Here's why factory service manuals are useless.

Discussion in 'CB Radio Forum' started by rabbiporkchop, Dec 26, 2020.

  1. rabbiporkchop

    rabbiporkchop Road Train Member

    9,267
    6,054
    Feb 9, 2012
    Wapwallopen, Pa
    0
    Without a matched set of finals the service manual is useless. Any tech who says otherwise is clueless.
     
  2. Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.

  3. Timin770

    Timin770 Road Train Member

    1,302
    1,094
    May 27, 2011
    Canton, GA
    0
    Yes I saw matched vs unmatched. The important part would be to see numbers on the finished product
     
  4. rabbiporkchop

    rabbiporkchop Road Train Member

    9,267
    6,054
    Feb 9, 2012
    Wapwallopen, Pa
    0
    The important part is measuring spurious emissions after all is done.
    Impossible to eliminate them with the factory finals.
     
  5. Timin770

    Timin770 Road Train Member

    1,302
    1,094
    May 27, 2011
    Canton, GA
    0
    Ok. Let's see
     
  6. Night Stalker10

    Night Stalker10 Road Train Member

    1,085
    534
    Jun 26, 2017
    0
    Of course he's going to see certain numbers with the test jig he built. The problem is, that the numbers are going to change when installed in the radio, due to impedance of the different circuits. At least that's the way I understand it. Again, I think it's a lot of unnecessary time and money spent just to talk on the CB band. I really don't think anyone will notice a small amount of spurious emissions that a radio will put out. Even just by using a service manual alignment.
     
    Timin770 Thanks this.
  7. Ridgeline

    Ridgeline Road Train Member

    17,944
    76,346
    Dec 18, 2011
    Michigan
    0
    I’m trying to figure out what does this have to do with the factory service manual?
     
  8. rabbiporkchop

    rabbiporkchop Road Train Member

    9,267
    6,054
    Feb 9, 2012
    Wapwallopen, Pa
    0
    Google DTB 98VHP.
    Dave is a good tech.
    Without matched final transistors in parallel, the greatest tech in the country is wasting his time trying to do a factory service by following the service manual.
    It will still be a splatterbox, and you won't like how it sounds.
    ( remember the AT-6666 you tossed )
     
  9. Night Stalker10

    Night Stalker10 Road Train Member

    1,085
    534
    Jun 26, 2017
    0
    Well I don't think you can call that a factory tune on that radio. At least not a very good one. The finals and drivers were set too high, as was mentioned in the video. They were around 4.3 to 4.6 vdc, when the driver should be 3.75vdc and the finals 3.5vdc, as per the manual. Who knows what person may have been in that radio since DTB worked on it. The radio looks like it's had a hard life.
     
  10. Ridgeline

    Ridgeline Road Train Member

    17,944
    76,346
    Dec 18, 2011
    Michigan
    0
    ok I guess you don’t understand the question, the factory manual has nothing to do with the replacement of the finals, the alignment instructions seem to miss something that is common knowledge in multiple device amplifiers. As night mentioned, overdriving the devices produce the problems, you can get by with mismatched devices as long as the drive current and voltage isn’t slamming them.

    I didn’t say I didn’t like the way the radio talked, it was receive that was a problem for me.
     
  11. rabbiporkchop

    rabbiporkchop Road Train Member

    9,267
    6,054
    Feb 9, 2012
    Wapwallopen, Pa
    0
    That's true but the service manual makes an assumption there's no quality control problems which is an awful big assumption. The alignment procedure can't even begin until unity is achieved in the RF section. This is the biggest mistake everyone makes.
    Everything needs to be done in chronological order otherwise you're not gonna be happy with the results if a crucial step is skipped.
     
  • Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.

  • Draft saved Draft deleted