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Thread: Hot Rod Deluxe problem

  1. #1
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    Hot Rod Deluxe problem

    Hi Guys, a friend of mine had a HRD III that makes horrible noise when you select "Bright" on the Normal channel. it sounds like a shorted input jack. the wierd part is the Drive and More Drive work with no problem.... even if Bright is selected. the Normal channel works fine as long as it is not on Bright.

    Anybody ever run into this? there is only one real amp tech in town & he is semi-retired & busy, etc. I figured its worth a shot to see if any of you have ever seen this before. thanks

  2. #2
    Forum Member mickeydg5's Avatar
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    Re: Hot Rod Deluxe problem

    Hello
    It seems no one tried to answer. For starters the Normal/Bright switch only affects the Normal channel, not the drive channels. When you switch to Bright components in the cathode circuit of V2-A are activated. The proper outcome depends on grounding which is switched via relay K1-B. If for some reason that relay, connections, traces or wiring are having issues it could inject noise into the cathode circuit of V2-A. All other channel manipulations would still operate correctly as you described.

    That is what I see on the schematic and is the place to look. I hope that helps.

  3. #3
    TFF Stage Crew
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    Re: Hot Rod Deluxe problem

    I don't know about this particular model, but my old Blues Jr (from the same series) had a similar problem, & only at certain times. It seems the tube sockets had broken loose from the PCB. I'm pretty sure I discovered the breaks while trying to re-tension the connections inside the tube sockets. You'd be surprised how much difference this will make in an amp! They still made enough contact to keep the amp running, but at certain peaks in volume it would rattle the sockets & produce that crackling, shorting-out sound. A little solder & flux, & heating of the joints to re-flow the solder was all it took.
    I'll tell you a little secret but I cannot advise this action, lol:
    To pinpoint the problem, I removed the chassis from the cabinet but kept everything connected. I turned off all the lights in the room, plugged in a guitar, powered it up & played for awhile to see if I could produce the symptoms. In the dark I could see tiny blue arcs in & around the tube sockets that coincided w/the sound. That's how I found it.

  4. #4
    Forum Member FrankJohnson's Avatar
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    Re: Hot Rod Deluxe problem

    Cogs -

    I could see the solder move when I wiggled the tube in mine.
    Re-tinned - seemed to fix it.

    I also had tubes go bad, had resistors go and ......I can't recall.....something else - maybe a cap?

    It plays pretty well now, and actually sounds good.
    Kenny Belmont
    >:^{I)>

  5. #5
    Forum Member NTBluesGuitar's Avatar
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    Re: Hot Rod Deluxe problem

    Sometimes the squealing happens because of the dreaded power resistors R57 & R58...those set the voltage for the opamp-driven parts of the amp - with the bright engaged, it could be introducing some oscillation at higher frequencies due to the 'hotter' power.
    "...pray do not imagine that those who make the noise are the only inhabitants of the field;
    that, of course, they are many in number; or that, after all, they are other than the little,
    shriveled, meagre, hopping, though loud and troublesome, insects of the hour."

    -Edmund Burke

  6. #6
    Forum Member mickeydg5's Avatar
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    Re: Hot Rod Deluxe problem

    R57 and R58 are plate resistors for the PI in a Hot Rod Deluxe III.

  7. #7
    Forum Member FrankJohnson's Avatar
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    Re: Hot Rod Deluxe problem

    when mine crapped in 2005 - the issue (I quote from a post then....)

    Resistors R61 and 62 (High voltage output section) needed replaced. C36 Capacitor needed resoldered and he glued it down, saying the weight of it may have contributed to its becoming detached/weakened. The 2 6L6C Tubes needed replaced.

    that was from the tech - I don't think the tubes needed replaced now looking back......but.....

    I had it back in the shop at least twice more, and again resistors - but I can't recall which ones.

    I still have it - but would probably let it go for a nice delta blues or ac15 - maybe even a blues junior.
    Kenny Belmont
    >:^{I)>

  8. #8
    Forum Member NTBluesGuitar's Avatar
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    Re: Hot Rod Deluxe problem

    Quote Originally Posted by mickeydg5 View Post
    R57 and R58 are plate resistors for the PI in a Hot Rod Deluxe III.
    DOH! I was referring to R78 & 79
    "...pray do not imagine that those who make the noise are the only inhabitants of the field;
    that, of course, they are many in number; or that, after all, they are other than the little,
    shriveled, meagre, hopping, though loud and troublesome, insects of the hour."

    -Edmund Burke

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