take a look at the 454 manual and maybe just find a fixed resistor value that gets it closer to zero. On my 453 it seems reasonably constant. Step attenuation balance changes

The 454 added an adjustment (R334 in the middle of schematic 4) for the vertical amplifier balance which could fix this. Tektronix apparently used it to prevent position shift in ADD mode but I think

I'd use a halogen or projector lamp rather than a fuser lamp. They should run with a much higher filament temperature and have a greater cold/hot resistance change. It should be only a

I found suitable and relatively inexpensive, less than $20, panel mount ones from Newark but I had to spend time going through datasheets to do it. They were panel mount toggle switch style

As long as one observes the max rated ripple current and voltage, there's no harm done through replacing polarized caps with non-polarized (bipolar) ones. So if in doubt use BP and live happy.

There are quite a lot of 3.3uF/400V available from digikey, mouser and newark. If you're looking for the longest life, the Rubycon LLE (digikey has stock) is the one. Take care there are 2 versions in

That too. I have some DIN rail ABB breakers in my junk store of 2A 4A 6A 8A 12A... any of those would be fine for this kind of app. I have a photo catalog of my attic and store room junk. Maybe I

Unless you leave them in the fuser....or just mounted in the fuser roller... I have an obsolete HP 8550 fuser for sale on craigslist. Maybe I'll keep it instead...:-)

Thank you all for the suggestions regarding a 2N3251 substitute for my 453. Regarding the 2N3251 datasheet, it turns out that I had managed to conflate the poor availability of 2N3251 transistors

Hi Rob, Assuming that your power supply was working correctly prior to the recapping, then you should replace with the same capacitor types that you find installed in the unit and ignore the Tek

I looked into this earlier during the discussion because I also wondered how expensive the power devices would be. If you use a thyristor as a control element then turn-off (commutation) only occurs