Bottlehead Forum
Bottlehead Kits => Stereomour II => Topic started by: Twodawgzz on July 05, 2020, 01:00:59 PM
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I've checked all soldered connections and reheated all of them with a dash of additional solder. Checked all wiring against instructions. Can find nothing obvious causing the problem.
Decided to plug the unit in to see what it does, in spite of no readings. One of the 12AT7s does not light up. All other tubes do.
At this point I am baffled.
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I think it's impossible to have no resistance readings. Double check that you have the red lead plugged into the meter in the Ohms, not the Amps, socket. And make sure you have the meter dial set to ohms (omega symbol).
If that's not the problem, what does the meter show? "OL" (over limit) or "0" (zero)? Try measuring the the resistance between the two ends of a piece of wire. Do you get "0"? If not, replace the battery in the meter.
I would NOT power up the amp, let alone connect it to speakers or headphones, without passing the resistance checks.
cheers, Derek
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Yeah, especially don’t plug the Jagers into this
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First, check the battery on your meter. You might as well replace it with a new one no matter what. Batteries don't cost much. Second make sure that you have turned your meter on. Third follow Derek's advice and make sure that you have set it to measure Ohms. Fourth, set the proper meter range, if your meter is not auto-ranging. Fifth, make sure that the leads are firmly and securely inserted in the correct locations for the measurement that your are about to make. Then try again to get resistance measurements.
It is impossible not to get impedance measurements with a working and correctly configured multimeter.
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One should not plug an amp in that does not pass its resistance checks.
What DC resistance do you get with the meter probes touching?
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I have two multimeters and have had nothing but problems using both of them. One is a Craftsman 82339. The other is a Gardner Bender GDT-331. The Gardner eventually goes to zero when the probes are touching. The Craftsman reads -1 no matter what setting I use. Both have new 9 volt batteries.
When checking resistances with the Gardner, I get all zeroes except when checking numbered connections 29, 32, and 41 where I'm supposed to get a zero reading. For those I get no reading whatsoever.
I've considered getting a Fluke multimeter but have resisted (no pun intended) spending more bucks on another multimeter when I've had nothing but confusion and no success with the ones I have.
What do you experts out there suggest I do?
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Are these older meters? Do the probes unplug from the meter? If so try cleaning the tips at both ends of the probes with contact cleaner and maybe a little steel wool, a scotchbright pad or very fine sand paper. Also if they have a rotary switch that selects the test range try exercising that switch by rotating it thru the entire range a few times. If you do decide to get a new meter it doesn't need to be a Fluke for the purposes of building our kits. An inexpensive meter from Home Depot is usually just fine.
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This meter:
https://www.harborfreight.com/11-function-digital-multimeter-with-audible-continuity-61593.html (https://www.harborfreight.com/11-function-digital-multimeter-with-audible-continuity-61593.html)
and these probes:
https://www.amazon.com/gp/product/B07SD3L9HR/ref=ppx_yo_dt_b_asin_title_o00_s02?ie=UTF8&psc=1 (https://www.amazon.com/gp/product/B07SD3L9HR/ref=ppx_yo_dt_b_asin_title_o00_s02?ie=UTF8&psc=1)
With your current meters, can you measure the DC voltage of a 9V battery?
How about the DC resistance of a woofer?
The Craftsman should work just fine for your resistance readings, but you'll need to be on the correct range.
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Weird to have two meters with fresh batteries not working. I'd check the fuses in the meters.
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Thank you for all the quick responses. I'm on hold for a day or two until I have a definitely working multimeter.
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Okay. Got a multimeter working properly.
All resistance readings are good except terminals 29, 32, and 41. They should be 0, but I get no reading at all on those. I checked the capacitors soldered to those terminals. They are all correct as far as striped and non-striped leads per instructions.
Any ideas?
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What do you mean you get no reading on those?
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What do you mean you get no reading on those?
The reading is 1 like it is when disconnnected from all terminals.
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All resistance readings are good except terminals 29, 32, and 41. They should be 0, but I get no reading at all on those.
Any ideas?
Those are all wired together with black wires to the rest of the ground terminals in the amp. Either you are missing a black wire, or one is loose and not making a good connection. You could post photos of your build to be sure you have all the black wires there.
Whatever you do, do not power up the amp like this.
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Those are all wired together with black wires to the rest of the ground terminals in the amp. Either you are missing a black wire, or one is loose and not making a good connection.
Exactly right, Paul. Thank you! Ground wire to terminal 29L, which was very hard to see, had come loose. Resoldered it, all resistance and voltage readings were fine, and the amp now plays beautifully. Now on to the three upgrades after breakin.