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Discussion in 'Radio Circuits, Repair & Performance' started by WA6MHZ, Mar 13, 2013.

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  1. AF6LJ

    AF6LJ Ham Member QRZ Page

    Don't forget the lurch to the right and, the sound of the alternator belt slipping when heavy current is being drawn.
    I thought those things were really Cool.
  2. AF6LJ

    AF6LJ Ham Member QRZ Page

    Let us know how it goes....
    Maybe a FET
    Maybe a bad output diode....

    Maybe throw a bigger heatsink at it.
  3. KO6WB

    KO6WB Premium Subscriber QRZ Page

    And BTW in the case of heat sink grease (compound) more is not better.
    Just a thin coat is more than adequate.
    The FET's are easy to test. Not a lot to the booster. Replacing every part
    except the toridal transformers shouldn't take long. Not the best of a
    troubleshooting approach. Getting just that one component is a good
    Seems like it should be up and running in short order.
    Good luck Pat
  4. KM1H

    KM1H Ham Member QRZ Page

    Is it my eyes or do a couple of the caps have bulging tops?

  5. KA9JLM

    KA9JLM Ham Member QRZ Page

    I seen that, thought it was the view.

    The caps in a switcher need to be low ESR. Would sure be worth measuring.

    As well as the oscillating frequency to make sure it is correct.
  6. WA6MHZ

    WA6MHZ Premium Subscriber QRZ Page

  7. KA9JLM

    KA9JLM Ham Member QRZ Page

    Are you charging a battery with it ? Why would the battery be connected to the output ?

    The White Monkey Poo heat-sink compound works best.

    It looks like the TO-220s are mounted so close to each other that a outboard heat-sink(s) would be nice.
  8. AF6LJ

    AF6LJ Ham Member QRZ Page

    The lower left cap looks suspect.....
  9. WA6MHZ

    WA6MHZ Premium Subscriber QRZ Page

    All the caps are checked with no problems. None are bubbling up or such.

    Yes, am charging a Gel Cel with it. The reason is that the Charging voltage to the Gel Cel comes from the Fuse block of the car, and by the time it gets to the battery, is too low to adequately charge the battery. It winds up being 12 volts or so, so the Gel Cel never gets really charged. It needs around 13.8VDC to properly charge it.

    The Battery Booster is rated at around 25Amps (with 30A power fets) and, I have placed a power supply on the gel cel when it was discharged and never measured over 10A being drawn by it. So the Battery booster should be loafing along. Once charged up, the Battery booster just applies a trickle charge to the Gel Cel. This worked perfectly for many months before this failure occured. The output is pulse width modulated, so there should be no hard current failures with the FETs. I ordered 2 pairs of semiconductors, and will install one set. (keeping a backup set). If it blows again, then there is a problem in the design of this lashup.

    I was already ragged big time on my design because I did not run a wire to the car battery to the rig. That is why there is a Gel Cel to run the Icom 706. The battery booster is switched via Relays when the car starts and the circuit enabled over to the OUTPUT of the Gel Cel to apply 13.8V to the Icom 706, which is needed for proper operation. 706s FM on transmit at 12V. Despite all the naysayers, this system has worked very well until this failure. I cannot get a wire through the firewall as many say I can. But there is NO grommet or passthrough that gives access between the underdash and engine compartment. I have heard of no one successfully doing it on a Town Car. It HAS been done on Crown Vics, but not a Town Car. One suggestion was to run it UNDER the car but I didn't like that idea as if the car bottomed out, it could shear off the wire insulation and cause a fire. So this system works great, though it takes up all the drivers side rear seat foot room with the battery case. But since I never have any passengers, not a problem.

    Secondly, if U leave the radio on accidently, U can come out to a DEAD starting battery if U use the Auto battery to run the radio. With my system, there is NO CHANCE WHATSOEVER of the starting battery ever running down. Town Cars are smart and turn off the headlights, interior lights and any other possible current drain if they are left on. Starting the car is the MOST IMPORTANT feature of the car. If the car doesn't start, it is time to call TRIPLE A and a TowTruck. When I am on the road to Dayton, I am very snakebit about having a starting failure. My silly wife used up one of my Triple A auto tows with the baby boy's Charger, so I only have ONE chance left before I am stuck with the full tow bill. And when I am in Oklahoma or New Mexico, where it is 100 miles to the next wide spot in the road, I have to put FULL TRUST in the car to keep going and always start.

    Anyway, I am waiting on Digikey now to deliver the parts. I had it sent UPS Ground cuz they wanted $16 shipping for 3 Day and some incredible amount for NEXT DAY delivery. It turned out to be $8 shipping as it was. And that is for $10 worth of parts! Sucks. Delivery is speculated for sometime next week.
  10. AF6LJ

    AF6LJ Ham Member QRZ Page

    Must be an optical illusion making that one cap look a little bloated....
    Your system works its just surprising the firewall is that used up that a place to locate a hole and grommet cannot be found.
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