Bottlehead Forum
Bottlehead Kits => Stereomour II => Topic started by: thoven0215 on April 28, 2022, 06:20:00 PM
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When doing the resistance checks I noticed that all the checks on the left side of the board went ok, but almost everything on the right side measured as infinity. 15, 16, 17, 18, 36, 37, 39, 40 all measured as infinity. I reflowed the solder joints to no avail. What should be my next steps? Thanks
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Here are some pictures.
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When the manual says "attach", that means you need to physically attach a wire or component lead to a terminal strip. Your build is very unlikely work if all those connections just pass through a terminal strip or tube socket and don't bend up at least, if not up and around the terminal. You need to go through your build and do that to every single connection before thinking about turning it on.
Terminal 5 wires to terminal 8. Terminal 8 wires to terminal 13. Terminal 13 wires to terminal 16. These wires all appear to be there but if there are soldering issues that could be discovered in the resistance checks.
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https://forum.bottlehead.com/index.php?topic=13797.0 (https://forum.bottlehead.com/index.php?topic=13797.0)
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I attached them and soldered again, but I still get infinity for the same terminals.
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They are wired together. Wires are 0 ohms. If they are wired together, you'll get zeroes where you're supposed to. If you have flaky/broken connections, you won't get your zeroes.
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I'm not exactly sure what you mean. I get all the 0s where I am supposed to, it is just that I get infinity for a lot of places that shouldn't measure at infinity.
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16 and 18 are supposed to be zero and you listed them as infinity.
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I am very confused on how this happened but after measuring again everything just resolved itself. Thank you for your help Mr. Birkeland.
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My fuse ended up blowing. Do you have a recommended replacement, or can I just buy any 1.5 A fuse off the internet? Is there a specific area I should be looking to correct the fuse blowing? Thanks.
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Your power supply diodes are installed backwards.
Any old 20mm 1.5A fuse should do the job.
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Good catch P.B.
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I replaced the fuse and went onto testing voltages, but when I got to terminal 27, there was a big pop noise and something bright. I disconnected the power. I noticed the tubes still glowed, but the measurement on everything went to 0 volts. The fuse is also still ok. What happened?
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You have 0V at terminal 44?
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I have 423 Volts at terminal 44.
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I also notice that the left side of the leds on the pcb did not light up if that helps at all.
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OK, so the measurements on everything didn't go to 0V ;)
You'll need to do a whole voltage check and just let us know which terminals are 0V.
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Terminals 1, 2, 6, 7, 21, 22, 24, 25, 27 all shouldn't measure at 0 but measure at 0. I also measured 41-45 and 41 comes at 0 as well.
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Does 34 provide a proper measurement? How about 30?
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30 measures at 425, which is about 7% more than the 398 listed. I just attempted to measure 34, and the same pop happened. I just turned off the amp.
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I would look for loose components around 34. In the original photos you posted, 35L doesn't look to be well soldered, and those wires moving around could make a pop.
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I soldered them again, and now I think the pop has taken out the right side too. 19 and 20 measure at 3 volts. 31 measures at 450. 34 measures at 3 volts. 36, 37, 39, 40 all measure at fractions of a volt. 41 measures at 0. 42 measures at 225. 43 measures at 0. 44 measures at 450. 45 measures at 223. Everything else measures at 0.
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Loose and/or damaged 130 ohm resistors and/or loose black wires leaving the 41-45 terminal strip will do this. Did you go through the amp and wrap all the connections and resolder them?
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I did, and how can I tell if the resistors are damaged? The resistors are not loose, and I just reflowed the terminals 41-45 again just to make sure nothing is out of order.
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I did, and how can I tell if the resistors are damaged? The resistors are not loose, and I just reflowed the terminals 41-45 again just to make sure nothing is out of order.
You have the correct voltages on 41-45, so I would suggest leaving those alone for now. A damaged resistor will measure OL with the amp off and discharged if you try to use your meter to measure it.
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I attempted measuring them, and both of the 130 ohm resistors measure at infinity.
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You can unsolder one end of each and double check them with one end poking up and not connected to anything. Most meters will measure these in circuit, but some will not.
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I disconnected them and measured again, but their value just keeps going up until my multimeter can't measure them anymore.
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OK, they are probably blown and need to be replaced.
When you get them replaced, you can tape over the metal tip of your red meter probe so only the metal point sticks out, and that should help avoid potentially shorting a terminal with 400V on it to a terminal with 0V on it next door.
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Just out of curiostiy, is it possible that it could have also been a power transformer issue? Further, I was using alligator clips to measure, and I thought I made sure to not touch other terminals. Could there be an alternate reason for them shorting when I test the terminal? Also where would you recommend me buy resistors? Nevertheless, thank you very much for your help Mr. Birkeland. I will update once I get the resistors.
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Just out of curiostiy, is it possible that it could have also been a power transformer issue?
No.
Could there be an alternate reason for them shorting when I test the terminal? Also where would you recommend me buy resistors?
Loose parts will move around when you probe a terminal, and that can cause sparks if they are not well connected. You can e-mail replacementparts(at)bottlehead(dot)com regarding obtaining some new 130 ohm resistors.
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I just soldered in the new resistors. Just wanted to check with someone and make sure that nothing looks off.
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I don't see anything off, but do be sure that all the striped capacitor ends land on a terminal strip with black wires connecting to it (with the exception of one of the 220uF/250V caps, which will have its striped lead landing where a white wire connects).
If the amp powers up and the fuse doesn't blow, just check the DC voltage at pin 2 on each of the 4 pin sockets. That tells you what you need to know with a lot less fuss.