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Kenwood TS-2000 problem

Discussion in 'Radio Circuits, Repair & Performance' started by KC4UMO, Apr 26, 2015.

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  1. KC4UMO

    KC4UMO Ham Member QRZ Page

    Today a guy called me about a 2000 for sale, so went over and bought it for a decent price. He did tell me it was a "tech special".

    The problem was he lost receive and looked at his amp meter on the power supply. It was indicating around 20 amps or so. Before he shut it off it blew a fuse. I got it home and just wanted to verify what he said so I installed 2 2 amp fuses. Pressed the power button and the display came on and about time it got to the "HELLO" splash it shut down. I checked and it had blown the fuse.

    During this time I noticed the power cord did warm up, along with the rear of the rig. Not wanting to do it again and risk doing more damage I will next tear into this rig tomorrow.

    It almost sounds like it goes into TX mode when it comes on. But that is just a guess.

    Anyone heard of a problem similar to this?
     
  2. AC8AC

    AC8AC Ham Member QRZ Page

    ive never herd of it but I would disconnect the final amplifier section and power it up with low amp fuses . people have a tendancy to try to load up a 20" antenna on 160m puts the final amp section threw some extremely high voltage till the protection circuits fold it back

    ive never seen a ts 2000 with any sort of rf stability problems
     
  3. K9ASE

    K9ASE XML Subscriber QRZ Page

    It's been awhile since I've had my TS200. Maybe another owner will speak up, but doesn't the fan cycle at start up?
    Could this circuit be where the issue lies. As I recall they have a pretty robust fan.
     
  4. KW4EK

    KW4EK Ham Member QRZ Page

    No fan will ever draw 20+ amps -- the fans typically used seldom draw much more than 0.5A (and often closer to 0.15-0.25A). It takes time for a fuse to blow at moderate overload levels (anywhere from seconds to minutes depending upon degree of overload) as fuses are thermal devices and they take awhile to get hot enough to melt their fusible link.

    First rule of troubleshooting is to always attempt to simplify the problem and isolate the fault, especially when the device has a modular construction. When a device is not modular then you start isolating by pulling critical parts inline with certain parts of the circuit and/or isolating power busses. If you can find a single board, or especially component, that when removed also removes the problem then you now know that the problem most likely lies either with that board, or component, or something that follows that board, or component. In this case the amount of power being drawn yields a possible clue as it seems to be suddenly drawing a level of power that would typically be expected from the final power amplifier stage, and a shorted transistor, or its driver (or even a capacitor), in this stage could very easily result in such a power draw -- this is a clue that this should be the first thing to be isolated as there is a good chance that the problem will be found somewhere in this stage.

    Good luck in repairing your new radio! These sorts of problems, as bad as they seem, are often clues to relatively straightforward faults that often lend themselves to reasonably inexpensive repairs, so the odds should be very much in your favor.
     
  5. KM4FVI

    KM4FVI Platinum Subscriber Platinum Subscriber QRZ Page

    My TS 2000 , when turned on, will power up and go right into receive mode with no fan running unless the rig gets hot! I would go right to the power supply section of the radio and look for a short.

    Frank
     
  6. KC4UMO

    KC4UMO Ham Member QRZ Page

    Could not sleep this morning so I came out to the shop and opened the rig up. No signs of damage that you can see.
    I have 12.9 ohms across the power leads. Both directions. The 4 power wires go directly to the final unit then powers rest of the radio.

    I have the SM on PDF and the radio came with 4 fold out paper schematics. That will be a big help :)

    Going to start the isolation process and will post back my findings. Most issues I have seen the 2000 has been solder joints that stop both TX and RX.

    Thanks for the replies.
     
  7. N9ZDZ

    N9ZDZ Ham Member QRZ Page

    maybe try wiring in another power supply direct and see if it blows that fuse if it don't then you know its the internal ps
     
  8. N3DT

    N3DT Ham Member QRZ Page

    Fan on my 2000 does not come on with start up. Starts with hello for maybe 1/2 second and goes right to where it was last. Good luck, I'll be watching this one.
     
  9. KM4FVI

    KM4FVI Platinum Subscriber Platinum Subscriber QRZ Page

    Me too!

    Frank
     
  10. KC4UMO

    KC4UMO Ham Member QRZ Page

    Looks like the problem is in the final board. 2 black and 2 red wires go from the rear 13.8 jack directly to the final board. When doing a ohm check across the red and black it shows 13 ohms. That is way to low. Should be much higher.

    I disconnected everything coming off the final board all but the external supply wiring. I still have 13 ohms. There are several regulator transistors laid flat on the board. I found one that shows 13 ohms on the output leg. Next is to lift that leg and see if the problem is still there. But first will trace this on the schematic to verify.

    I also noticed several MOV's on the board that will need to be checked. I looked at several capacitors and did not see any that are swollen. Will have to remove the final board to check ESR on them.

    Since the 13.8 comes from the rear jack directly to the board there is really no way to power the radio with the final board disconnected.
    But for now it's off to my daughters for dinner.
     

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