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Thanks Mike. I think I'm thinking too hard about this. That makes obvious sense. Cheers Kevin KN4M TekScopes@...> wrote:

Use you dmm on the existing capacitor to verify the correct polarity BEFORE attaching added capacitor. Mike N2LYM

Hello everyone! I'm searching for two parts for my sampling scope (Tek 11801): 1) 2x knob for sampling plugin (part# 366-0673-00 (KNOB:O.096 ID X 0.24 OD X 0.299H) 2) 1x empty plugin slot cover

Makes sense. I'll report back my findings as soon as I locate a cap and solder it on.

Thanks for bringing the image issue to my attention. My apologies to the group.

You may find the positive side for your temp. C. by switching the 'scope on and measuring DC voltage across C4439. The plus side of the cap. goes where the more positive voltage on C4439 is seen

Hey Kevin, I don't think the Yahoo forums like photos in messages. You can create a new photo album and upload to that. Siggi

You need to read the the wiki article, and message #112514 to get the background info and update. Then look at #96664 for the best implementation that I have seen, in my opinion. Ed

Let's try this one more time. Sorry for the bandwidth...

Sorry, here is the image [image: voltages] [Non-text portions of thi

The photovoltaic MOSFET approach would work of course. Current is more than enough but regulation is compulsary at >13 V open circuit. The sampler diodes in reverse bias hardly allow any current

That's what I figured. I will look in my junk box for an old power supply or some other electronics gizmo for the 100 v cap. Assuming I find one in the next day or so, I am now trying to determine the

Another possibility on the photovoltaic approach is Vishay's LH1262 photovoltaic MOSFET drivers. It has two photovoltaic generators in a DIP or SOIC package. You can get a minimum of 2.6uA each

Kevin, Don't try a 470 uF 35V cap. unless you're looking forward to an early firecracker party a few seconds or minutes after switching on... Raymond

Kevin, All PC Power supplies contain at least one large electrolytic cap. with several 100 Volts of working voltage and at least several 100's uF capacitance. That will do the job. It doesn't matter

Thanks for the offer Tom. I can, of course, go to mouser, but I'm not too keen on paying shipping for such a small part, especially if I will have to go back to that well for additional parts. I will

Eureka. I found it. Thanks Raymond. It must get confusing helping so many people out with different scope problems. I did in fact find C4439 in the service manual. Now I have to find a 100 v cap. I

The difference of 0.1 volts is insignificant as far as risk to the sampling gate diodes but as Raymond points out, zinc-air batteries are a poor choice because of their short life once activated. I

I wouldn't consider zinc-air batteries a good choice for this purpose. Zinc-air batteries have a relatively long shelf life unopened but once opened (activated), they discharge rather quickly, even

Hi Kevin, Raymond is absolutely correct, I did use the wrong schematic. The cap I suspect is bad is C-4439. And I agree with his comment about what to try. If you really can't find a cap easily, let