Bottlehead Forum
Bottlehead Kits => Kaiju Stereo 300B amp => Topic started by: ebag4 on March 06, 2016, 09:46:44 AM
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I started building my Kaiju this weekend. All of my checks have been good, including the glow tests, until I reached the high voltage test, I am not reading any DC. I have been going back through my connections and instructions all morning, I just saw this. Page 38 of the manual tells me to connect the red wire to t9 of PT9 and black to t10, however looking closely at the picture I see that it is wired the opposite. I don't know what impact this has but I am concerned I have been putting voltage through the 220uF and 100uF caps of the wrong polarity. Any recommendation is appreciated. I don't want to put power back on it until I have this issue sorted.
Best,
Ed
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There have been typo's in the manuals before. It happens. But in my experience the photos are always right. I assume this is because the photos are shot from a working unit. But please wait for the official word from Bottlehead HQ before proceeding.
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Yes these wires have been reversed. It is a typo and will be corrected.
This isn't relevant to your problem both for the reason that it would work either way and the fact that this is the heater circuit. It has already been tested (via the 5670 glow test), and confirmed to work. It has no bearing on your high voltage supply and your problem is elsewhere.
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Thanks Josh. I will correct and continue to troubleshoot.
Best,
Ed
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Preamble:
Keep in mind that there is an error somewhere in your high voltage supply. Parts of your amplifier may remain at high voltage, even when unplugged. Proceed with extreme caution.
There was no need to swap the wires. As I stated before, the heaters will work either way. Well they should, but not with the new solder joints apparently (or perhaps swapping strained the wires and one is now broken). Measure resistance between the terminals on the PT and the ones on the socket. This is now a new problem that needs to be solved and is completely unrelated to your high voltage issue.
As for solving the high voltage issue, check the earlier nodes of the power supply to find where it breaks down. Starting closer to the PT, any terminal with a positive capacitor lead should have a positive voltage. Check each node. After unplugging, keep measuring until the voltage has gone down.
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Thanks Josh, I didn't understand that I could have left the wire swapped from your previous post.
Best,
Ed
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Not an open, apparently a short somewhere, I'm blowing fuses. It has to be something after the glow test. I have been back through the build and can't locate any mistakes so it must be a stripped wire somewhere, bummer. I lost a clipped lead off of one of the caps, seems I would be able to see that if it landed in a bad location.
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OK, well a blown fuse could be caused by many things. One thing could be the inrush current from the first time the capacitors are getting charged.
Try a larger fuse (2A is pretty easy to come by, even in a normal hardware store), testing the power supply as instructed. Be ready to pull the plug immediately if you see or smell something funny, but it might be the fuse rather than a wiring error.
If it's still blowing a larger fuse, then there is definitely a wiring error in the HV supply. Post pictures.
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That's apparently what it was, tubes glowing again, thanks. I wish I would have considered that, I'm always leary of using larger than the recommended fuse.
Best,
Ed
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Are the voltages within spec?
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All DC readings within tolerance. The caps charging apparently blew the fuse and had me trouble shooting an issue that wasn't there. Thanks again.
edit, just checked 53u and 65u with the 300b's installed, 74vdc each, looks like we're cooking!
Ed
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Yes, they very first startup with brand new caps can cause more inrush than after they have charged once. I don't think it gets discussed much, but I've seen to many times over the years and twice now in the past week.
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I believe we have a typo on the 2nd instruction on page 64, I beleive it should read D8 not D2. If I'm wrong please let me know.
Best,
Ed
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Man, I am glad you are going through this first. I am following your build closely. It is great that you are so attentive to the details.
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Thanks Drew, I wouldn't follow too closely, I'm trying to do my driver test but i am blowing fuses. Nothing obvious as of yet.
Edit;
Not certain what it was but my A socket appeared that the terminal with the diode and the adjacent terminal may have possibly been touching, when I put it back together my voltages came up and no blown fuses.
Best,
Ed
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I believe we have a typo on the 2nd instruction on page 64, I beleive it should read D8 not D2. If I'm wrong please let me know.
Yes indeed, that looks to be a typo.
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Ed - It looks as though I am having the same issue with fuses blowing at the stage of doing the HV measurements. I bought some wanted 2 amp fuses but all Radio Shack had in stock were 3 amp. I am wondering where you ended up with fuse rating when everything was done?
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Hi drew, sorry to hear that. I am currently running a 3, but I did try a 1.6 after it had played the first night, it blew immediately. I have purchased some 2 amp fast and slow blow but I haven't tried them yet.
All of my measurements were well within tolerance with the exception of the test with 1% tolerance which was 1 volt off. I had seen no issues with it, it is still breaking in but has moments of excellence. I just installed new caps so they will take a bit to break in as well.
If you try the larger fuses just be ready to kill power like Josh mentioned.
Good luck!
Ed
Edit: it took the 2 amp slow blow.
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Thanks Ed - Like I said, glad you went through this first! BTW, those CAPS look great - sorry to hear the Jupiter Copper broke, they get very good reviews. I got Vcaps Cutf for the .1 uf and am thinking Mundorf Silver/Oil for the 10uf. Just can't afford the S/G/O though they get very good reviews.
I'll test with the 3A's. Doc suggested 2A slow blows. I didn't get them because I didn't think I should use slow blow's. I'll know tonight when I get home and try the fuse. I triple checked all the connections, so I am pretty sure it is not a short or a miss wire but you never know. I'll let you know what happens.