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Galaxy saturn ept360014b vr16 low power will not adjust

Discussion in 'General CB Services Discussion' started by That_guy_in_wv, Apr 23, 2020.

  1. That_guy_in_wv

    That_guy_in_wv Active Member

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    Have a nice galaxy saturn that looks like very few have been in, I was tuning up the radio and doing an alignment and noticed when trying to set the radios low power with vr16 there was no difference when turning the vr with the rf power knob at any setting the radio keys rf power all the way down 2 1/2 watts and swings 20 watts, on am and sideband, also vr13 works fine. I've had quite a few saturns in and the 2166 and two 2312s usually do almost double that. Not sure what's stopping the vr from working but I'm sure it's probably the low power vr not working.i change the vr still nothing, I've looked over the board for cold solder joints and can't find any. R241 has a 1n4841 diode in line with the band towards the finals is all I can see that someone might have put in other then that I'm stuck again.


     

  2. Robb

    Robb Yup

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    Take out the 1n4148 and put the resistor end back in the hole and solder.
    Check to see if TR32 had been removed (probably); replace with a 2sc945.
    That should straighten out modulation issues.

    You might start by checking the 50mA for the driver trans, then the final trans should be 50mA each for a total of 100mA.
    For details, see:
    http://www.cbtricks.com/radios/galaxy/dx99v/dx99v_trans_adj.htm

    There is interaction between the low power VR and the high power VR; might check there first, since someone might have monkeyed with them.

    In addition, the transmitter tuning coil chain (L43, L44, L42, and L40) may also need re-alignment.

    One of the finals bias VRs may have been turned down.

    Anyway, that should give you something to start looking at.
     
    #2 Robb, Apr 23, 2020
    Last edited: Apr 23, 2020
    NZ8N likes this.
  3. 9C1Driver

    9C1Driver Sr. Member

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    It's probably set so with the RF power all the way down it will run with a small amplifier well. What's the hi dead key? What's the peak swing when wide open? I would not want to wind one of those out too far or the power supply will fail sooner then later. Since it is a Galaxy by cranking it up too much it will probably warble on SSB.( to go along with the drifting lol ) The power supply won't be able to keep up.
     
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  4. 999

    999 Well-Known Member

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    It looks like the variable ties into R238 at VR13. VR16 is on the other end or the circuit. It's possible that VR16 was bypassed completely taking both it and the front VR out of line.

    [​IMG]

    [​IMG]
     
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  5. nomadradio

    nomadradio Analog Retentive

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    I thought the 'minimum carrier' trimpot was on the small flip-switch circuit board, and not on the main pc board.

    Can't remember the callout number, but it's near the rear of the High/Low flip switch board.

    73
     
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  6. That_guy_in_wv

    That_guy_in_wv Active Member

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    I'll try to see what I can do when I get home later this evening and thank y'all for the help its appreciated.
     
  7. That_guy_in_wv

    That_guy_in_wv Active Member

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    The dead key low is 2.5 watts and the high is 5 I don't like setting them higher then 6 and will modulate up to 20ish
     
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  8. That_guy_in_wv

    That_guy_in_wv Active Member

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    Hey Robb, unless I'm checking them wrong the driver and both finals are pegging my 250 ma scale on my analog meter on dc. Ground on the right leg and positive in the center right? It's the only way I'm getting a reading in receive mode the same as when keyed with no modulation. Over 250ma would have already fried the finals right? I must not be doing it right lol
     
  9. That_guy_in_wv

    That_guy_in_wv Active Member

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    Sorry Robb didnt see the link, I didn't know cbtricks was back online, nice. I checked the driver bias and final bias. The driver sets fine with vr11 but the final bias vr20 is the only vr that works on the finals. Vr10 makes no adjustments no matter where its turned, thus why I have only half my wattage coming from the radio. I also removed the "swing mod" someone put close to the 2sb754 that I removed and replaced with a 2sb827 and replaced both audio amps and regulator with the 1869s not sure the 2sb754 would have been enough for dual finals. Tr32 was never removed. All I have so far y'all and again thanks if y'all could maybe point me in a direction on why vr10 does not work.
     
  10. Robb

    Robb Yup

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    SSB mode only mic modulation set to zero; not AM mode.
    Key the mic and turn either vr10 or vr20 until the mA goes down; proceed in that direction until it goes as low as that vr will take it. Go to the other vr and do the same for it. Unkey. Key it and make sure there are no mA showing. Then, re-key the mic and go to either vr10 or 20 and turn it up s l o w l y until it reaches 50mA . Unkey. Then re-key the mic and tune the other vr until you see 100mA. Done!
     
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  11. That_guy_in_wv

    That_guy_in_wv Active Member

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    Thanks Robb, that's how I tested them. Vr20 set to 50ma and also the driver vr11 also set to 50ma test leads between tp7,8,9 where they test with short board removed and on usb and when trying to set vr10 I have no adjustment like it's not working like the low power vr.
     
  12. Robb

    Robb Yup

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    Is that a dual final radio?
    If so; then it will have vr10 and vr20.
    Both vr10 and vr20 have to be adjusted.
    Each final transistor has a bias adjustment.
    VR11 is the DRIVER bias adjustment; not the final.
     
  13. That_guy_in_wv

    That_guy_in_wv Active Member

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    Vr11 adjust the driver like it's supposed to, it is a dual final with one 2166 and two 2312s. Vr20 will move the milliamp meter and is set to 50ma but vr10 does nothing.
     
  14. That_guy_in_wv

    That_guy_in_wv Active Member

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    I tested vr10 with an ohm meter and it shows the resistance moves when turning the vr but doesnt change the miliamps from the 50ma I set vr20 to.
     
  15. Robb

    Robb Yup

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    There is your problem!
    Gonna have to thrash thru the parts in the VR circuit to find the problem.
    Might be a bad solder joint, VR10, or the MV1Y diode; be my first guesses.

    Annotation 2020-04-23 232750.png
     
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