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Have the word SHOULD be striken from the vocabulary

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  • Have the word SHOULD be striken from the vocabulary

    I"m wondering how many times I need to take this Fender Hot Rod Deluxe III apart to address the Relay K1 to make the Normal channel work. I suppose one could permanently attach a human hand pushing it towards the side of the cabinet, as that appears to be what is required. I guess the next step is again to take the PCB back off the mounts, unsolder the relay and mess with it unmounted on the board. I'm not yet convinced the relay is just BAD. It SHOULD work. The voltages at TP31 are correct. Reading 1.30V in Normal, 1.00V in Drive and More Drive. It just works when it wants to. Or, if you push on the relay. Relay has been re-soldered twice. So, obviously there's more PCB wiring from the TP and U3 Pin 5 and Q3 than is shown. Just needs a human finger to make it work. I do dearly love Fender PCB's sometimes. Maybe just a bad relay?

    Pulling the bloody thing apart again, and this time removing the relay. I suppose I could swap the two relays....maybe the problem will move?
    Logic is an organized way of going wrong with confidence

  • #2
    Having removed both K1 and K2 from the PCB, I found to my delight Relay K1 is NOT a DPDT. It's a '1.5-pole/Double Throw. On one side, obviously the side that is supposed to let signal flow thru the contacts and allow the Normal Channel function to happen....doesn't happen. Now I've HEARD it work. It's happened at random, and has been able to work by physically pushing on the relay, but now, out of the PCB, I cannot get the Normally closed side where the problem is to close. I get the other three modes to work on the two poles....just not this last one. SHOULD WORK. Sigh....24VDC coil. Very Common foot print, so should be easy to find. Just now have to order and wait for it. I can't think of anyplace here that I have one. RATS.
    Logic is an organized way of going wrong with confidence

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    • #3
      Sounds to me like the relay is hanging up intermittently. Pushing on it probably is releasing whatever is holding it. I would have replaced that puppy straight away.
      It's weird, because it WAS working fine.....

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      • #4
        Originally posted by Randall View Post
        Sounds to me like the relay is hanging up intermittently. Pushing on it probably is releasing whatever is holding it. I would have replaced that puppy straight away.
        That's what I'm now doing. Only I don't have any on hand, and just got thru ordering 4 pcs, so I WILL have some on hand for the next one of these Hot Rod series amps defies the word SHOULD. I wasn't able to over-voltage the one N.C. contact connected via clip leads to my power supply to see what's happening with the silly thing. NOT sure WHAT is happening when it's soldered in and pushing on it got the signal to pass...or it just decides to work on its. MAYBE logic. Great state!
        Logic is an organized way of going wrong with confidence

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        • #5
          There's probably a mil spec version of that relay. Often rated at 28v but spec'd to work lower. If it was my amp i'd be looking to replace it with one, but a customers i would use the factory equivalent part.

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