Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: Blue on August 17, 2018, 06:25:40 AM
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Hi There,
After my Crack and Speed Ball has been working for 2 weeks, it has decided to exhibit some problems.
The left channel dies out after about 5 minutes of usage (you can hear it very barely). Before it dies, the left channel will have some loud static, then it pops and dies.
I resoldered all the joints on the tube sockets and the the OA transistor on the bigboard.
I tapped on all the solder joints, and no popping sounds come from it, so I think the solder joints on the terminals and sockets are good.
When the left channel dies out, the LED closest to the transistor at OA on the big board stops glowing.
I also measured the temperatures at some points.
The white ceramic resistors by the transformers are anywhere between 120-150 degrees Celsius when the left channel dies.
The transistor at OA on the bigboard is between 63-79 degrees., while the transistor at OB is at 47 degrees.
Once i let it cool off, and turn it on again, it works again for 5 minutes before the left channel fails again.
In those 5 minutes the voltages are correct.
One thing I noticed is when the left channel dies, the temperature sky rises on the mentioned resistors and transistor.
I took off the isolation sheet on the transistor and made sure that I put the vinyl tab on correctly, along with putting the isolation sheet back on.
Here are the voltages for the little board, big board and terminals.
Voltages not in range are listed in red.
Any help or advice is appreciated, thank you!
| Terminals | Big Board | Litte Board |
| 1: 75.4V | OA: 55V | OA: 75.4V |
| 2: 90.6V | OB: 76.6V | IA: 90.8 |
| 3: 0V | G: 0V | B-A/B: 0V |
| 4: 90.6V | B+: 92.5V | IB: 90.8V |
| 5: 54.8V | | OB: 55V |
| 6: 0V | | |
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Can you pull the 6080 and remeasure the small board?
It is incredibly likely that you do not have the TIP50 transistors properly isolated from the heatsinks. It's not just the insulating sheet that goes between the heatsink and TIP50, but also the shoulder washer that sits in the hole on the TIP50 metal tab and insulates the screw from the metal tab.
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I pulled the 6080 out and measured the little board. the Voltages for the board are as follows.
I am in Germany, so I have 230V mains. Ive also included a picture of the vinyl washer included with the kit.
It seems that part of it is not symmetric where it gets inserted into the transistor top. I have made sure I inserted it correctly, but Ill try it again and see what happens
| OA: | 74.5V |
| IA: | 240V |
| B-A/B: | 0V |
| IB: | 240V |
| OB: | 76.5V |
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If it's not properly inserted into the TIP50 it will deform like that and you'll have the issues you're having. I would recommend replacing it (and the other if it's deformed).
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If it's not properly inserted into the TIP50 it will deform like that and you'll have the issues you're having. I would recommend replacing it (and the other if it's deformed).
I am going to mark this as resolved. When i re-seated the washer, and angled the screw slightly more towards the side where the washer is not deformed, then the amp worked.
I've been using the amp now for a few hours now, and so far no problems. I;m going to order some new washers and replace the deformed one.
Thanks very much for your help, I appreciate it! The help and friendless here is amazingly good.
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"The help and friendless here is amazingly good."
That's true for sure. It's great.
Also, thanks for finding this issue and it's something that I will watch for when I get the courage to add the S.B. I like my amp so much as it is that I'm not very motivated yet.
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Okay, so I guess I closed the topic too early.
I'm still waiting for my new washers, but I replaced the metal screw and washers with a nylon screw and nylon nut.
After a few hours of use the same problem started happening again :/ So I am back to square one.
@fromnowon I think most of the people who bought the speed ball don't have a problem, and thus don't post about it.
I'm probably doing something wrong here, but I can't just figure it out. My next thought is that maybe the insulator tab (the clear plastic piece)
is deteriorating or faulty some how. However I'm no way certain.
Any other suggestions?
Thanks again for your help
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If the transistor isn't mounted properly, you'll get a resistance reading from the TIP50 metal tab to ground. Almost always this is a condition that happens immediately, not after a long time of running.
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I just ordered some new transistors and insulating tabs. Once they arrive, I'll completely replace the TIP50 for the left channel.
In the mean time, I'll double check all my other solder joints.
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If the amp is run long enough with this defect, potential damage can occur to the 6080 and/or the power transformer. It seems like your power transformer is still happy, but do consider that the 6080 might not be.
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I've replaced the TIP50 transistor at at OA, along with putting in a new nylon washer and new insulator tab on Tuesday, and have been running it daily since.
It has about maybe 20 hours of usage since the replacement, and everything seems to be working fine now.
I guess I can make this as resolved again. It's too bad I couldn't isolate the exact cause of this problem, but I'm guessing it was isolated to this area.
Due to the high temperatures caused by the transistors, my 270 ohm 5 watt resistors by the transformers looks pretty beat. Well, just the leads and not the resistors themselves.
I'd like to replace them anyway. However, I'm having trouble finding the exact kind and shape that is located in europe. Mouser seems to ship from the USA, which has a high shipping cost.
I did find a 270 ohm 5w resistor (10% tolerance) of a slightly smaller dimension, and I was wondering if this would still work?
Data sheet is here: http://www.produktinfo.conrad.com/datenblaetter/425000-449999/428052-da-01-en-HOCHLASTDRAHTWIDERSTAND_5W_270_OHM.pdf
And I uploaded a picture of it to show the difference
Thanks for your help again, really appreciate it
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If they fit, that's great! The tolerance is exceptionally unimportant there, provided the value doesn't creep up enough to increase dissipation.
The big challenge with the 270 ohm resistors in the Crack is that the one positioned between the two terminal strips needs to have sufficiently long leads to reach between the terminal strips, which your part does just fine.
The negative side of the parts that you've chosen is that the slightly longer body may not fit in the second position against the terminal strip. For that position, I would let the lead be a little longer on the tube socket side of the resistor.
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Thanks for the info Paul,
Well I guess I spoke again too soon! Last night the crack started acting up again.
This time the left channel doesn't die out, but rather every few minutes it makes kind of a white noise sound, or a noise like the wind is blowing (music is also playing).
It gets slightly louder, then it makes a pop sound in the left channel then continues working normally. Then a few minutes later the same situation repeats itself.
Increasing or decreasing the volume has no effect on the noise or pop, so I'm guessing the problem is after the potentiometer (and still probably related to the transistor).
I'm going to replace the 2N222A transistor while i replace the resistors, and maybe I'll reflow some components on the big board. If this doesn't work, Im going to put back
the 3k ohm resistors inside to see if maybe some other part is failing. I have 3 sets of output tubes, the standard 6080 (made sparks when I get it, so I don't use it), a second new old stoke 6080, and a 6H13C tube.
All exhibit the same problem.
I thought there maybe a cold joint somewhere, but poking and prodding all terminals produced no pops or audible changes
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So after a few weeks of no problems, the original problem started showing up again.
Left channel makes huge loud noise scratching noises. The LED closest to the TIP50 stops glowing.
I'm pretty at a loss as what is wrong. I'm not sure how possible it is to mess up soldering one piece so many times haha.
Although my big board visually has no signs of damage, I'm worried that further rework will eventually destroy the big board.
I'm going to take out the big board complete today and reinstall the two ceramic resistors, and then I will post some pictures of the big board from all angles. Maybe you can see something there that I can not. I just find it strange that the crack works for a few weeks at a time and dies.
There's one positive thing though. I'm definitely learning more about electronics along the way. Constant googling, trying to understand how all the components work. It's fun! Although sometimes frustrating :)
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I have reverted to the stock crack, but left the small board inside. The voltages in the crack manual are all within their ranges including tolerances.
I'll play with the crack for another week or two to see if something strange happens.
I have now uploaded some pictures of the big board. Maybe there is something wrong there that I am not seeing?
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I looked at my working Speedball in my crack and here is what mine looks like:
Its very different looking to mine??
Wondering if this is a later or newer version??
Alex
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We did do a minor revision to design out those jumpers and replace the front PC board.
Is the hardware nice and tight between your TIP50 transistors and the heatsinks?
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Yea the TIP50 is screwed nice and tight against the heatsink. Any tighter, I think I would start stripping the screw and or the nut.
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By the way, I can't help noticing that the soldering on your boards looks beautiful!
I wonder what kind of solder you used . . .
I'm sure that you will get this sorted out!
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Thanks for the compliment, but my soldering skills are still quiet amateur haha.
I use a standard 60/40 rosin core solder.
I bought this one on ebay: https://www.ebay.de/itm/321315268878
I work as a software engineer at an automotive firm, and we have a hardware department, so I have good access to a ERSA RDS80 soldering station with all sorts of iron tips. It makes soldering easy from tiny SMDs to point to point. My boss encourages everyone to use the work stuff after hours for their own personal projects.
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So far it has been 10 days using the stock crack with the small board. No problems so far.
I'd like to attempt to reinstall the big board in the crack.
I haven't done any soldering rework on the big board yet. Any suggestions on what I should do before I put it back in?
I'm tempted to resolder all the components for the left channel on the big board, however I am waiting on a new set of LEDs before I do that (I read that one shouldn't reflow the LEDs due a high possibility of them cracking on a reflow).
How tight does the transistor need to be against the heat-sink? I can't tighten it anymore that I originally had it.
However, for the right channel, all i used was a flimsy screw driver and a pair of pliers, and yet the right channel has non of the problems I have in this thread.
Could this problem occur from any other places? Perhaps poor solder join somewhere else?
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It might not be a bad idea to replace the TIP50 and 2N2222 where you originally had the mounting insulation issue (A side).
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I did replace both the TIP50 and 2N2222 once already. When I replaced the two, the crack worked without problem for two weeks.
Once the problem occurred again, it would fail after 5 minutes of operation like originally. I have another 2N2222 and a few TIP50s remaining.
Once the LEDs come in, I'll replace all of them at once.
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It would also help to know what voltages change once the board stops working.
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So I decided to try just replacing the 2N resistor and TIP50 in the meantime.
Before I removed the 3kohm ceramic resistors, I did a full resistance and voltage check, all good.
Now I attempted to put back the big board. This time the B+ voltage on the bigboard fails. It falls to 112 volts. I only quickly checked OA/OB (they were about 79 volts), but stopped measuring because I started to feel an intense amount of heat coming from the Crack. I didn't want to destroy any other components Did I destroy my big board? I wouldn't be surprised as I have reworked it many times now.
Therefore I put back the 3kohm resistors and left the small board in. I did a full resistance and voltage check, and everything seems to fit, other than T2 and T4 being a bit higher than the tolerances., but I am guessing that is due to the small board
Here are my voltage checks with stock crack and small board:
T1: 80.8
T2: 197
T3: 0
T4: 197.2
T5: 83.9
T6: 0
T7: 111.1
T8: 0
T9: 117
T10: 0V
Small board:
OA: 80.5
IA: 196.6
B-A/B: 0
IB: 197
OB: 83.8
Should I just give up on the big board and order a new one? I'm afraid that eventually I'll destroy my transformer.
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If the B+ voltage drops like that, the TIP50 transistors are not properly insulated from the heatsinks.
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I’ll get back to it again on the weekend.
As for mounting the tip 50, it goes screw, Fiber washer on top with protruding end facing towards the insertion side, transistor, thermal insulator tab, heat sink, metal washer, lock washer, nut.
I’m sure my picture shows that too. I find it perplexing that isolating the transistor is so complicated .
I’ll take a picture of each step of mounting the transistor against the heat sink.
I’m also tempted to try one of your tests in an older thread: pulling back the transistor from the mounting kit, and measuring the voltages then, running the amp for no longer than 30 seconds
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I would think that you could check continuity or resistance between the heat sink and metal tap on the transistor to verify proper installation. Correct?
If the shoulder on the fiber washer did not seat properly it could result in a short between the transistor and heat sink even if order and orientation of all parts are correct.
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This might help.
It's essential that the screw with fiber washer are centered in the transistor.
https://www.youtube.com/watch?v=UWNVMkNwkUw
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Yea I followed the exact same video when I originally built the speedball, and probably watched it another 10 times trying to solve this problem.
I also checked for contact between the transistor metal tab and the heat sink.
My Multimeter was not beeping. The transistor is currently disassembled from the heat sink. I’ll be trying it again on the weekend.
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So I pulled both TIP50 transistors away from their heat sinks to measure the voltages, the amp was on for no longer than 25 seconds.
B+: Starts at 185 volts, and then drops to 112 volts after a few seconds just like before.
What should I check for next?
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Honestly I would just replace the big PC board. There's only so much debugging and rework that you can do on one of those PC boards before they are destroyed, and my guess is that you're getting close.
If the B+ drops like that with the TIP50 transistors not touching the heatsink, then you almost certainly have a shorted transistor on there.
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Yea, I’m going going to order an entire new big board.
I’ve already replaced the offending transistors twice, and I see no visible bridges between the transistor legs. I am not the best at soldering, but I really don’t see any bad joints.
Last week I checked for shorts in the transistors with my multimeter, but it showed it was fine.
Perhaps reinstalling the big board today caused a short.
However I’m not interested in damaging the rest of the components, and I’m slowly going crazy checking the same things over and over. I need to email [email protected] correct?
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Yes.
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I just did a repair of a different kit, but with similar style of upgrade PC bards. The issue with that kit was that lots of the wires connecting the board to the circuit below had been nicked by the wire strippers used and the wire had fractured just inside the insulation where it wasn't visible. lt's worth checking the connecting wires themselves for continuity.
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Thanks for your reply Doc.
I went ahead and checked for continuity in the wires, they seemed fine. However, I replaced the all the wires on the speeball big board anyway.
Still have the same problem.
I decided to check the 2N2222 Transistor and the LEDs on the board. The top side of the big board were measuring properly.
The bottom side measured wrong though. The TIP50 measured correctly on the bottom side of the big board as before, but the
2N2222 transistor was measuring 1.025 volts from Emitter to Base when it should show over limit. Also the the LED closest to the TIP50 transistor was not showing any reading at all.
It's the third time I had to replace the 2N2222 for similar reasons. However this is the first time that the LED failed to measure.
I'm still waiting on my delivery for the LEDs. If installing all new LEDs and transistors for the left channel don't work, I am going to purchase a new big board, as Paul said, it's probably better to do just that.
Thanks for your help everyone.