Troubleshooting a Vector Research VR-5000 - No sound

Discussion in 'Solid State' started by bigberts, Mar 29, 2014.

  1. bigberts

    bigberts New Member

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    I recently purchased a Vector Research VR-5000 Receiver off e-Bay. I bought it for sentimental reasons since I had one in college. If I totally screw it up I did not ruin a classic Pioneer/ Sansui/ etc...

    I am pretty new to vintage equipment and have very modest electronics skills.

    Here is what I have done so far.

    1) Read about these issues on this forum
    2) Cleaned the unit inside and out
    3) Used contact cleaner on all the pots (did not touch the tuning capacitor)

    4) Powered it on.

    When I power it on I get lights, but no sound out of the speakers or the headphone. According to the diagram in the top, the speaker relay protects both the speakers and the headphone jack. Speaker relay looks like it is in good shape, but does not engage.

    Speaker Relay Takamisawa MAT 4B-212R

    When I check the line out (tape PB) I get clean output from the FM tuner and from an Ipod input with an RCA cable.

    4) Checked fuses for continuity

    Seemed to be fine

    5) Internal Visual inspection.

    There are not any visibly failed capacitors.

    I thought the amplifier board output transistor might be bad - so I unsolderd and tested it with my MM (not sure if I got the right technique) and I believe it has failed.

    It is marked as D357 - 18D and has a T220 form factor and is attached to a board mounted heat sink.

    I found a datasheet from

    http://www.classiccmp.org/rtellason/transdata/2sd356.pdf

    I do not know parameters I have to closely match for the replacement transistor. I need to put this back, so I thought I would replace it with a new one.

    Any suggestions on a replacement transistor would be welcome. None of the transistors I found at mouser were exact matches.

    5) Next steps

    I plan to replace the transistor and the capacitors on the amplifier board

    Do any troubleshooting suggested by others on this board.

    6) Look for a service manual

    Any suggestions would be greatly welcome on the next steps on getting this unit working.
     

    Attached Files:

  2. petehall347

    petehall347 the brandy coffee man

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    Last edited: Mar 29, 2014
  3. bigberts

    bigberts New Member

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    I took the transistor out for testing and removed it from the heat sink before testing. Your website was handy and I found a BD239C om mouser as a replacement.
     
  4. petehall347

    petehall347 the brandy coffee man

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    that transistor looks like its a voltage regulator ..
    do you have the schematic ?
     
  5. bigberts

    bigberts New Member

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    No I do not have a schematic.
     
  6. petehall347

    petehall347 the brandy coffee man

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    what was the diagnosis from testing the transistor ? my guess it must be open at least one way or you could have more problems to fix .
     
  7. elnaldo

    elnaldo Addicted Member

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    As an easy test, check continuity from Emitter to collector, on the output transistors (your 2nd pict)

    If you measure "0 ohm", or continuity, some output transistor is shorted. If you don't have continuity there (your multimeter doesn't "beep"), those transistors are probably fine.
     
  8. Goldinmyear

    Goldinmyear New Member

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    OK...sounds like a fried Resistor, Probley on a cross over (bad connection)
    with in the speaker..Maybe some one tried to up grade it??
     
  9. sregor

    sregor AK Subscriber Subscriber

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    I am pretty certain that is the voltage regulator. As you are getting sound in the pre-out I don't believe that is your problem. First check should have been voltages, which is hard to do without a schematic, but expect about 15 volts on the emitter of the transistor you just tested (2sd357) and if its there, then it probably is okay.
    First step if no relay should be check fuses and supply voltages, then check the output voltage to see if the protection circuit is just doing its job. There are test points on the amp board, near the emitter resistors (white blocks) and you should see low (less the 100 mV) voltages with respect to ground. If one channel has a large DC voltage, then relay will not engage. Besides bad output, common problem is differential pair - probably 2sa798 (usually just marked a798) and is a small flat 5 legged package.
    If the voltages are OK, then need to trouble shoot the protect circuit.
    Be careful measuring voltages - safest method is to use clip leads and connect them before powering up. Another help is to tape up most of your lead so just the last 1/8 inch of your meter lead is exposed. Good luck.
     
  10. sregor

    sregor AK Subscriber Subscriber

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    Vector receivers didn't use the 2sa798 - regular input pairs. The 9000 used an HA12002 protection control IC - I would see if there is one, then check voltages on it.
     

    Attached Files:

    Last edited: Mar 30, 2014
  11. Jeff Levy

    Jeff Levy New Member

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