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Heathkit SB-610 Monitor Scope - Need Help

Discussion in '"Boat Anchor" & Classic Equipment' started by WJ5G, Oct 13, 2021.

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  1. WJ5G

    WJ5G Ham Member QRZ Page

    Does anyone know or have a way to tell me what fuse is used in the scope. I know it is .r watt but it appears to be a slow blow or something of that nature.

    Also, the Horizontal gain controller is locked and it has no markings on it to tell me what to exchange it out with.

    If someone could help me with either or both of those questions I will truly appreciate it.

    Callen WJ5G
  2. W9GB

    W9GB Ham Member QRZ Page

    Heathkit SB-610 Monitor Scope Assembly Manual and Schematic.

    Horizontal Amplifier : 1/3 of 6C10 vacuum tube
    Horizontal Gain Control (R306, Potentiometer) : 1 Mohm, likely linear, 24mm diameter
    Guitar Amp restorers frequently use a control of that Ohm range.

    421-20 : 1/2 Amp fuse (Shown on Schematic, 3AG, 250V, Slow-Blow)
    Heathkit of the Month #60
    by Bob Eckweiler, AF6C
    October 2014
    Heathkit SB-610 Station Monitor Scope
    Last edited: Oct 13, 2021
  3. WB9TEN

    WB9TEN Ham Member QRZ Page

    The fuse is a 1/2 amp slo-blow. I would be checking power supply issues as this is not a fuse that goes open under normal conditions. Hayseed Hamfest sells a nice kit that includes an exact replacement for the "can" capacitor.

    The Horizontal gain is a 1 Meg and probably a linear. I would try a little TriFlow on the shaft and maybe heat it with a soldering iron before I would give up on it. Not uncommon for those Heath pots to sieze there.

    If you need a complet manual, send me an email.

  4. WJ5G

    WJ5G Ham Member QRZ Page

    Thank you both.
  5. WJ5G

    WJ5G Ham Member QRZ Page

    Thank you both for your reply.
  6. K8CCA

    K8CCA Ham Member QRZ Page

    I restored one of these a year or 2 ago. Most of the resistors had drifted way high. I also replaced all the caps as well. I also reflowed all the solder joints as mine had poor soldering completed by the builder. I ordered all the caps from and was able to get all the values and voltage rating met or exceeded. I seem to rememeber there where some pretty high voltage caps in there. Good luck with you project!
  7. W9GB

    W9GB Ham Member QRZ Page

    IF you need a NEW CRT, some of the Last ones produced in East Asia,
    are being sold on eBay and by Sphere (Canada).
    Earlier QRZ Tech Forum threads covered Quality & Reliability of specific reseller.
    Yes, the SB-610 has 1,000 V and 1600 V capacitors for the CRT section.
    Cornell Dubliner Electronics (CDE) Type 940C Axial capacitor series is a Good Replacement
    CDE Replacement Capacitors readily available from Digi-Key and Mouser.

    QRZ Tech Forum (2013):

    Hayseed Hamfest sells a complete Heathkit SB-610 Re-Cap Kit
    Refurbishing the Heathkit SB-610 and “The Collins 610C-2 Makeover”
    by Stu Martin, K2QDE
    Rev: May 2007
    Collins Radio Association
    April 4, 2012
    Last edited: Oct 14, 2021
  8. W9GB

    W9GB Ham Member QRZ Page

  9. WA1GXC

    WA1GXC Ham Member QRZ Page

    Surplus Sales of Nebraska
    New-in-box RCA-manufacture 3RP1

    Q: "Why has my CRT raster burned a pink hole on the faceplate?"
    Ans.: Because you bought it on E-Fraud

    Last edited: Oct 25, 2021

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