Heath Sb-614 Rebuild Question ???

Discussion in '"Boat Anchor" & Classic Equipment' started by K5FRH, May 3, 2021.

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  1. K5FRH

    K5FRH Ham Member QRZ Page

    I am putting together the parts list to rebuild/update a Heath SB 614 Station Monitor. Currently the unit works fine with the exception that the display is "pinched"...ie the max size is about 1 line either side of the center line....using 100 watts RF SSB signal.

    Obviously something is reducing the signal strength in the vertical circuit.

    I decided as a first step to replace ALL of the electrolytics in the unit. If you have experience rebuilding these units, what else would you recommend I replace ?

    Thanks, Rod, K5FRH
     
  2. WB8NQW

    WB8NQW Ham Member QRZ Page

    Is there a switch to adjust sensitivity for the transmit power used?
     
  3. K5FRH

    K5FRH Ham Member QRZ Page

    Thanks for the suggestion and I have looked at that. I have decided to go ahead and replace all of the electrolytics....there are not that many, but I want to rule them out...especially the three .1 in the HV supply.

    Thanks again, ROd
     
  4. K8CCA

    K8CCA Ham Member QRZ Page

    I have a Heathkit Station monitor that I replaced the caps in it and still had issues with the entire screen being filled and the focus. A bunch of the resistors had drifted very high. I went thru them all and replaced them and it's working great now. I would recommend checking the resistors when your in there. Have fun!
     
  5. K5FRH

    K5FRH Ham Member QRZ Page

     
  6. K5FRH

    K5FRH Ham Member QRZ Page

    Thanks...that was going to be step 2. Rod
     
  7. W9WQA

    W9WQA Ham Member QRZ Page

    shotgunning parts is a waste of money and time.
    i dont service a lot of stuff but i have as much or more elex stuff in use as anybody.

    i fired up a 75 yr old recorder,worked , no caps changed.;

    in 1959 i built a copy of a juke box amp with junk parts. yrs later my dad changed a filter in it.
    in ?1972 i changed a cap in the vert circuit in a 7 yr old tv.
    i built dozens of kits and 3 home brew amps..
    still waiting on cap 3...
    you shotgunners keep the parts guys rich...
    if you follow any sensible procedure, changing parts is the LAST STEP...
    i posted one last week..
     
  8. W3SLK

    W3SLK Ham Member QRZ Page

    W9WQA said:
    There is a lot to be said in those statements. Exchanging one problem for an 'owner induced' problem leads to headaches and frustration. However, I have been the recipient of equipment failure occurring when I need it most, knowing I should have changed something. That is just as frustrating. 'Ya spin the wheel, ya take your chances!'
     
  9. WB9TEN

    WB9TEN Ham Member QRZ Page

    Rod,

    You are on the right track looking in the vertical circuit. The HV would typically cause a problem with intensity.

    That said, in my experience with Heathkit units of that era, I have found plenty of electrolytics that were leaking. The brown paper covered 'lytics just get replaced without a second thought. And as K8CCA mentioned, resistors can drift and Heathkit 1/2 watt resistors are notorious for drifting. Also, don't overlook the possibility of a dirty contact in the vertical chain.

    Unfortunately, the Heath voltage charts rarely show ac or dynamic conditions. I would work slowly from input to the CRT. Check the circuit around one stage and then see if it made a change before you move on. Working with boat anchors can be a tedious process.

    Just wanted to confirm what has already been said.

    Good luck,
    Dave
    WB9TEN
     
  10. KI4ZNV

    KI4ZNV Ham Member QRZ Page

    Replace electrolytics. TEST resistors in circuit... if they measure much higher than the stripes would indicate, replace them.
    But don't even test electrolytics, just replace them.
     
    KS4W, KM1H, N2EY and 2 others like this.

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