YO-100 with positively charged case!

Discussion in '"Boat Anchor" & Classic Equipment' started by KI7WQH, May 19, 2018.

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  1. KI7WQH

    KI7WQH Ham Member QRZ Page

    Thanks for helping me out, so if I understand you correctly for this application I could swap out the old axials for electrolytic radials as long as the voltage met or exceeded the old ones and the uF was the same? The type only matters when it comes to polarized/non-polarized and in very specific applications?
  2. KA9JLM

    KA9JLM Ham Member QRZ Page

    The polystyrene types need to be replace with none polarized type.

    You can exchange a radial and axial, But you need to be careful about lead length.

    You should have no problem finding the correct caps.

    Does the scope work ?
    Last edited: May 20, 2018
    KI7WQH likes this.
  3. KI7WQH

    KI7WQH Ham Member QRZ Page

    Cool, thanks, just hunted down most of the caps, even the ones that charge and discharge (dont have a capacitor tester yet, its on the way, so I was just using the ohm meter for now) and I upped the voltage on most of them where it was feasible. I've read that even with a tester its hard to tell if they are leaky and figure I should just replace them while I have it open on the bench.

    The scope powers on and I can get a line and move it around and focus it just fine, but since I noticed the voltage problem I didn't want to hook it up to anything to see if it reads the IF signal yet- I also need to get a signal generator! The manual mentions the scope can be used as a standard oscilloscope but it doesnt explain how that is done. I'm very interested in that because some guy found out how to output video to oscilloscopes from a rassberry pi and I was thinking maybe I could make a panadapter with one of the pis I have laying round and my SDR. Hook it up so I feed the IF out of the ft-101 to the SDR and then feed the video out to the scope using the config files he cooked up. It's a pretty tiny screen though so I might just hunt down a cheap green monochrome monitor off ebay and build it into this extra landliner case I have. I think if I found the right monitor (like from one of those old sewing machine sized "portable" IBM XTs) I could make it look like it matched the station! I could also use the pi to do cw and rtty etc.
  4. KA9JLM

    KA9JLM Ham Member QRZ Page

    When you do get a cap checker, Make sure that you discharge them before testing by shorting the leads together.

    Even small caps can hold enough charge to damage your tester.

    Have Fun.
  5. W6ELH

    W6ELH Ham Member QRZ Page


    I'm not an "old salt" like some of the fellows who have been helping you here, but I have been rebuilding vintage gear for a few years now. I have one of the modern capacitor testers, and it is useful, but doesn't tell the full story, as they don't test for leakage. For that, I added a Jackson 591 to my bench, but those are neither cheap nor easy to find.

    Please pardon me if you know all of this, but you may wish to look at "Mr. Carlson's Lab" on YouTube. He has spent a vast amount of time on this topic, but if you search for his tutorial on rebuilding an Echophone EC-1, you'll get some insight into leakage testers. Paul has also designed a low-voltage leakage tester and offered up the plans on his Patreon page.

    Regards... Jim W6ELH
  6. N8CMQ

    N8CMQ Ham Member QRZ Page

    Hi Steven, congrats on the scope!

    I have restored many old boxes by doing a cap and resistor change. Sometimes you can get by with just a cap change, but resistors are prone to failure by drifting out of tolerance over time.

    Rather than measure each component before changing it, I have just bit the bullet and verified the value installed and ordered a replacement. This is especially true with the more complex circuits, swap out the prone to fail components.

    If you are trying to build your trouble-shooting skills, then testing the components before you swap them out will help your learning, but for expediency, I have learned to shotgun the units, change out the components with new, just to get the job done quick and cheap.

    The tubes, transistors and ICs usually do not need to be changed, unless they are damaged by failed components around them. So I leave them alone till I power the unit up for testing.

    Good luck with the project!
  7. G3YRO

    G3YRO Ham Member QRZ Page

    Keep seeing this on here . . .

    Any equipment that has filter capacitors from the Mains input to chassis that ISN'T properly earthed will give you a shock . . .

    It doesn't mean the capacitors are faulty or leaking !

    It is simply the fact that they are Capacitors, so will pass a very small AC current through them (even though it is only 50 or 60 Hz). If the two capacitors are of equal value, the chassis will actually be at HALF mains voltage (if it isn't connected to earth)

    Given how OTT most US regulations seem to be about equipment generally, (compared to ours here in Britain) I am ASTOUNDED that you never had a legal requirement for all equipment to have a 3-core Mains lead !

    Over here, it has ALWAYS been a requirement that anything metal (electric toaster, kettle, lamp, etc) MUST have the metal earthed . . . in fact the earth pin on our standard Mains Plugs is bigger than the two power pins.

    As most of you have probably never seen one of our standard British plugs, you may be interested to see that they also have a Fuse inside - you fit a Fuse to suit the appliance, from 1 to 13 amps. So we have just one standard 240V Ring Main around the house, for ANY appliance.[​IMG]

    Roger G3YRO
    Last edited: May 24, 2018
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  8. KI7WQH

    KI7WQH Ham Member QRZ Page

    Hi Roger, just replaced some (not all) the caps and I still have the same problem so it might be something as simple as grounding the case however this is the first time I've run into something like this even with old electronics (never been shocked by a toaster) and I can't find anything on the internet about people having a charged case (although I can't find much on this unit at all so that's not saying much) - Are you saying this could be normal behavior for this unit?

    The connectors for the antenna input and output and the RCA style jacks on the back all come into contact with the case (the outer portion of the plugs) perhaps they intended for the unit to ground out through that pathway? Or is that totally wrong?
  9. KA9JLM

    KA9JLM Ham Member QRZ Page

    You should put in a 3 prong plug.

    When that unit was built the AC cord only had 2 prongs, That unit has a transformer so polarity did not matter.

    Antenna ground is not the same as AC ground, But close if your antenna ground is bonded.

  10. G3YRO

    G3YRO Ham Member QRZ Page

    As I keep pointing out on threads about this, you will ALWAYS get a shock if the chassis/case isn't grounded - this is NOT due to there being anything wrong with those capacitors !

    The capacitors from Mains to Chassis are De-coupling capacitors - they are there to get rid of RF !

    So you won't find them on a Toaster, etc, only on rigs. (The reason a Toaster should be grounded is in case there is ever a short between the live wire and the casing . . . rather than you getting a bad shock, it would then blow the fuse.)

    But the point is that the rig should have a 3-core mains lead and plug, so that it is grounded as soon as you plug it in the mains. (and not relying on any external plugs and cables to ground it.) So as it doesn't have one, replace it with a 3-core cable and plug.

    Roger G3YRO

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