Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: preston.ezell on October 13, 2021, 08:05:26 PM
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So I received my crack 1.1 and followed the guide perfectly. It worked and sounded so good! I was smiling from ear to ear listening to it with my HD6XXs. I ordered the crack with the speedball upgrade because of all the sound quality claims. Today I finished the speedball installation and everything measured correctly. I lost the Manuel file so I can’t remember what voltages I was supposed to have on everything, but something has gone terribly wrong. I don’t have any sound in my right channel. The left sounds good and without issue, but I have no right channel. I tried everything I know to do.
What happened to the repair service? I need the doc.
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Oh we still offer the repair service, but we hope that people can come here first for help, and that we can see a pic or two of any build before it gets sent in. In your case, you could post your DC voltages on terminals 1-10 and we might be able to make some suggestions about what's going on, and build photos may also help us spot something too.
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Okay, I can check these terminals when I get home from class. My initial crack 1.1 build complied with the expected values, so something definitely when wrong with the speedball installation.
I’m hoping I can get ahold of another pdf
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I mean you can post your voltages on terminals 1-10 here and we can go from there; the Speedball manual itself isn't 100% necessary.
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I'd definitely post voltages when you get back irrespective of whether you have the manual. I'd also try and fix it before you ship it to Bottlehead. Paul does great work, and I mean no disrespect in saying this - I don't think he'd disagree with me - but it's vastly cheaper to fix it yourself.
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Just post those voltages for terminals 1-10 and a good clear photo of the Speedball board installation. If you do that you needn't worry about resistors or manuals, and probably won't need to worry about repair service. If you can build it you can probably fix it.
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https://drive.google.com/drive/folders/1-0pw9LZF-D7ueBELUtM92PAhR_sd-lLd (https://drive.google.com/drive/folders/1-0pw9LZF-D7ueBELUtM92PAhR_sd-lLd)
Here’s what I have vs expected for both crack and speedball readings.
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I think you have a backwards PN2907A transistor (Position Q1A) on the front board, left side (A side).
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YES, Q1A small board looks to be BAKARDS.
Chris/AB2KH
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Isn't the internet wonderful sometimes - diagnosed in 20 minutes, confirmation in 24. For free!
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HOW DID I NOT SEE THIS. I was so careful. Lol
I will flip this when I get home and see if any other problems creep up. Will update tonight after my lab. I am currently studying the photoelectric effect for my physics lab lol now I’m nervous that I’ll never understand it based me overlooking something so simple as this. You guys are awesome. I love the internet.
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A neutral set of eyes can very often see things you can't, you become "astigmatised" as to what you are working on. If I may add one constructive criticism - you should not paint the component side of your chassis plates it can cause connectivity issues.
Chris/AB2KH
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For that particular error I think the symmetry has something to do with not seeing it.
The two transistors are currently mirrored (incorrectly) so, once installed, simply don't look out of place alongside everything else also mirrored (correctly)
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I will always accept constructive criticism. I actually painted this side by accident. I thought it was the top when I started. Doh
And the symmetry is what I too expect to be the reasoning behind this. Everything else is installed in pairs with a mirror image. So expecting to find a component that opposes that rule was not on my mind.
Just got out of class. I look forward to seeing what happens next!
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Well done!
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So it appears that flipping the transistor did not solve my issue. I still have 0 voltage at terminal 1 and 0 voltage at OA
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I checked the resistance of my 150kohm 2W resistors on the small board and the A side resistor is reading a varied amount that doesn’t really go above 25kohms.
This resistor needs replaced, right?
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So I got a stable reading. Seems the a side 150kohm resistor is reading 55kohms max.
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I guess I need replacement parts for my small board. How do I go about ordering these?
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Woah, slow down a little. A 55K resistor would actually work fine there. There's also not really a failure mode to kill that part.
In the photos you posted of the build without the C4S board, there is what looks to be some metal material between pin A5 and pin A6. If those pins touch, you'll get 0V at terminal 1.
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I will fix that up and report back
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https://drive.google.com/file/d/184z_3Cc_rhvlpwYzjt_lUdikP2IH2Vjg/view?usp=drivesdk (https://drive.google.com/file/d/184z_3Cc_rhvlpwYzjt_lUdikP2IH2Vjg/view?usp=drivesdk)
No metal between A5 and A6
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https://drive.google.com/file/d/1hjTsypy68VWYzLWrddYGwOU9p6bKoZEw/view?usp=drivesdk (https://drive.google.com/file/d/1hjTsypy68VWYzLWrddYGwOU9p6bKoZEw/view?usp=drivesdk)
Another angle of between pin A5 and A6
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So I have a voltage reading at OB on the large board without the amp being plugged in, is this supposed to be happening?
https://drive.google.com/file/d/1dnbaZ1RjwL-SR0mXSRfe0FVfG6lflLGN/view?usp=drivesdk (https://drive.google.com/file/d/1dnbaZ1RjwL-SR0mXSRfe0FVfG6lflLGN/view?usp=drivesdk)
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I have 0V at B7 and B8. I’m not sure if I’m supposed to have any.
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At this point you'd want to focus on the small board not working properly. You can even unplug the 6080 for now and just run the amp with the 12AU7.
Can you do a DC resistance check between terminal 1 and ground?
Generally when a C4S board fails to function, we see high voltage on the output and resoldering is required. Seeing 0V on the output is more typical for the output being somehow shorted to ground, which suggests debris or wire ends touching as a cause of the problem.
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Paul, it's incredible just how knowledgeable you are about virtually every single scenario concerning the circuit and troubleshooting. I mean I know you're a designer lol, but still... Hats off to you for all your help :)
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I've just messed up my fair share of builds.
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https://drive.google.com/file/d/1N7cLJOaOmDVxd7CEYkkrzWS3HM5_kYKl/view?usp=drivesdk (https://drive.google.com/file/d/1N7cLJOaOmDVxd7CEYkkrzWS3HM5_kYKl/view?usp=drivesdk)
Is this correct?
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34.3k ohms
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This is with the 6080 unplugged, btw
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How about the same measurement on terminal 5?
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https://drive.google.com/file/d/13Cy4hq923tAkbmj7nLxxVBiKpKtCFmKy/view?usp=drivesdk (https://drive.google.com/file/d/13Cy4hq923tAkbmj7nLxxVBiKpKtCFmKy/view?usp=drivesdk)
0L
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Is it possible the junction of the 2907 was damaged ?
Chris/AB2KH
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https://drive.google.com/file/d/1qTdLVCjuhDLUKdV2IXVHmoLY5ynbcnas/view?usp=drivesdk (https://drive.google.com/file/d/1qTdLVCjuhDLUKdV2IXVHmoLY5ynbcnas/view?usp=drivesdk)
2907
I did have to de-solder and flip this transistor.
There is a small voltage going through my A side 2907 and about 100+k ohms of resistance
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I have a -0.4V at A7. My led there is also not lit. It was before the speedball
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Not to confuse the issue with facts, Your reply post #28 and #32 photos IMG4686 & IMG4687 Indicate that your amp is ON and your meter (looks like) it is set to ohms/resistance. If infact you are looking for a resistance reading the amp should not be ON. On the other hand if you are trying measure voltage then your meter is not set to the correct position.
Chris/AB2KH
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https://drive.google.com/file/d/1s3cg-cC4pEu_gMxkMnfLHigXYracccgp/view?usp=drivesdk (https://drive.google.com/file/d/1s3cg-cC4pEu_gMxkMnfLHigXYracccgp/view?usp=drivesdk)
https://drive.google.com/file/d/1PhDFCLMSEH-wQ5ZMHsJ-1Zj5lHr8hk5l/view?usp=drivesdk (https://drive.google.com/file/d/1PhDFCLMSEH-wQ5ZMHsJ-1Zj5lHr8hk5l/view?usp=drivesdk)
Sorry, you are correct! I accidentally had the amp on during my resistance measurement.
Here are the correct/proper readings.
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PB is the expert here! and I agree you should focus on the small board at this point.
My amp has the old style boards so the connection identifiers are most likely different but the circuit I believe is the same. So hopefully you can follow by following the schematic.
The point at which the B+ connects to the the small board should be somewhere around 170 VDC (at least on my schematic) now if you measure the point at which the board connects to the plate of the 12AU7 you should see about 75VDC (at least on my schematic). You should be able to confirm these voltages from the working side of the board.
If you don't have 170 VDC on the in put you have a power supply issue.
If you don't have close to 75VDC on the plate of the 12AU7 then there is / are faulty components on that side of the board or a grounding issue between the cathode and ground. You did say it was working before speedball so that most likely is not a problem.
My money is on the 2907 being damaged either from incorrect installation initially or from heat damage during extraction and re insertion.
I hope this helps
PB you have the floor.
Chris/AB2KH
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I am a bit concerned that I damaged the 2907 from the de and re soldering I did.
The legs got pretty hot in order to extract it. Is there anyway I can test directly whether or not that transistor is damaged?
I’m at work right now, but when I get home I can check these values and see if they’re around what’s expected.
This is my very first experience with any of this stuff, so I’m learning quite a bit all at once. It’s both exciting and frustrating.
I’ll let you know what I find tonight after work.
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You could certainly try replacing the PN2907. You could also contact replacementparts(At)bottlehead(dot)com and ask for a new small board and small board parts.
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I will go ahead and get the small board replacement and go from there, I suppose.
:( lol I almost wish I hadn’t heard it before I goofed. That way I wouldn’t have known how it sounded before losing it.
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So I've made an observation. The middle leg of my A side MJE350 has no voltage. You can see this in the photos below. I tested the three legs of each MJE350 and noticed that only the middle leg of the A side does not give a voltage reading. I thought that this perhaps may be due to a problem with the transistor, so I switched the A and B side, and still am not getting a reading from the middle leg. Earlier it was proposed that the 2907 was damaged from the resoldering, but I have checked all of the legs for the resoldered 2907, and they all have a voltage reading.
I'm not sure if this really means anything, as I don't have any prior experience with circuits like this, but it feels like to me that these readings mean that there isn't really a problem with the small board, and it seems the 0V reading at terminal 1 is due to something somewhere else in the circuit.
So, IDK. Let me know what you think.
https://drive.google.com/drive/folders/1zyGib1GURGJ0z39O52nla8TNa_0DoxiH?usp=sharing (https://drive.google.com/drive/folders/1zyGib1GURGJ0z39O52nla8TNa_0DoxiH?usp=sharing)
-preston
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The 0V reading would be consistent with a short dragging down the output of the C4S board. You might check the wire going from terminal 1 to B1. If the insulation is melted and it's touching B8, that would cause this problem. It looks quite a bit longer than what it needs to be, so it's hard to tell what it might be touching or if it perhaps got touched with a hot soldering iron somewhere along its length and is making contact where it shouldn't.
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I just went over the entire circuit and quadruple checked to make sure there are no connections being made where they are not intended to be made. I have no idea anymore. Sad day.
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And @AB2KH as a direct response to what you were suggesting, I measured and I have around 207V at the point where the B+ connects to the small board. I have around 75V where the board connects to the AU7 plate from terminal 5. I have 0V where the board connects to the AU7 plate from terminal 1.
So perhaps this will come down to a replacement of the small board.
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You can e-mail queen(at)bottlehead(dot)com to request a repair box. Be sure to paste a link to this thread so she knows you've been here.
-PB
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Put your amp in the base as you would operate it. Place it in a dark area and turn it on, cheque the 12AU7 and confirm that both sides of the tubes heaters are glowing orange, you should see two of them one for each triode section.
Let us know the results.
Chris/AB2KH
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Last time I did this check both were glowing, but I will check again after work and report.
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My thinking in my previous post is not sound so please disregard it.
You have supply voltage but no output voltage and the LED's are not lit and they should be on regardless of wether there is a plate load present or not. So that would confirm that there is/are components that are "tutafineut". PB is correct, the best/easy answer is go for a new board and parts.
I would be curious as to the final results so keep us posted.
Chris/AB2KH
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So, although they might be dim (I’m not sure of what brightness level would be considered normal) both sides are lit.
https://drive.google.com/file/d/1a00w5hmAVk5NLZ5j4J2NKWaBUBzQ7H_H/view?usp=drivesdk (https://drive.google.com/file/d/1a00w5hmAVk5NLZ5j4J2NKWaBUBzQ7H_H/view?usp=drivesdk)
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Touch up the solder pads on those LES's they look a bit sketchy
Chris/AB2KH
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I’m sorry if this is a dumb question, but again I’ve never done this sort of thing before.
What is the LES?
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Did you mean LEDs?
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I think AB2KH meant LEDs, and I suggest not touching them up yet - they are so small they can easily be overheated.
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Good day all,
Yes I meant LED's, sorry for the confusion. Paul my thinking was and is at this point he really has nothing to loose.
Chris/AB2KH
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I got this repair on the bench today, and the PN2907 did not survive being installed backwards and was shorted out, and this pretty much tanked that half of the small PC board up front. One LED on the 9 pin socket was open also. The LED problem and some other soldering related issues look to be from using an iron that's not hot enough to properly flow out the solder quickly.
Fixing up the front PC board, I was then left with one dead channel and one half of your rear PC board that just wasn't passing any current. When I unscrewed your rear board and moved it, all of the wires broke in a way that's consistent with using a wire stripper on too small of a setting, which will cut into the solid core wire and weaken it so it snaps off. When I went to work replacing these, I discovered that all of the wire ends going to the terminal strips were just resting on the terminal strips with some solder, not passing through the terminal strip holes themselves, so I had to replace every wire required for Speedball installation because connections like those are likely to pop loose later on their own.
After installing all of the new wires, there was also some distortion in the previously working channel which I tracked down to a damaged transistor on the other side of the large PC board.
With all of those issues addressed, this amp is now up and running.
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So thorough, nice work, Paul. :) Hope you had some good coffee beforehand!
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I split the work between two different days, so that helped a lot!
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Paul,
Thanks for your up date on this mystery. From the sound of your repair report this thread could have gone on for ever.
Preston,
Hope you enjoy your amp, it is truly a top shelf piece of audio equipment.
Chris/AB2KH
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I’ve been so busy with school. I’ve only just now gotten around to checking the forum.
First of all I can’t thank Paul enough for fixing everything up. I’m really looking forward to getting it back.
The iron I used initially was quite old, so this makes sense. I borrowed it from my physics professor’s lab equipment and he said that he had no idea how long it’d been there, but it was long before him. (It looked quite old).
My wire stripper too was a very crude tool. I got this from my brother. The size of the stripper was adjustable only by changing the position of a screw that served to modulate the maximum amount of squeeze that you could apply to the handles..
So, two major lessons that I learned:
don’t use cheap/improper tools just because someone lent them to you
Go slow and take breaks often
I assembled (attempted to assemble) the amp and speedball over the course of a 18ish hour sitting.
Thank you to everyone else who was so readily available to help me work through the issues and diagnose the problem.
I can tell this is a special place. I’m happy to be the owner of a product from this kind of community.