To recap or not to recap...

Discussion in 'Radio Circuits, Repair & Performance' started by WM4MW, Feb 14, 2019.

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  1. G3YRO

    G3YRO Ham Member QRZ Page

    No, that's a poor analogy . . . not changing the oil in a car would be like failing to regularly clean and lubricate the relays, switches and pots in a rig.

    My Toyota Supra has now done 230,000 miles . . . yet it still has original springs, wheel bearings, suspension bushes, even track rod ends. Are you suggesting they should be changed, even though they show no sign of wear? (sure, on most cars I've owned these parts would typically need changing every 70,000 miles . . . but not if quality components are used)

    I never changed the PSU Electrolytics in my 45 year old Yaesu FL200B amplifier, because they were still fine . . . same goes for the ones in my FT101E.

    Roger G3YRO
     
    KC8VWM likes this.
  2. K0OKS

    K0OKS Premium Subscriber QRZ Page

    Fair enough. Oil changes are more frequent. Not replacing 20 year old electrolytics is like not replacing a timing belt with 100K miles on it. Disastrous results can come from failing to perform such maintenance.
     
    WQ4G and US7IGN like this.
  3. G3YRO

    G3YRO Ham Member QRZ Page

    No that's still a poor analogy . . .

    40 year old electrolytics can be perfectly fine - they are in my FT101E !

    But not changing your timing belt on an overhead camshaft engine that is an interference engine after 80 to 90,000 miles is foolish . . . as belt failure usually destroys the engine.

    If it's NOT an interference engine, it doesn't really matter, as no damage will be done if it breaks. You can just wait until it breaks if you want.

    Not changing electrolytics in a transceiver will rarely ever cause any damage at all, even if they ARE on their way out. (but you can normally tell if they are anyway, as you will get excessive voltage drop on load, as well as ripple)

    Roger G3YRO
     
  4. K0OKS

    K0OKS Premium Subscriber QRZ Page

    Short to ground with no fuse == no transformer. The timing belt analogy is pretty good. A timing belt is a known point of failure. So are electrolytics. Sure you may have a couple radios where they still work. There are some cars where the timing belts still work, but both are doomed to eventual failure. This is simply a fact.

    Caps are comparatively cheap, and the big ripple-laden filter caps are easy to replace. Why risk it? There is simply no benefit to risking it. Anyway, new electrolytics have that new-cap smell, which always brightens up the shack!
     
  5. N7EKU

    N7EKU Ham Member QRZ Page

    Hi,

    I don't think the TS-440 has any big ripple-laden caps in it?

    73,


    Mark.
     
  6. N8AFT

    N8AFT Subscriber QRZ Page

    My 30 yrs fulltime professional radio rebuilder had the pleasure of digging out all of the tar excreted from the cooked power transfomer
    of a nice Collins R-388. He said there was a tar puddle about a 1/4 inch thick on the bottom panel to dig off after he got it unstuck.
    What caused the power transformer to run so hot and utlimately fail? POWER SUPPLY FILTER...
    Why chance an expensive, if you find one, transformer for the relative low cost and time involved to replace that 50 plus yr old component?
    I sleep better now knowing I won't smell that awful stink of my xfrmrs going to the great power supply in the sky. My Viking II was my teacher.
    I have a fulltime self employed Kenwood hybrid specialist that has rebuilt my TS-530s and 830s rigs.
    Part of those rebuilds included new power supply filters as a priority of the technician.
    When you know what fulltime radio pros insist on replacing it's foolish not to take their advice.
     
    Last edited: Feb 20, 2019
    WB5THT and K0OKS like this.
  7. KD8DEY

    KD8DEY Ham Member QRZ Page

    If it makes you feel better, Re Cap and call it a learning experience..
    In the end, it's your money, time, and effort....
    Ymmv
     
  8. K0OKS

    K0OKS Premium Subscriber QRZ Page

    That is correct. Most rigs powered by 12V don't have much ripple because the power supply takes care of that.

    Note that any electrolytic will eventually fail, even without a lot of ripple. However, caps with high ripple, or those that are hot (like in tube gear, or poorly positioned near a heatsink like a voltage regulator, etc. Sadly, designers do this FAR more often than they should.) are the most likely to fail.

    I burned up some 6HF5 tubes when I did NOT notice that an old Mallory cap was actually an electrolytic in a plastic case (it looked like a metal film). This cap went from the PTT line to ground. So when I powered up the rig (on a Variac) it went into transmit. Took me too long to realize that and the tubes were toast. Lesson learned was to check the parts list to find ALL those all electrolytics and replace them in an old tube rig (Swan 500 from 1967). In something that old, and tube powered, I just replace them all.
     
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  9. G3YRO

    G3YRO Ham Member QRZ Page

    No, as a former Yaesu engineer (when the FT101 was a current model), over the decades since then I have worked on dozens of FT101s . . . and never once found any issues with the PSU Electrolytics.

    Furthermore, if there IS ever a short on any of the PSU rails in the FT101, the mains fuse blows instantly . . . thereby the protecting the mains transformer. The only reason I have ever seen someone fry the transformer is where they have stupidly replaced the 3 Amp fuse with a 10 Amp one (because it kept blowing, due to a short!)

    i have also worked on lots of FL2000 and FL2100 amplifiers, which used the same electrolytics . . . again, never seen any need to replace them.

    It seems to be all down to the actual quality of the electrolytics used in any given piece of equipment . . .

    For example, I HAVE known the PSU electrolytics in several of the FT101Z series need replacing (even though they were newer) . . . but I'm guessing Yaesu went over to using cheaper inferior components.

    Roger G3YRO
     
  10. N1OOQ

    N1OOQ Ham Member QRZ Page

    I've mentioned before... I worked for a few years in the service dept. of a company that made boat navigation gear. "Change all the electrolytics" was not a repair technique we used. We had gear back to the 1980s coming in every day. FWIW
     

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