Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: arif on September 15, 2014, 09:50:55 AM
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Hello, first time trying DIY electronics. Tried my best to go through the steps to assemble Crack as specified in manual. After assembly, the resistance readings looked good. These are the reading before installing the tubes:
1 - 140 K ohm and going upwards
2 - 115 K ohm and going upwards
3 - 0 K ohm
4 - 97 K ohm and going upwards
5 - 115 K ohm and going upwards
6 - 2.4 K ohm
7 - 2.9 K ohm
8 - 0 K ohm
9 - 2.9
10 - 2.4
12 - 0 K ohm
13 - 270 K
14 - 0 K ohm
20 - 0 K ohm
22 - 0 K ohm
B3 - 2.9 K ohm
B6 - 2.9 K ohm
Groung lug - 0 K ohm
Black Pin 90 K ohm
Red pin 103 K ohm
After that, installed the tunes and and put the fuse on. Then powered up. The smaller tube was glowing (with both lights glowing below the smaller tube). Not sure if the bigger tube is supposed to glow too. Unfortunately the voltage reading were mostly off. For example I got about 215 V on terminal 1. And there were lot of 215 v reading in some other terminals too. Then after a while the fuse went out. No smoke or burning smell though. Please advice.
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Put another fuse in and do your best to measure the voltages.
215V on terminal 1 is going to be what you'll get for the first 10-30 seconds until the tube warms up.
If the fuse blows that slowly, it could be a backwards cap somewhere in the circuit.
-PB
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Thanks for the reply! I will try to measure voltage after putting a new fuse and post the results here.
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Hello, after installing a new fuse and waiting about 2 min after the power was turned on, the voltage reading looks as following:
1. 208 (75-90)
2. 208 (170)
3. 0
4. 208 (170)
5. 89.7
6. 0
7. 0 (100)
8. 0
9. 0 (100)
10. 0
11. 0
12. 0
13. 207.7 (170)
14. 0
15. 215 (185)
20. 0
21. 222 (206)
A1. 90
A2. 0
A3. 1.56 (0)
A4. 0
A5. 0
A6. 207 (90)
A7. 0
A9. 0
B1. 206 (90)
B2. 207 (170)
B3. 0 (100)
B4. 89.3
B5. 207.5 (170)
B6. 0 (100)
B7. 0
B8. 0
Any advice will be appreciated.
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I will provide advice assuming there is no Speedball in the Crack.
1. Are both tubes glowing? Is the keyway in the 8 pin socket facing the front of the chassis?
2. A3 doesn't have a voltage listed in the manual because it's very easy to do damage to the amplifier probing around in there. Your A3 voltage, however, is correct.
3. Are both halves (side-to-side) of the 12AU7 glowing? It looks like you have one half conducting, but the other half is not.
-PB
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The keyway in the 8 pin socket was not facing the front of the chassis, after fixing/rewiring everything is working fine. Installed the Speedball as well after that. Loving it!
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After putting the crack and Speedball together, the voltage check looked fine. The amp sounds great too. One issue is that the fuse is blowing every couple days. I already put like 5 fuses during last week. Any idea what is going on?
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What kind of fuse are you putting in?
If the voltages measured acceptably, the fuse shouldn't pop.
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I am using this fuse:
https://www.sourceresearch.com/Store1/quickstore.cfm?ProductID=215080&do=detail
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Try a 1A-2A fuse.
-PB