Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: senpai3330 on March 12, 2014, 06:51:32 AM
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Second time crack builder, somehow managed to not mess up the first time only to do it the second time.
I did resistance checks with one lead clipped to terminal 12 as recommended. Every resistance tested fine until I had the other lead clipped to terminal 20. The resistance was supposed to read 0, but it looked like it was climbing toward 270K similar to what it should've read had I clipped the lead to terminal 13. I thought it was weird everything else was fine and only this one terminal check point was off, so I went ahead and tried to do voltage checks anyway. Heaters were working, tubes glowed fine, but the first couple of check points all read ~1.0V instead of 90V, 170V, etc. I decided I should stop pushing my luck and turned it off.
I went back step by step, did continuity checks for each point to point connection and reflowed any of the duller looking solder points. Unfortunately, while I was doing this, I think I discharged one of the 220 uF capacitors (big spark) because my soldering iron shorted two of the rectifiers together (picture below).
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FLDvtHT6.png&hash=de6f3e82363df1d6dfc5fe179358b7b7deed02b2)
Is that enough to ruin the rectifiers?
Note: I did make the 5/6/10 revision, transformer terminal 4 was connected to 14U instead of 22L.
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The resistance on 20 still doesn't read zero and continues to rise.
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I assume that that is a grab from the manual not your second Crack in the picture. Did you solder with power on? Did you unplug? If you wait 30s the charge is very low on the capacitors. So unless you didn't wait or soldered with the amp hot (always a bad idea) you only zapped a little voltage.
Try testing the diodes using your meter. They should show a low resistance with the black lead on the striped end and high with the red lead on the striped end.
If one or more diodes test bad the UF4007 diode(s) could be blown. They are cheap, maybe 17 cents?
If you can source them locally you are back to work fast, or call/email Bottlehead for replacement parts.
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Something is very wrong if you got a spark on an amp that is not connected to power. Please post pictures of your actual build. Do you have the black wire connecting 20U to 14U?
Additionally, one resistance being wrong is a sign something is wrong with the wiring. It is not safe to power on an amplifier that does not pass resistance checks.
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Try testing the diodes using your meter. They should show a low resistance with the black lead on the striped end and high with the red lead on the striped end.
If one or more diodes test bad the UF4007 diode(s) could be blown. They are cheap, maybe 17 cents?
If you can source them locally you are back to work fast, or call/email Bottlehead for replacement parts.
I tested the diodes, they're reading ~560 ohms each, I don't know if that qualifies as low or if you're talking about ~0 as low. I'd probably just get them from mouser since I was going to get some other supplies as well. I'll call Bottlehead to verify, but I'm assuming it's just these UF4007 from Fairchild. http://www.mouser.com/ProductDetail/Fairchild-Semiconductor/UF4007/?qs=sGAEpiMZZMtbRapU8LlZDz3zbYnpxBJB5elDBydTRZE%3d (http://www.mouser.com/ProductDetail/Fairchild-Semiconductor/UF4007/?qs=sGAEpiMZZMtbRapU8LlZDz3zbYnpxBJB5elDBydTRZE%3d)
Something is very wrong if you got a spark on an amp that is not connected to power. Please post pictures of your actual build. Do you have the black wire connecting 20U to 14U?
Additionally, one resistance being wrong is a sign something is wrong with the wiring. It is not safe to power on an amplifier that does not pass resistance checks.
Again, I think the spark was from a capacitor that hadn't fully discharged yet. I'll post photos when I'm home later. I do have the black wire connecting 20U and 14U.
Thanks for the help!
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Update: I took the nuclear option and deconstructed a lot of the parts around the transformer area, especially anything to do with terminal 14U (overcrowding) and 20 (weird resistance).
I moved some of the wiring to 14L and installed the capacitor that goes across terminal 12 and terminal 13 on some short leads for now to free up some working space around there.
Resistances all check fine now! But I'm not sure if that's a valid statement with the rectifiers potentially dead. The tubes no longer glow when I turn the amp on now, I'm assuming dead rectifiers would explain that?
Small photo gallery: http://imgur.com/a/9FaIW (http://imgur.com/a/9FaIW)
The resistors and output caps toward the front are on messy long leads since I'm removing them and installing speedball/new caps after this troubleshooting is solved, but they haven't given me any issues.
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Have you checked the fuse?
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Have you checked the fuse?
Hi Doc,
I did pop out the fuse holder just out of curiosity earlier. The little filament inside looks the same as when I installed it so I'm assuming it didn't blow (melt?).
On a more general note, could someone confirm whether the 560 ohm resistance reading across the rectifiers is indicative of them failing?
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I would need the answer to these questions to tell you how bad the spark was.
Did you solder with power on?
Did you unplug?
Did you wait the required 30s?
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The amp was off and unplugged. I feel like I definitely spent more than 30 seconds looking over the amp before the short happened, but the spark still seemed kinda strong with a loud pop/crack noise.
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Then, if you have the discharge resistor in your power supply, a 270k IIRC, the voltage involved would be minimal. That would have been downstream of the diodes. Even if they were shorted when you were soldering the voltage, again, would be minimal. It should cause no damage.
Is it possible you had the meter on VDC instead of VAC? That will read a very low voltage regardless of the DC present. We did that last weekend checking out the newly built Paramours. A D'oh moment!
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You got a spark because your the the first cap in the supply was not connected to ground. The resistance check showed this. With the end of the cap not connected to ground, it held a charge until it had the ability to discharge it, which it did through the tip of your iron.
Looking at your build, I see a lot of untrimmed leads, which are a shorting hazard. I also see a lot of unnecessarily long leads, which also pose shorting risks. The general decisions to not follow the manual (non-stock wiring and parts, not orienting parts as shown) also make it hard to visually tell where there may be problems.
To answer your question, no the tubes not glowing is not a sign of dead rectifiers. The glow is from the heater supply (the twisted wires connecting the power transformer to the tubes); the rectifiers are in the high voltage supply.
Please post your voltages to determine the source of your problems.
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@Grainger
My multimeter was definitely on DC, but yeah that would've been embarrassing haha.
@fullheadofnothing
It's a messy build, but a lot of it is just for ease of parts removal later. I'm very confident the leads sticking out aren't an immediate issue. Sorry the non-stock parts add to the confusion.
I think I figured out why the heaters aren't working.
Each of the transformer's soldering tabs are wired to the transformer itself with some fairly thin wires that peek out from plastic molding. I think I severed the transformer terminal 5 wire when I was trying to remove a solder bridge. Crossing my fingers and hoping this is it. I'll post results/voltages when I get a chance in a few hours.
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Yeah it was that wire for the transformer terminal, the voltages checked out fine (all within 10%).
For the dc offset on startup, I peaked at around 11.3V. Is that too high?
1 88 (90)
2 171 (170)
3 0
4 171 (170)
5 85 (90)
6 0
7 109 (100)
8 0
9 107 (100)
10 0
11 0
12 0
13 170 (170)
14 0
15 192 (185)
20 0
21 212 (206)
A1 83 (90)
A2 0
A3 1.6 (1.5)
A4 0
A5 0
A6 86 (90)
A7 0
A8 1.6 (1.5)
A9 0
B1 86 (90)
B2 171 (170)
B3 108 (100)
B4 83 (90)
B5 171 (170)
B6 107 (100)
B7 0
B8 0
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Those numbers are fine, and the 11.3 is OK too. Do take some care in making sure the excess wires poking through terminals are trimmed short and that no leads from neighboring terminals are close to touching. This is an artform where neatness counts.
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Well I cleaned up the leads a little and listened to music for about 10 minutes. Went straight on to the speedball.
All the LEDs lit up fine except 1 LED on the smaller speedball board to the left (looking with the transformer further away from you). It was the LED closer to the 2N2907 transistor.
I tested voltages and every test point came up fine except terminal 20 which read ~70V instead of 0V expected.
I removed the LED to make sure of the orientation again, but it seemed it was right the first time. My DMM on continuity testing mode manages to make the HLMP-6000s light up with the probes across it, but I couldn't light up this one so it might be dead. Worst part is I sneezed and dropped it. Spent 20 minutes on my knees looking for it with no luck.
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If one of the LED's on one of the small boards doesn't light up, you will not have proper voltages.
Either terminal 1 or terminal 5 will not have the correct voltage.
I'd say 1 out of 1000 times, the LED is the issue, generally it is another cause that is indicated by whether the voltages at terminal 1/5 are excessively high, or 0.
If you have 70V at terminal 20, this is a separate issue that should have presented itself before installing the Speedball.
Terminal 20 is (eventually) wired to the chassis, which is where you have your black meter probe. So if you have 70V there, you have a bad ground connection somewhere.
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Either terminal 1 or terminal 5 will not have the correct voltage.
I'd say 1 out of 1000 times, the LED is the issue, generally it is another cause that is indicated by whether the voltages at terminal 1/5 are excessively high, or 0.
If you have 70V at terminal 20, this is a separate issue that should have presented itself before installing the Speedball.
Terminal 20 is (eventually) wired to the chassis, which is where you have your black meter probe. So if you have 70V there, you have a bad ground connection somewhere.
The weird thing is both terminal 1 and 5 tested fine (83V and 84V respectively with an expected of 90V). I'm beginning to suspect the LED was very faintly lit. It did seem to look slightly different with the amp completely powered off.
Also, very stupid mistake there. I meant terminal 19, not 20. Terminal 19 read abnormally with 70V instead of 0 expected. Terminal 20 read 212V with 206V expected, so that one is fine.
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The Bottlehead "favorite" LEDs are pretty good at producing 1.7V DC across them. If you get that when it is on they are good.
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I think you are reading one terminal off. Terminal 20 should be 0. Terminal 21 should be 206. 19 is not called out in the manual I have in front of me (you could have a different version- the voltage checks have changed). You also didn't call it out in the list of voltages you gave on the previous page.
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Oh man I really hope I wasn't just a terminal off, but my manual has 19 and 20 listed
I'm using the 12/17/2013 Crack manual and the 4/23/2013 Speedball manual. The voltages given on the previous page were what the Crack manual asked for. 19 isn't listed. However, 19 is listed in the speedball manual.
So here's the weird part:
Crack Manual lists:
20 0
21 206
Speedball:
19 0
20 206
I doubt it's a typo or else someone would've caught it by now. I don't know how the speedball kit would interact with those terminals to make things any different though.
I don't think I could really retest voltages now that I've gone and lost the LED. I won't be able to work on the crack until I'm back home from college again. I guess the project will have to sit on hiatus for 6 weeks. I hope you gentlemen will be just as helpful then. I'll get a replacement LED in the meantime.
**The 2012 version of the crack manual and the 2010 version of the speedball manuals are this way as well.
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Josh is the keeper of the manuals and the best bet is to go by what he says - 20 at 0 and 21 at 206. I can assure you that there is no statute of limitations around here on a typo being missed.
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Doc that's both great and terrible news.
I might've had a working speedball then. Now I won't know for 6 weeks! :'(
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Someone get me a gold star sticker for tenacity. I found the LED after sweeping the garage and sifting through the diust pile.
It is a typo in the manual then. The voltages checked out with 0 volts at terminal 20 and 213 volts at terminal 21. Music played through just fine!
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Consider the Gold Star issued!
Beautiful music, I bet.