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Airline GIM-9131A knowledge/repair question

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  • So, not being a musician, when an amp that has multiple inputs is used, do people actually use multiple instruments through one amp at one time?

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    • Don't think in terms of inputs, think in terms of independent channels. In your amp, I'd gladly plug two guitars into it, because each channel has its own preamp. Just use one instrument per channel. This works with most vintage style amps; they were almost intended to be self-contained PAs. Tweed Fenders would have a Mic channel as well; some Ampegs had one also. Voxes & Marshalls, the old ones...

      It's not the same as a modern "channel-switching" amp, or a single-channel amp with a high & low input. I play both guitar & bass through my Bassman head all the time.

      Justin
      "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
      "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
      "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

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      • With my DVM set to the 10 amp scale, I measure the amp draw on startup at about .25 amps. Zero amps while playing regardless of the volume. But it bounces around pretty good when I turn it off. I have seen 8 amps on shutdown. All these measurements were taken while NOT in standby mode.

        Putting it in standby mode and then using on and off I measure very minimal draw and also minimal draw when I go out of standby mode.

        I would see like a 2.25 amp breaker is more than sufficient and it actually seems safer to me since I can see that under normal circumstances there is very little draw.

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        • I was wrong about standby mode. I see similar results whether in standby or not.

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          • Check the circuit breaker that you want to use and see if it has a voltage rating printed on it. If it is from a speaker, it may not be rated for 120 vac.

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            • There is no voltage rating on the breaker. No part number either.

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              • I hooked up the breaker from the speaker. The amp seems to work fine. Again, with my limited electronics knowledge, if the breaker wasn't rated for 120 volts, would it still work or would it have smoked right away?

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                • Been playing a CD over 6 hours straight now at various volume levels. I think I can call it good, right?

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                  • The big surge will be when the heaters start up from cold. I don't think your meter is catching that surge as you said the meter did not show it. So that is what you want to test. Maybe every 5th time it's started from cold, the breaker will pop. Just a guess, but that is what you need to find out.
                    And as 52Bill noted, the breaker may not be rated for line voltage, so there is a safety and liability issue you have to decide on.
                    The voltage rating is not something that determines whether it will work or not, it is about whether it can safely withstand operating under that voltage.
                    Originally posted by Enzo
                    I have a sign in my shop that says, "Never think up reasons not to check something."


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                    • Thanks. I am going to just order one up to be sure and put it back to original specifications.

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                      • New breaker is in and everything seems to be working fine. I have two annoying things left. I think the panel switch light might be bad. When the panel switch is off, the lights are in "dim" mode. The middle light is fairly bring and the two outside lights are dim. i think that is correct. When you hit the switch the middle light gets a little brighter but the two outside lights go off completely. It seems like they come on every now and then though. Maybe once out of 50 times you hit the switch. I have cleaned up the switch the best I could.

                        The other annoying, but maybe perfectly normal, is the reverb dial. With nothing jacked in and the volume off, if I turn up the reverb I hear a very faint buzz that gets a little louder as the reverb is turned up. It isn't loud, it is more of an annoying sound because it it is noticeable. Knowing nothing about amps and how they are supposed to work, it may be normal, or not. I am not going to dig into it, just curious of how it should be.

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                        • In re-reading some of the posts I see again that g1 posted in #106:
                          Also note that the reverb tank will pick up noise at higher reverb settings

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                          • I think I got this about as far as I can go with it. I want to say thank you to everyone that chimed in to give me a hand. You were more than generous with your time and advice.

                            Thank You.

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                            • It is so much harder to fix something by remote control. A reverb problem of any sort should not be beyond a competent tech. You might consider taking the amp to someone. Hey, I think I can fix anything, but when my computer breaks I take it to someone else.
                              Education is what you're left with after you have forgotten what you have learned.

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                              • As you suspect, it does sound like the dim/bright switch is bad.
                                Originally posted by Enzo
                                I have a sign in my shop that says, "Never think up reasons not to check something."


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