Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: Rhok on April 04, 2014, 12:59:20 PM
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Hello Everyone!
I really hope someone can assist me with this, as I was so stoked for this project (and it was my tax return "gift", being only 22 living on my own in this economy this was a major investment for me!)
I'm failing resistance checks on terminal 13, potentially 20 (mixed results) and the center pin. Now before I continue, I'll admit I'm a total noob but am fairly technically inclined (not so much with electronics! but computers) had experience soldering, and generally fairly capable. But this particular project when it's gone south now I'm totally lost on where to begin troubleshooting.
I'm hoping someone here could assist/advise me on making my amplifier work - it's been such a crushing feeling to have issues after assembly!
Here are some general photos of my build to see if anyone notices any major issues that I didn't catch - additionally I had to replace the 270K 1W resistor because I had accidentally broke off one of the legs of the original don't know if that's part of the issue - the resistor itself reads correctly on a multimeter.
http://s752.photobucket.com/user/mikemathis3/library/
I can provide additional photos/will try anything, am low on materials but I need to get this to work I can't imagine abandoning the project.
Any help/advice is very much appreciated.
- Mike
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Give us resistance readings and we can start to sort it out.
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Most definitely,
Before I provide the readings, as long as I'm grounded on the negative can the positive touch any part of the terminal to receive an accurate reading, or should I be placing it somewhere specific?
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Well, the qualifier is if the solder joint at the terminal is good, then yes, touching the probe anywhere on the terminal is fine. If you think you have a bad joint, try touching the terminal with the black probe and the lead connected to it with the red probe. If you measure a high resistance you have found a cold solder joint and needs to be reflowed.
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1: 0.4
2: 0.4
3: 0
4: .35
5: varied 1.5 and dropping, or above
6: 2.483
7: 2.951
8: 000.7
9 2.934
10: 2.485
12: 000.9
13: 3.2 - very varied, but nowhere near 270k
14: 001.0
20: 0.650
22: 000.8
B3: 2.953
B6: 2.934
Ground Lug: 000.8
RCA: 098.4 on both roughly
Center pin: 000.6
I'm using a Fluke 87 True RMS Multimeter which is very sensitive not sure if that's part of those 0's not reading a straight 0.
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It's pretty important to have units along with these measurements.
0.4 could be 0.4 Ohms, or 0.4 Mega Ohms, which would be 400,000 Ohms. You have an unusually nice multimeter for these measurements, it looks like it will just tell you what the units are. For example, I see 2.951 and 2.934 on 7 and 9. These are certainly in thousands of Ohms, which makes them OK. (6 and 10 are certainly about the same)
Also, that meter will certainly measure the resistance of the wire in the leads.
The carbon composition resistor is not a particularly wise choice for the bleeder, can we send you a replacement?
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I have the multimeter's dial simply set on the Ω symbol for the measurements I'm providing. So I anticipate they are all Ohms and not Mega Ohms, how could I confirm the difference? I listed them exactly how they showed up on the multimeters display.
Of course I would accept a replacement - I had a hard time finding anything other than carbon for a 1W 270K resistor for my local and online search (unless it was coming from China).
I didn't bother to contact you guys in regards to that since it was my fault. Then again, the issues I'm experiencing are also my fault for not building the amplifier correctly - but now I'm desperate for any assistance lol.
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The meter will display a "K" or an "M" next to your value when it's not just Ohms. It looks like they should appear near the bottom right corner of the display.
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I really appreciate the help - like I said, when it comes to this stuff I'm a complete noob.
Here are fresh results with appropriate markings.
1: 0.4 M - Varied results
2: 1.5 M - then it will continuously drop, varied as well. (did not encounter this last time)
3: 000.7 (does not read K or M)
4: Started at 0.600 M - descreases 1 per second - get very mixed results here as well
5: Started at 2.6 M - drecreases rapidly - also did not experience this last time.
6: 2.483 K
7: 2.951 K
8: 000.7 (does not read K or M)
9: 2.934 K
10: 2.485 K
12: 000.8 (does not read K or M)
13: starts at 0.600 M and slowly decreases.
14: 000.8 (does not read K or M)
20: starts 1.6 M and slowly decreases
22: 000.7 (does not read K or M)
B3: 2.951 K
B6: 2.934 K
RCA: 98.4 K (for both again)
Ground: 000.9 (does not read K or M)
Center: 000.8 (does not read K or M)
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I think you're ready for voltages.
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Tubes did not glow, the fuse is not blown (no visible detection and less than 1 Ohms reading on multimeter). Disconnected everything (as listed in the PDF instructions) - now what should I do?
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Test the AC voltage at the power transformer. With the amp plugged in and powered on, you should get:
120V AC between power transformer T1 and T2
6V AC between power transformer T4 and T5
160V between power transformer T6 and T7
The 6V between 4 and 5 makes the tubes glow, but you won't get voltage there unless the incoming voltage at 1 and 2 is correct.
Do also note that there are two positions in the fuse holder that accept a fuse. One is a storage box for an extra fuse, the other is a clip that is where the fuse needs to go for the amp to power on.
-PB
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Here are the latest results:
T1-T2: 123.1 AC
T4-T5: 6.58 AC
T6-T7: 179.1 AC
Additionally, I took a picture just in-case somehow this is not where the fuse is supposed to go - though there's no other way for it to make a connection otherwise. http://i752.photobucket.com/albums/xx165/mikemathis3/IMG_0710_zpsd18cdd37.jpg
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The 6.58V means that the tubes should glow. I would inspect the twisted pair of wire leaving power transformer terminals 4 and 5 and going to B7/B8. Wrap them around the solder tabs on the transformer and be sure they are well connected on both ends.
-PB
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Awesome, we're getting somewhere (the tubes glow! - it was awesome to see the filaments start to take life), one of the wires on B7 was not properly soldered - how easy it is to track something down if you know where to begin looking. I would presume to move forward with the voltage checks from here, but I will await further instruction. Additionally, I am not sure if the LED(s) should also light up at this stage, but they do not.
FYI I'm very impressed by the customer support for a DIY project, I feel confident that this will function in the end thanks to the provided assistance.
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If you find a cold joint it's often best to simply reflow the solder on every terminal. If you do this before you spend a lot of time trying to analyze the exact location of every problem it can narrow things down.
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Yes, please proceed with the voltage check.
LED's not glowing on the 9 pin socket can be caused by several things, which we can help you work through. There is this great temptation to try to reflow the solder holding the LED's in place, but this is almost always not the issue.
-PB
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Okay, I went with Doc's recommendation to reflow the solder on every terminal and I'm very confused with my voltage checks, something seems very off - and either I am not properly using the multimeter to test, or there is some major misconfiguration of my crack. (wish I wasn't such an electronics noob, this experience will definitely make me want to learn/understand more - hate being clueless in a situation)
Anyways, here they are - or something' -
1: 2.0 m V AC
2: 1.1 m V AC
3: 1.0 m V AC
4: 1.1 m V AC
5: 2.0 m V AC
6: 1.4 m V AC
7: 1.4 m V AC
8: 1.2 m V AC
9: 290 m V AC
10: 1.6 m V AC
11: 2.0 m V AC
12: 1.0 m V AC
13: 1.4 m V AC
14: 1.2 m V AC
15: 1.4 m V AC
20: 1.4 m V AC
21: 1.4 m V AC
A1: 2.7 m V AC
A2: 183 m V AC
A4: 14.6 m V AC
A5: 14.6 m V AC
A6: 175 m V AC
A7: 1.3 m V AC
A9: 6.15 m V AC
B1: 240 m V AC
B2: 1.4 m V AC
B3: 160 m V AC
B4: 140 m V AC
B5: 1.4 m V AC
B6: 1.4 m V AC
B7: 250 m V AC
B8: 240 m V AC
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Reread pages 38 & 39 of the Crack assembly manual. Your meter needs to be set for DC and if not auto-ranging, about 400volt range. All of your voltage readings are VAC when they should be VDC. The only AC readings, (not in millivolts), should be the heater wires on the octal, (7 & 8 ) and 9-pin, (9, 4 & 5) sockets, (See pages 18 & 19 in manual). All other voltages are DC.
Report back any DC voltages that are more than 10-15% off the manual benchmark voltages.
Cheers,
Geary
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Was anything lit up when you were measuring voltages - tube heaters or LEDS?
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Well I feel like an intelligent person - I will redo the readings on the correct multimeter settings when I get home.
And yes Doc, the tubes were glowing through the entire time - the LEDs were not.
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New results:
Max range set to 400
1: - 000.6 vDC
2: - 000.6 vDC
3: 0 vDC
4: - 000.6 vDC
5: - 000.6 vDC
6: 0 vDC
7: 0 vDC
8: 0 vDC
9: 0 vDC
10: 0 vDC
11: 0 vDC
12: 0 vDC
13: - 000.6 vDC
14: 0 vDC
15: - 000.6 vDC
20: 0 vDC
21: - 000.6 vDC
A1: - 000.6 vDC
A2: 0 vDC
A4: 0 vDC
A5: 0 vDC
A6: - 000.6 vDC
A7: 0 vDC
A9: 0 vDC
B1: - 000.6 vDC
B2: - 000.6 vDC
B3: 0 vDC
B4: - 000.6 vDC
B5: - 000.6 vDC
B6: 0 vDC
B7: 0 vDC
B8: 0 vDC
And on auto range:
1: - 0.679 vDC
2: - 0.680 vDC
3: 0 vDC
4: - 0.682 vDC
5: - 0.684 vDC
6: 0 vDC
7: 0.012 vDC
8: 0 vDC
9: 0.014 vDC
10: 0 vDC
11: 0 vDC
12: 0 vDC
13: - 0.665 vDC
14: 0 vDC
15: - 0.663 vDC
20: 0 vDC
21: - 0.661 vDC
A1: - 0.666 vDC
A2: 0 vDC
A4: 0 vDC
A5: 0 vDC
A6: - 0.665 vDC
A7: 0 vDC
A9: - 0.001 vDC
B1: - 0.664 vDC
B2: - 0.662 vDC
B3: 0.011 vDC
B4: - 0.663 vDC
B5: - 0.660 vDC
B6: 0.013 vDC
B7: 0.007 vDC
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I guess I'll state the obvious, something is wrong. If the tubes glow you should have about 6.3V AC on the heaters. You have nothing anywhere.
I'll assume that your measuring method is the problem. Voltage is read from one point to another. And depending on the reference it can change.
Get some jumpers, wire with an alligator clip on each end, from Radio Shack. Take a jumper and attach one end to the black lead of your meter. Attach the other end to terminal 3 or one of the resistor leads that are soldered to terminal 3. The resistor leads are easy to clip to.
Set your meter to AC volts and auto ranging, that is usually pretty good. Turn on your Crack and carefully use the red lead to read the voltage at the small tube socket pin 4, then pin 9. One of those should give a reading close to 6.3V AC.
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Hello Grainger,
Thanks for your input, this actually was how I was already making my readings - my multimeter has different leads, one of which is an alligator clip.
When measuring AC voltage, I do get readings - and when I switch to DC I get the readings I posted.
A4: 14.3 m V AC
A9: 06.14 V AC
I would definitely agree I am doing something wrong, or have the build wrong, but I am not quite sure of what that is. I'm really new to these kind of projects, and I really appreciate the provided assistance and patience with my situation.
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OK, set your meter to AC volts at its highest range and measure the voltage across power transformer terminals 6 and 7, and then measure across power transformer terminals 9 and 10. These are the terminals right on the power transformer, not the strips mounted to the chassis. For each pair of terminals it doesn't matter which test lead goes to which terminal, as you are measuring AC volts. You should see roughly 150VAC across either pair. If that checks out OK we will proceed to the rectifiers.
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Ok, those are good readings.
Try this, put one meter lead on transformer terminal 9 and one on transformer terminal 10. It is still AC. It should be about 150V AC but will probably be higher since it doesn't seem to be turning on the tubes yet.
And I see I was too slow, someone else posted that already.
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Hello guys,
As requested.
Between 6-7 and between 9-10, I get the same reading which is 174.6 V AC
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Ok, that's good. Now switch your meter to read DC volts on its highest range and measure the voltage at terminal 21. Touch the red test lead to 21 and the black lead to terminal 12 (which is power supply ground). You should see roughly 210 volts.
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My reading for this terminal is
21: - 0.665 V DC
Your instructions are about as simple as can be, so I don't think I'm measuring incorrectly, the value is just obviously way off.
Any ideas?
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OK, either the rectifiers or the meter is not working. I would be grabbing a backup meter right now, but if you don't have one try measuring the voltage of a known good battery to verify that the meter will measure DC voltage properly.
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Hmm, I grabbed a AAA rechargable battery and got a 1.321 V DC reading, so that would indicate that it should be reading DC voltage properly, what now?
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OK, this is a bit of a pain, but try disconnecting the 270 ohm resistor and the positive terminal of the 220 uF capacitor from terminal 21 and then measure the DC voltage at terminal 21 the same way as before, red to 21, black to 12. That will help determine if the rectifiers are bad, or if they are working Ok and there is a short to ground in the circuit somewhere after the rectifiers.
By the way, I have had meters that worked OK on lower scales but didn't work on the highest voltage scale. If you had it set to a lower scale when you checked the battery you might want to measure that battery one more time on the 400V scale. It won't be as accurate, but you should see at least 1V.
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How about posting a picture of the right and left sides of the terminal strip where the diodes are. We want to verify that the diodes are oriented properly.
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Doc, I will attempt your recommendation after Grainger reviews my pictures, additionally, while having my multimeter set to 400 range, testing the same battery yielded these results: 001.3 V DC.
Grainger, here are the pictures you requested: http://i752.photobucket.com/albums/xx165/mikemathis3/IMG_0719_zps273125bf.jpg & http://i752.photobucket.com/albums/xx165/mikemathis3/IMG_0718_zps0b94f959.jpg
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They are all correct. I also see the caps are oriented properly.
I'm with Dan, try reading the DC as he says and then directly. Try measuring DC from (always the black lead) terminal 21 to (always the red lead) terminal 20.
Also, I'm not positive that the AC feed is solid. Try measuring from terminal 18 to terminal 19.
Your transformer seems to work properly. The circuit just totally dead somewhere and we are right on top of it. It will come to light soon. Hang in there.
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I think I see a loose wire.
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You're the freaking man Paul! Excellent attention to detail, it was just making connection with the insulation instead of the wire. As soon as I saw what you saw I removed the solder from that terminal, readjusted the wires, and re soldered, we may be in business now I'm going to do another voltage check.
21: 205.5 V DC
Additionally - LEDs glow!
Will post more momentarily.
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New results:
1: 080.8 vDC
2: 165 vDC
3: 0 vDC
4: 165 vDC
5: 078.5 vDC
6: 0 vDC
7: 100.8 vDC
8: 0 vDC
9: 100.4 vDC
10: 0 vDC
11: 0 vDC
12: 0 vDC
13: 165 vDC
14: 0 vDC
15: 185 vDC
20: 0 vDC
21: 206.5 vDC
A1: 078.4 vDC
A2: 0 vDC
A4: 0 vDC
A5: 0 vDC
A6: 080.4 vDC
A7: 0 vDC
A9: 0 vDC
B1: 079.9 vDC
B2: 164.8 vDC
B3: 100.6 vDC
B4: 078.5 vDC
B5: 165.1 vDC
B6: 101.4 vDC
B7: 0 vDC
B8: 0 vDC
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Alright guys, it doesnt look like we're in the clear just yet - I tested the amp with a cheap pair of headphones I did receive audio (awesome! and thank you for getting me that far!) however, I'm not receiving any output from the right channel.
EDIT:
I've also took some additional pictures: http://s752.photobucket.com/user/mikemathis3/library/xx
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Maybe a longshot but tried to swap inputs?
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I did not, but I just tried - same issue.
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So You swapped inputs and still hear music on your left headphone speaker?
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I tried to plug the amp to my dedicated soundcard, a usb DAC, and onboard audio, tried swapping RCA jacks around, all resulted in left channel audio only.
If I connect the headphones directly to any of those devices stereo audio works in both channels.
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Your voltages all suggest that the amplifier would pass signal.
You can temporarily short together the middle lug of each level of the volume pot, then see if the amplifier will play from both channels.
If it does, you probably have some solder shorting out the right RCA jack.
If it doesn't, you probably have a loose wire feeding the right channel of the headphone jack.
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I believe this time around I checked the wires that should be relevant for the right channel very closely and do not see anything loose (or not making proper connection). I also don't see any solder that may bridge a connection to cause a short.
Could you please explain how to short the middle lugs of the volume pot for testing?
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If you have a clip lead, connect one end to the middle lug of the bottom row of the pot and the other end to the middle lug of the top row.
If you don't have clip leads, use a piece of wire and solder this connection.
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Hey guys!
I isolated the problem, it was the 3.5mm to 6.35mm adapter I was using, I found it around the house and noticed an "M" on the adapter moments ago (mono). I appreciate you guys sticking through my lack of general understanding and being patient with my problems.
Thanks to everyone in this thread that helped me come to a fully functioning Crack. Time to go do some listening. (paired with HD650's if anyone was interested)
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Ha ha, yeah, it's those external components that can be a real bugger. We run into stuff like this in the lab pretty often, it certainly helps to have multiple sets of eyes.