Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: zlib on September 26, 2015, 11:49:27 PM
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3 years ago I was a happy owner of Crack but one day left channel stopped working, then the other. I didn't solve the problem and left Crack for better times...
Some weeks ago I decided to revive my Crack but I found a lot of rust on RCA jacks and screws (ambient conditions were not very good). I changed RCA jacks, volume pot (Alps 100K) and headphones jack. Also I changed two large ceramic resistors (3K 10W) for another pair (3K9, 10W) and changed some wires to Oyaide 18 AWG. So, I disassembled my Crack and rebuilt it from scratch.
In previous topic we solved the resistance check problem: http://bottlehead.com/smf/index.php?topic=8417.0 Now I have another problem. When I turn it on the tubes are not glowing.
I checked power entry socket and power switch - they show signal from one side to another. The capacitors show some signs of life too (the values on my meter gradually change). So, where the problem might be? Is it power supply, bad tubes or something else? Is it safe to do a voltage check if the tubes don't glow?
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Is it safe to check voltages if the tubes don't glow?
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Start with the resistance test. If you pass that then move on to the voltage test.
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Since your first issue was resolved by resoldering a questionable connection I would suggest reflowing your solder joints with a hot iron one more time to make sure they are all conducting. Run the resistance check again, and then check voltages.
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Also I changed two large ceramic resistors (3K 10W) for another pair (3K9, 10W)
That's not a suitable replacement.
A voltage check will help locate the problem.
(The aftermarket headphone jack and volume pot with pins in conjunction with stranded wire will render your Crack very difficult to repair in the future)
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Here are my voltages. Please, be aware that I live in 230V country.
Terminal - voltage
1 - 220
2 - 240
3 - 0
4 - 240
5 - 220
6 - 0
7 - 0
8 - 0
9 - 0
10 - 0
11 - 0
12 - 0
13 - 230
14 - 0
15 - 240
20 - 0
21 - 240
A1 - 230
A2 - 0
A3 - 0
A4 - 0
A5 - 0
A6 - 230
A7 - 0
A8 - 0
A9 - 0
B1 - 230
B2 - 240
B3 - 0
B4 - 230
B5 - 240
B6 - 0
B7 - 0
B8 - 0
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Looks like everybody are too busy to help me further (or my problem is too difficult)... Meanwhile I found bad joint at terminal 12 and resoldered it. Also one of the LEDs (from center to A8) looks dead (my meter doesn't show anything in either direction). Is this LED the source of my problem or is it just a result?
And some update on resistance check. I have 3.8K on terminals 7, 9, B3, B6 (because my big resistors are 3K9 10W, I guess). Is it fatal or not?
Also the resistance on terminal 13 doesn't change slowly like the manual says, it changes chaotically in both directions. Is it normal?
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Once you make a change like fixing the bad solder joint at 12 it is time to remeasure your voltages and post any terminal voltages that are not to spec, as they have probably changed.
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I remeasured voltages but they are the same as I posted earlier.
As you can see, I have nothing on terminals 7, 9, A3, A8, B3, B6 (but there must be something as manual says). The resistance check is OK now (with the exception of 3.8 KOhms on terminals 7, 9, B3, B6 instead of 2.9 KOhms - because of different resistors). And the LED from center A-pin to A8 looks dead (is it the source of all problems or is it just a result?)
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What is the AC voltage between power transformer terminals 4 and 5? That is the origin of the voltage that causes the tubes to glow. Without tubes glowing, you will have the symptoms you describe.
-PB
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Meter shows something about 5.8 V between power transformer terminals 4 and 5.
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Now measure AC voltage between B7 and B8.
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Between B7 and B8 I have 0.
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Ok, well, one of the two wires going from power transformer terminals 4 and 5 isn't making contact over there. This can be a soldering issue or a broken wire.
-PB
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Ok, well, one of the two wires going from power transformer terminals 4 and 5 isn't making contact over there. This can be a soldering issue or a broken wire.
Thanks! That was the case! I attached the wire from power terminals 4 and 5 to B7 and B8 but didn't solder them at B7 and B8. Now the big tube glows but the little one doesn't. Only one LED glows and the other (at A8) doesn't.
Now the voltages at mentioned terminals are:
7 - 150
9 - 100
A3 - 0 (but the LED glows here!)
A8 - 80 (the LED doesn't glow here!)
B3 - 150
B6 - 100
The difference between 7 and 9, B3 and B6 may be because of the dead LED at A8? So, I just need to replace it and everything will work OK, right? Or do you see another problem in my voltages?
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Can you carefully measure the voltage at A7? 80V at A8 has several causes, but is something we can deal with fairly easily.
One glowing LED on the socket means that at least half of the tube is glowing. This can happen if the wire connecting to A4 and A5 is only making a good connection to one of those pins.
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It's very hard to see but yes, I see now how the half of little tube glows. So, the second LED is definetely dead. But my voltages show different values now. Or maybe it is because of different meter?.. Anyway, here are all voltages (the values are rough because I use analog meter):
1 - 150 (!)
2 - 160
3 - 0
4 - 160
5 - 80 (!)
6 - 0
7 - 150 (!)
8 - 0
9 - 100 (!)
10 - 0
11 - 0
12 - 0
13 - 160
14 - 0
15 - 190
20 - 0
21 - 210
A1 - 80
A2 - 0
A3 - 1.5
A4 - 0
A5 - 0
A6 - 150 (!)
A7 - 0
A8 - 0 (!)
A9 - 0
B1 - 150 (!)
B2 - 170
B3 - 150 (!)
B4 - 80
B5 - 170
B6 - 100
B7 - 0
B8 - 0
I marked the suspicious values with "(!)" mark. I don't know which value must be different because of 230 V country (manual provides values for 120 V country). But looks like I must have equal values at terminals 1 and 5, 7 and 9, A1 and A6. Maybe they are different because of one dead LED? Also, I have 0 V at terminal A8 (because of dead LED, I guess) and suspiciously high values at B1 and B3.
So, I ordered new LEDs. Will it solve all suspicious voltages or not?
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The voltages are consistent with half the 12AU7 not glowing, as PB said. If the tube cathode is not heated (glowing) then no current can go through the LED. There is no evidence yet that there is anything wrong with the LED itself. Again, as PB said, look at A4 and A5; one of them is probably a bad solder joint.
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There is no evidence yet that there is anything wrong with the LED itself. Again, as PB said, look at A4 and A5; one of them is probably a bad solder joint.
I measured the resistance between LED legs. The one at A3 shows something and the one at A8 doesn't (of course, I tried both directions). Doesn't it mean it is dead?
A4 and A5 looks fine for me. I have 0 Ohms between power transformer terminal 4 and A4/A5. It means they have good joints, I guess.
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Can you see both halves of the 12AU7 glowing?
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Pull the 12AU7. Measure the resistance of the tube pins 4 to 9 and 5 to 9. If they both read low resistance, measure the voltage at the actual tube pins - not the solder joint - from 4 to 9 and 5 to 9 with the 12AU7 inserted.
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I measured the resistance between LED legs. The one at A3 shows something and the one at A8 doesn't (of course, I tried both directions). Doesn't it mean it is dead?...
Ah, I found it (post #7 of 23) - that's what I get for jumping into the middle! I probably thought you had measured voltage, not resistance. Yes, it's probably dead. It would be nice to know how it died, in hopes that the replacement does not die immediately. Is it perhaps in backwards? Anyhow, the team is making progress. Pay attention to PB; he designed the amp and has fixed hundreds of them!
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I measured the resistance between LED legs. The one at A3 shows something and the one at A8 doesn't (of course, I tried both directions). Doesn't it mean it is dead?
Potentially. You can jumper A3 to A8, then check the voltages at terminals 1 and 5 again.
-PB
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Pull the 12AU7. Measure the resistance of the tube pins 4 to 9 and 5 to 9. If they both read low resistance, measure the voltage at the actual tube pins - not the solder joint - from 4 to 9 and 5 to 9 with the 12AU7 inserted.
I have low resistance from 4 to 9 (actually, it changes... is it OK?) and I have nothing from 5 to 9. Does it mean the half of tube is dead?
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In a 12AU7 dual triode the heater has one end connected at pin 4. The middle is connected at pin 9. The other end is connected at pin 5. The section from 4 to 9 heats one triode's cathode and the section from 5 to 9 heats the other triode's cathode. Each half of the heater is connected to power in parallel, so if one is out the other will still heat. Thus if you have an open reading from 5 to 9 it would imply that that half of the heater is open. Be sure that it's not just oxidized tube pins, that can create a false open reading.
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When I turn Crack on I see only half of this tube glowing, so if it is oxidized tube pins then they influence the work of the tube too. So, should I change this tube or not?
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If it's oxidized tubes pins you could try cleaning them. If the heater is open the tube will need to be replaced.
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I tried cleaning the pins but still I have no resistance from 5 to 9. So, I will wait for new 12AU7 and LEDs, then we will continue.
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I tried cleaning the pins but still I have no resistance from 5 to 9. So, I will wait for new 12AU7 and LEDs, then we will continue.
Change the tube first. If half the tube doesn't conduct, one LED will not light.
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I have received new LEDs and 12AU7 tube and now my Crack works and sounds very well. Thanks everyone! But I also have an assembled speedball kit and I want to integrate it in Crack. Will you help me again?
Two years ago speedball upgrade made my Crack smoking. Maybe it was because of bad main Crack kit assembly (I removed speedball and reverted back to just Crack, but my Crack stopped sounding in a year), but maybe there was a mistake in speedball assembly too... Now I recheck every step from manual and one thing took my attention. There are two 2N2222A transistors on large board and manual advises to leave some space between the metal body of the transistor and the PC board. One of those transistors is soldered without leaving the space between transistor body and the board. Is it critical or not?
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A Crack that smokes after Speedball installation is due to improper mounting of the TIP50 transistors.
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Actually the power supply started smoking back then. Is it TIP50 transistors anyway?
What about 2N2222A's body touching the PC board? Is it OK?
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Actually the power supply started smoking back then. Is it TIP50 transistors anyway?
A smoking power supply in a Crack after Speedball installation indicates an improperly mounted TIP50 transistor.
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I checked speedball boards (double checked TIP50 transistors!), resoldered suspicious joints and then I installed speedball into my Crack. And here are my voltages:
1 - 80
2 - 150
3 - 0
4 - 150
5 - 80
6 - 0
7 - 100
8 - 0
9 - 100
10 - 80 (!)
11 - 0
12 - 0
13 - 50 (!)
14 - 0
15 - 100 (!)
19 - 60 (!)
20 - 0 (!)
A1 - 3
A2 - 0
A3 - 0.5
A4 - 0
A5 - 0
A6 - 40
A7 - 0
A8 - 1.5
A9 - ? (can't reach it now)
B1 - 35
B2 - 40
B3 - 30
B4 - 25
B5 - 45
B6 - 0 (!)
B7 - 0
B8 - 0
So, the voltages at terminals A1-9 and B1-8 are in total mess. And terminals 10, 13, 15, 19, 20 look bad too. Where should I search for a problem?
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You really didn't need to measure the voltages at A1-A9. The voltages at terminals 1 and 5 tell enough of the story to not need that.
For instance, seeing 80V at 1 and 80V at 5 tells me that your voltage measurements at A1 and A6 aren't possible, and that you have 1.5V at A3 and A8. This is why we don't have these voltage checks in the Speedball manual.
The voltage at 10 is very distressing, and the amplifier shouldn't be plugged in unless that is remedied. Can you double check that terminal? Is there any debris or component leads from 9 to 10 that might create a short circuit?
Are both the 2.49K resistors on the headphone jack still properly installed? Do they both look to be about the same color?
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The voltage at 10 is very distressing, and the amplifier shouldn't be plugged in unless that is remedied. Can you double check that terminal? Is there any debris or component leads from 9 to 10 that might create a short circuit?
Are both the 2.49K resistors on the headphone jack still properly installed? Do they both look to be about the same color?
I found a problem: the wire from headphone jack to terminal 10 fell out from terminal 10 after bending caps near octal socket. So, I resoldered it and now terminal 10 shows 0. But all other terminals have the same voltages as before. Still have 0 at terminals 20 and B6, for example.
You really didn't need to measure the voltages at A1-A9. The voltages at terminals 1 and 5 tell enough of the story to not need that.
For instance, seeing 80V at 1 and 80V at 5 tells me that your voltage measurements at A1 and A6 aren't possible, and that you have 1.5V at A3 and A8. This is why we don't have these voltage checks in the Speedball manual.
What if some wires were broken during the installation of speedball boards? Actually, my manual from 2013 have these voltages and they are very different from mine.
Some observations during the voltage check:
1. LED from center A to A8 glows but the LED from center to A3 does not. I checked the contact from A3 to center A - it is OK, my meter shows some resistance.
2. All other LEDs on speedball boards doesn't glow. But during the previous voltage check I saw them glowing. Do I have glitches in my eyes?
3. Both tubes glows normally.
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1. LED from center A to A8 glows but the LED from center to A3 does not. I checked the contact from A3 to center A - it is OK, my meter shows some resistance.
This will result in a voltage discrepancy at either T1 or T5.
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T1 means terminal 1? The voltages at terminals 1 and 5 seem fine to me. Where should I search for a problem now?
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B6 and terminal 9 are connected with a solid piece of wire. If you have 100V at terminal 9, you have 100V at terminal B6.
I would recheck your voltages, but just terminals 1 through 10.
-PB
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I noticed two bended capacitors' bodies touching the terminals. Now I moved them a little and here are my new voltages:
1 - 45
2 - 50
3 - 0
4 - 50
5 - 0!
6 - 0
7 - 40
8 - 0
9 - 0!
10 - 0
So, what should I check now?
Oh, and now one of those capacitors' bodies touches one lug of heat sinks (where TIP50 transistors are installed). Is it bad?
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If voltages changed because you moved some parts the chances are good that the solder joints on those parts are not working 100% and need to be reflowed.
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Oh, and now one of those capacitors' bodies touches one lug of heat sinks (where TIP50 transistors are installed). Is it bad?
Yeah, that could present a problem down the road if the wrapping on the cap becomes damaged.
Your voltages are now varying wildly, and you seem to have a bit of a short now.
Can you post some photos of your build?
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I moved the capacitor's body a little away from that lug but the voltages didn't change. Here are more precise voltages (done with digital meter):
1 - 38
2 - 43
3 - 0
4 - 42
5 - 2.3
6 - 0
7 and B3 - 34
8 - 0
9 and B6 - 0.1
10 - 0
Photos are in attachments.
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It looks from the photos like potentially our TIP50 transistors are not mounted properly.
Please go back and carefully consult the manual, verify the steps, and check to see that your hardware is where it should be.
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What exactly is wrong with TIP50? I have inspected them 4 times already and can't see anything different from the manual.
I have mentioned before the only potential problem I see: I didn't leave the space from one 2N2222A transistor's body to PC board (see the attachment). Is it really a problem?
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The lockwasher should be between the flat washer and the nut. They are not there.
In the first picture, zoomed in over the the transistor, there is an extra lump visible between the screw head and the transistor tab.
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From the top-down shot that you posted, it looks like there are washers that aren't where they are supposed to be.
Go back to the first photo on page 15 of the Speedball manual, then look at your boards just to be sure.
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Wow, looks like that's it! I tried to measure the voltages without the screw, nut and washers on heatsinks and the voltages look nearly perfect! All LEDs on boards are glowing too. I will try to move fiber washer from nut side to screw head side.
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I tightened the screws on heat sinks but after about a minute the LEDs turned off and my voltages returned to previous low values everywhere. About that fiberwasher... It is not actually a fiber, it is a platic one but it doesn't conduct the current, right? I don't remember now if I had fiber washers in speedball kit or not but those plastic ones are the ones I have now anyway. Is it a problem?
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The plastic washers are insulators. If they aren't in properly, they can't insulate.
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I rolled up the screws with cotton thread and now my meter shows nothing between the screw and middle leg of TIP-50 transistor. The voltages seem OK too, all LEDs are glowing (but the LEDs on small PC boards are glowing less than the others).
Now I have the noise in left channel. The noise changes in time... When I turn the amp on I hear loud noise in left channel, after about 10-15 seconds it sounds way more quiet (some people don't notice it at all at this stage) and then it produces BOOMs occasionally. The noise is not related to the volume level. Once again the only potential problem I see is that 2N2222A transistor which was soldered without leaving the space between transistor body and PC board. I tried another 12AU7 but the noise is still present. Could you help me, please?
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Hi,
Your solder joints look rather matte and convex; they should be shiny and concave. Perhaps you are not applying enough heat when soldering. This can create cold joints and cause the noise you are hearing in one channel. Make sure that your iron touches all the parts to be soldered and when the lead is melted, count to three and remove your iron.
Richard
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I agree, cold joints will cause that kind of noise.
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OK, I resoldered almost every joint and made some space between PC board and 2N2222A transistor's body. Now my Crack sounds very good, but during the first 30 seconds after turning on there are some noisy cracks in left channel, after that everything is normal. I measured the voltages and found the difference in voltages between terminals 7 and 9:
7 - 108
9 - 98
Is it still cold joints or something else? In the past when I had problems with left channel the terminal 9 voltage was around 118.
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7 - 108
9 - 98
Is it still cold joints or something else? In the past when I had problems with left channel the terminal 9 voltage was around 118.
The voltage at 9 dropping by 20V suggests that you have fixed a flaky solder joint.
If you still have noise, there are likely still other cold joints.
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I rolled up the screws with cotton thread and now my meter shows nothing between the screw and middle leg of TIP-50 transistor. The voltages seem OK too, all LEDs are glowing (but the LEDs on small PC boards are glowing less than the others).
I would shoot an email to Bottlehead's replacement parts department and get the proper transistor mounting kit. The thread may work for now, but that seems pretty sketchy to me.