You've seen this before: Amp does zilch; next move...?

Discussion in 'Amp Central Station' started by RoscoeElegante, Sep 22, 2020.

  1. RoscoeElegante

    RoscoeElegante Friend of Leo's

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    Okay, if this seems familiar, it's 'cause I JUST got my '73 Bandmaster Reverb back from the shop. In July (I think), I had asked the forum about why it went ga-ZAP, complete with smoke and screaming electrons sounds, back in the summer after exactly 60 min. playing time, after the first repair guy did apparently not enough to it.

    And I just posted this yesterday, about the second round of repairs, with a different, seemingly very professional repair guy:
    https://www.tdpri.com/threads/is-a-7522-12at7-anything-odd-3-other-73-bmr-questions.1049645/

    Didn't have a chance to turn it on until today.

    And NADA.

    Very slight background hum/it's-working sound with it on standby. That sound gone, and NO sound forthcoming, when standby flipped off.

    Checked cable and guitar through two other amps. All okay.

    Check the BMR's speaker cab through another amp head. Just fine.

    Even checked if somehow the standby on/off got reversed but no sound when it's on standby, either.

    So yes, back to the shop it will go! Will have to wait until next week due to work, but damn, this is frustrating.

    I drove it home carefully. It was sitting on the passenger seat, all but buckled in. Had my hand on it the whole way, in fact.

    Pilot light comes on and stays on, nice and steady.
    Tubes light up.
    A very slight electronics/ozone/warming tube smell.
    Checked all the guitar inputs, all the knobs.
    Made sure I was in the right speaker input. Repeatedly.
    Triple-checked speakers, cable, guitar.

    But NADA on any sound!

    Any take on this? What the hell could've happened between the shop and being walked 100 yards to the car, riding home stably, being baby-carried into the house, and set carefully atop the speaker cabinet?
     
    Last edited: Sep 22, 2020
  2. D'tar

    D'tar Friend of Leo's

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    3X=GTFO

    New tech time. ImHO!
     
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  3. Collin D Plonker

    Collin D Plonker Tele-Afflicted

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    Sorry to hear about this. It must be frustrating.
     
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  4. Wallaby

    Wallaby Tele-Afflicted Silver Supporter

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    I recently had a mildly embarrassing post here about my amp not turning on... and it was the pilot lamp.

    You probably already covered that, but I thought I'd mention it.
     
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  5. RoscoeElegante

    RoscoeElegante Friend of Leo's

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    This second dood is a different one from the first. First guy was a electrical engineer and a hobbyist when it came to amps--who, in all fairness, was going through a family problem. So kinda my bad on that one, in that I thought a standard check up would be okay, and shoulda just taken it elsewhere he got beset.

    This current guy is a shop's expert. Comes highly recommended and seems to really know what he was doing. I don't want to assume he made a mistake, as they stand behind their work real well, he's done fine work (on guitars) for me before, etc. But it sure is...puzzling!

    And frustrating! I actually got a ton of work done last night and earlier today to clear my decks for this. Now my students might expect me to be getting work on schedule ALL the time. That's a dangerous precedent to pay when amp won't play!
     
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  6. Boreas

    Boreas Tele-Afflicted Silver Supporter

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    Did Tech #2 replace any components? It wouldn't be the first time a new electrical component failed out of the gate. Or a cold solder joint. I am sure he will take care of it for you promptly. Crappy luck though...
     
  7. RoscoeElegante

    RoscoeElegante Friend of Leo's

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    Thanks, Wallaby. I've now reworded my original post where I had mistakenly referred to the pilot light as the "jewel."

    Just bizarre. Maybe the output transformer is open? The 2x12 cab is working fine, and the BMR took that cab's jack just fine before, so it's nothing outside the BMR itself.

    I need to go lift weights and curse gravity or I'll grade my students' exams too harshly! Damn electronics, making me exercise!
     
  8. RoscoeElegante

    RoscoeElegante Friend of Leo's

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    Hi, Boreas. Yes, he did. I listed those in the thread I linked above:

    "He did a thorough job. Changed all the filter caps, the coupling caps, and a broken plate resistor. "Upgraded voltage ratings to 500," cleaned the footswitch, tested everything carefully, brought it up slowly, etc."​

    Amazing how much we value this stuff. I had a mechanic who didn't put a tire on right after a brake job. The tire snapped off the bolts and rolled away and I scrape-skidded to a stop. That didn't bother me as much as the BMR not working.
     
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  9. schmee

    schmee Doctor of Teleocity Silver Supporter

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    I'd be checking the input jack.. try another input.
    The speaker jack.. isn't rotated or something and grounding?
    The standby switch?
    The volume knob is on correct rotation right? So you dont think it's on 5, but on 0?
     
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  10. kennl

    kennl Tele-Afflicted

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    What the hell could've happened between the shop and being walked 100 yards to the car, riding home stably, being baby-carried into the house, and carefully set atop the speaker cabinet?

    standby switch broken (open) ?
     
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  11. RoscoeElegante

    RoscoeElegante Friend of Leo's

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    Thanks, schmee.

    I tried all the inputs, several times. With three different cables, all of which I checked on other amps.

    The speaker jack seems fine. I put the plug in and out, carefully and fully, it seated fine, seems straight, etc.

    It was weird, at least to ignorant me, that the noisefloor was audible when standby switch was on Standby, but not when it was switched off/to pass sound. That canceled even the noisefloor. Absolutely no sound audible when the standby switch was off.

    Checked the volume knobs on both channels several times. Checked all knobs. Even did the footswitches on and off in different combinations. Nada!
     
  12. RoscoeElegante

    RoscoeElegante Friend of Leo's

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    As per my reply to schmee above, this seems a possibility to me. Then again, there are others--cold solder, output transformer open, new component breaking, etc. The tech brought it up slowly and checked everything extensively, he said. He really "enjoyed" working on "this great piece of Americana," and is highly recommended. So...who knows!
     
  13. Boreas

    Boreas Tele-Afflicted Silver Supporter

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    Footswitch hooked up to the correct jack? Still spitballin'...
     
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  14. RoscoeElegante

    RoscoeElegante Friend of Leo's

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    Yep! Reverb cables in there correctly, too. The tech even polished up the tolex and handle!
     
  15. schmee

    schmee Doctor of Teleocity Silver Supporter

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    I did have the standby switch fail on my BFDR, just wouldn't come on, but popped when switched.
     
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  16. D'tar

    D'tar Friend of Leo's

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    I may have been too harsh. It sounds as though he did a decent tune up there. This could be simple as a bad tube. Ive rolled tubes to find a "sound" and have things returned as the "right" tube went microphonic and crazy as a trainwreck lol. Once things are straight, I would expect many trouble free years of service.
     
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  17. RoscoeElegante

    RoscoeElegante Friend of Leo's

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    Thanks, gents. Good deductions and suggestions from much wiser people than myself. I'm very late to the circuitry game, and quite the layman about it all despite my fascination with it. I'll just leave it alone and take it back to the shop Monday of next week when I'll have some time to do so. Otherwise it will drive me crazier than usual.

    "Serenity now, serenity now......"
     
  18. nathan5782

    nathan5782 Tele-Meister Silver Supporter

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    Even though the tubes heaters are lit up try removing and reseating the tubes. No audible pop/thud when switching the standby? Weird
     
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  19. RoscoeElegante

    RoscoeElegante Friend of Leo's

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    Thanks for your suggestion, nathan5782.

    I just reseated the tubes and tried the amp again. Still the same result: the big NADA. No pop, thud, click or anything when switching the standby, other than that the noisefloor completely stops....
     
  20. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

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    I had a '67 bassman cross the bench. The owner had just purchased it in non-working condition. Everything seemed fine after a cap job and general clean up. I was about to call the owner to tell him I was finished with the repair. I was doing a last check of voltages when it started oscillating. It was an intermittent problem. Not easy to track down when it acts fine most of the time. I found/replaced a cracked resistor. I thought that solved the problem. Again I am about to call the owner when it happened again. Found/replaced another resistor. I had told the owner of the intermittent problem and when I gave the amp back, I told him the symptoms to watch for. He hasn't called back so I assume the amp is fine.

    Bottom line... not every problem is easy to diagnose. Some are head scratchers. Take it back to the tech and let him try to find the underlying problem. I doubt it left his shop in a non-functioning state even though it did not work when you tried it. You said he is a "seemingly very professional repair guy", give him a chance to make it work. (Amps can be frustrating for repair guys to work on too.)
     
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