Bottlehead Forum
Bottlehead Kits => Kaiju Stereo 300B amp => Topic started by: ArtnShit on February 23, 2022, 06:19:26 AM
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Hi,
Total noob question- Trying to adjust the humpots, but I am getting nothing on my meter. My meter is only capable of reading the lowest scale of AC as 200V, not 200m, is it just not sensitive enough?
Thanks!
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Could be that's the issue. Try connecting the amp to speakers and putting your ear right up against one speaker. Trim the hum pot on that channel for lowest noise, then repeat on the other channel.
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I hear only a little hiss from the tweeter in either speaker, nothing my SS amp did not have.
I am only getting sound out of the left channel now, though. Any advice on how to troubleshoot?
Using V1 Klipsch Cornwalls if that changes anything.
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How were your voltage checks? Are both of the trim pots turned all the way up?
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All voltage checks were in the appropriate ranges. Trim pots were not turned all the way up, they are both all the way left. I cannot discern a difference with changing them.
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Oops! I meant humpots, both trimpots turned all the way up.
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One common problem that we find sometimes is that some speaker spades don't always fit well into our binding posts, so I would start there.
Otherwise the path of debugging your issue would involve likely both posting some photos of the build of the non working channel, as well as potentially playing a 60Hz tone into the amp and taking some AC voltage measurements in certain spots to see where the signal isn't making it through.
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I am not using spades, just putting the speaker wire into the posts, but that has always been fine in the past for me. Here are some pics of the full build I took. I am wondering if my connection to the right input is not so good. When I turn the amp on I hear the low-pop from both speakers if that helps with anything.
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Also, I can take more in-depth pics if needed.
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I am preemptively adding some more pictures of the right channel.
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The two things I see are a strand or two of wire hanging around the trim pot that may be shorting the signal out, and possibly the center pin connection to the RCA jack is low enough that it's touching the outside portion of the jack.
What DC resistance do you read across the RCA jack? Something well below 100K would confirm one or both of the above are causing some problems.
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What two points would I measure to read across the RCA jack?
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The center pin and the outside.
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I am getting 100.4 with my meter set to "200K" in the resistance section. Is this normal?
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That is what's expected.
What I would suggest is picking up a meter with a lower AC voltage setting, an old phone/tablet with an 1/8" headphone out, and an 1/8" to RCA adapter.
Harbor Freight has a meter for about $25 that can resolve low AC voltages.
With these items in hand, we can trace signal through your amp.
One other thing you could try is to unscrew the C4S board and tilt it up out of the way a bit, then post a picture of the 9 pin socket wiring.
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Is this meter sensitive enough to use? Borrowed from work but can grab a different one if need be. I will also have the RCA adapter tomorrow, so I can run the tests.
Another thought - I am also using a newly completed but never tested Beepre2 that I built. Is it more likely the problem is occurring in the Kaiju? The BeePre passed every voltage test on the first go.
I am also attaching some photos of the D-socket.
Let me know what you think, and thank you for walking through all of this with me.
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Forum is being weird about me posting pics, not sure why!
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Nope, that still has a 200V minimum scale.
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Files too big maybe!
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One more, sorry about all the individual posts for the pics! Will grab a more sensitive meter tomorrow.
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I don't see anything in there. A higher resolution meter and a 60Hz tone will be required to figure out which half of the amp to look at I think.
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Ok sounds good! I am happy to start running a test after work tomorrow and I should have everything by then. Is the tone an audio file? When you are able to, let me know the first steps so I can report back once I have the opportunity.
Upon further inspection, it looks as if A5 and A4 were potentially touching, would that cause the problem? All of those terminals move around a bunch so not sure if it was leaning up against it.
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If A5 and A4 touch, that will also throw off the DC voltages, but certainly I would do some trimming if they look close.
The first test you can do with the amp off, which is to measure the AC voltage between the center post of the 9 pin socket and ground (you can use the shell of the RCA jack) with the trim pot all the way up.
I typically use a free tone generator app on an old phone to get the 60Hz file. You can also use a laptop with a headphone jack and grab a tone generator webpage. Your DVM will read 60Hz AC, and typically I'd expect about 0.3V of signal to be available.
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Once I get the meter, I will measure this! Should all tubes be in place for these tests? Is the tone playing in this test or no?
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Yes, the meter will measure the 60 Hz tone as AC voltage.
For the first test, the tubes don't need to be in and the amp can be off.
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Hey,
Just did the test, am reading .191V of AC going from the center pic of DSocket and using the RCA grounding jacket as the other point.
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OK, now also check the voltage at the center pin of the RCA jack. 200mV is certainly enough to work with!
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Assuming you have about 200mV of signal at the center pin of the RCA jack, the next step is to fire up the amp with the tubes in it and check the AC voltage at pin 3 of the 300B tube socket. A normal working amp with the trim pot turned all the way up and 200mV of signal at the input is going to give something like 5-6V of AC signal at pin 3.
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If the AC voltage appears at pin 3, you will then want to measure the AC voltage across terminals 5 and 10 of the output transformer (these have the red/white twisted pair of wires connected to them). If you have 5-6V at pin 3 of the 300B socket, you'd expect to see 3-4 times that across the output transformer. You have to move the black probe because the output transformer primary is sitting at about 70V DC, and your meter may not see the AC voltage through that.
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Getting .241V of AC from center post of RCA to Grounding jacket. I need to head back into work, but will be running the next test once I get home around 630 EST!
Thanks so much for your help!
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When I am checking the voltage of these pins and terminals is the blackprobe staying on the RCA grounding source? or is it moving to other areas? WHat do you mean move the black probe?
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The black probe can stay on the RCA ground until you measure the last AC voltage at the output transformer.
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Here are the measurements:
B3 and RCA ground = 5.8V AC
Terminals 5 and 10 = 21.34 AC
Sounds normal, right?
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Now measure the AC voltage across the speaker jacks.
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Between the two output jacks, it's 1.133V AC
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If that is a correct measurement would it make sense to assume that the problem could be stemming from the Beepre? I tried playing both the Beepre and Kaiju for the first time in the same go.
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1.133V AC is audible signal coming out of the speaker jacks. This confirms that the amp is working. I would hook it back up and have a listen.
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No right channel still. So we can assume the Kaiju is fine? Other thing is a BeePre2 I built right before the Kaiju.
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Try swapping cables from the beepre 2. If the problem switches sides the amp is good and you need to focus on the cables or preamp.
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Swapped the cables, the problem still persists.
Thanks for the recommendation, though! I appreciate it.
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Play the 60Hz tone into the Kaiju hooked up to your speakers and measure the AC voltage between the speaker binding posts.
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Played the tone directly from the 1/8 to RCA into the kaiju, bypassing preamp. I could hear it out of the speaker fine.
Voltage was .305V w 60hz tone.
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Now feed the tone into the BeePre and hook it up to the Kaiju.
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I am getting nothing. Voltage says 0.
I am also no longer getting any sound out of the left channel from the Kaiju either from directly playing the tone thru 1/8-RCA into Kaiju or from BeePre to Kaiju. Both of those were working an hour ago.
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Now that you have lost the channel, I would restart the checks you just completed.
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Out of left channel:
.121 V AC center d to RCA Ground
.76VV AC Center RCA to RCA Ground
I am getting 0 when checking C3 to RC Ground, though.
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You appear to have substantial loss between the RCA jack and the center post of the D jack. What's the AC voltage at the center pot lug?
0V at C3 means the signal isn't making it out of the 5670 stage. I would expect a DC voltage to be off on the C4S board if signal isn't getting out of here, but admittedly that's not always the case.
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Center lug of trim pot and RCA ground = .759 V AC w Tubes in, powered up, and 60hrz tone playing.
Tubes in, powered up, and 60hrz tone playing, using safety ground for all.
IA=298VDC and
OA=443VDC
IB= 297.6 VDC
OB= 181.3VDC
KregA= 3.495VDC
KregB= 6.5VDC
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Can you post a photo of 4 pin socket and the 0.1uF cap mounted behind it?
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Here it is!
Thanks!
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Ok, on that strip if the 0.51 ohm resistor touches the resistor going to A3, you'll destroy your 300B, so I would slip those 0.51 ohm resistors in toward the 4 pin socket some more.
Where the 0.1uF cap lands on the terminal strip on the 4 pin socket it looks like you need a lot more solder and heat. Where the white wire jumps from there 5 pins over looks like it could also use a bit more solder.
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Made those adjustments!
Reading 23V AC from RCA ground and C3! That's with the tone and tubes in place as well as powered on.
That's the correct measurement, right?
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Yes, that is a promising change.
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Is the next step putting it back in the system?
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I still need to figure out why my right channel won't play once everything is hooked together. If this amp can play both channels directly from RCA(computer hookup) to speaker, then would it be reasonable to think it's the pre that needs some adjustments?
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It's possible that you have something that's loose and flipping the chassis plate around is moving the intermittent connection.
Once you put the Kaiju back in your system, you'd want to play the 60Hz tone back into it directly to ensure that it's still passing signal before looking for problems elsewhere.
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Played the 60hrz tone and heard it fine from both speakers! Should I take any more readings or anything before we start looking elsewhere?
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If you can play the tone through the amp into your speakers, then you need to hook the BeePre up and try with that.
If you only get one channel of output from the BeePre, swap the interconnects at the BeePre to see if the dead channel moves to the other side of the Kaiju. Be sure to try both cables on both channels to rule out cable problems.
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Already tried both cable swapping and hooking into the BeePre again. Swapped all my interconnects for other RCA's I have around 'n such. The right channel is still gone, unfortunately.
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If you take your BeePre and feed the left output into the right channel of the Kaiju, does that work?
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Left for work but will update when I am back!
Thank you !
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I plugged the left out from BeePre into the right input for Kaiju and music is playing out of the right side. I also checked all of the other inputs and right out will not play from any of them.
Would that mean the problem is stemming from the right out of the BeePre?
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Try the other cable between your BeePre and Kaiju to be certain it isn't that particular interconnect that's causing the problem, otherwise you'll need to delve into the BeePre a bit.
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I have swapped with other cables and the problem is still persisting. What would be the first step with the BeePre?
On the flip side, I have my Dac+streamer hooked into the Kaiju directly and it sounds FANTASTIC. Thank you for talking me thru this so far.
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I would start with a voltage check. Is it a BeePre 1 or 2?
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It's a BeePre2!
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What are the voltages on each 300B socket in your BeePre?
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I measured the following values w the ground next to the IEC for the black probe.
A1 14.08 vdc
A4 9.21 vdc
B1 8.94 vdc
B4 13.96 vdc
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How about pins 2 and 3 on each socket?
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Here they are!
A3 .9mVdc
A2 91.9Vdc
B2 93.7Vdc
B3 .6mVdc
No tones playing or anything, just tubes in, powered up. Same ground as the last test.
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OK, well now we get to do the same test to your BeePre that we did with your Kaiju.
You can do the first one with the BeePre off. Play a 60Hz tone into the inputs, center the balance control, then read the AC voltage at pin 3 on each socket. (If you have the first upgrade installed you can just play the tone and see what AC voltage appears at pin 3 on each channel)
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.009V ac B3
.012 V ac A3
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Is that with your test tone all the way up?
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I guess not! Here is the tone all the way up.
B3 .395vAC
A3 .382vAC
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OK, now turn the preamp on, turn the level controls all the way up, then measure the AC output from each output RCA jack.
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1.496Vac LO
.491Vac RO
Using the ground for each respective RCA jacket.
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OK, how about the AC voltage for the upper and lower lugs on the volume pot that are closest to the rear of the chassis?
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Upper 1.502 V ac
lower .381 V ac
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Can I see some photos of the build on the weak channel? The numbers you're posting indicate a weak channel, but not completely dead.
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I think this is the right channel, right?
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You need to add more solder and a lot more heat to the joints in this kit. The sound likely isn't making it out from solder joint issues.
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Makes sense, this was the first one I built. Should I just go over all of em adding more?
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Yes, don't forget to add more heat too so the solder flows out properly.
https://www.youtube.com/watch?v=EN16Pi7pcfk (https://www.youtube.com/watch?v=EN16Pi7pcfk)
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I have gone over every joint on the right side around the 300b socket and I am still not getting a full signal. Any suggestions for areas to pay more attention to?
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You can do another 60Hz AC signal measurement and look for the AC voltage on the rear lead of each 10uF cap (not the forward lead that wires to each 4 pin socket).
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L 1.481v ac
R .332v ac
Attaching the pics of resoldered joints. Thanks!
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I suspect that the blue capacitor on the weaker channel is loose on one end (or both).
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I have re-soldered all of the joints and I am pretty sure nothing is loose at this point. Still getting a much weaker signal from that channel, its pretty hard to pick up any AC signal from the outbound lead of the 10uf Cap. I am attaching resoldered pics just in case I am missing anything else. Other than that are there any other troubleshooting measures I should be doing?
Thanks!
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You have the output shorted with this wiring error.
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:O wow, its fully playing thru both speakers now. Thank you so much for walking me through this really long troubleshooting situation. It's silly it was a miswiring, but I am extremely grateful for your help and responsiveness.
One last question I have about the BeePre now that it is in the system - There is a small buzz that happens when I turn the volume past 75% or so. The Kaiju plugged in by itself was nearly silent. Is this the gain of the BeePre? I have the Bee2Quiet attenuator upgrade on the way now, would that remove some of that?
Thank you again, so much!
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Replacing the 130 ohm 2W resistors with 27 ohm 2W resistors can take that out, as will the second upgrade that we are releasing shortly. The noise shouldn't be intrusive under normal listening conditions.
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Yeah, it pretty much disappears once the music is actually playing. If I were to swap out the resistors would that impinge on the new upgrade down the pipeline at all? Is there a specific resistor/brand you'd recommend?
Thanks!
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Just found your post on it! putting in that order! Thanks PB!
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What's the time frame of the second update?
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I just received the missing pieces I need to build my BeePre out according to the manual instructions. I'm at the tail end of a flood of repairs (8 arrived in the span of 3 days!) and custom builds, then I can move onto this. One of those repairs remains, as do two Stats that need to get built first.
-PB