Smoking Crack untill the Fillaments Glow

[Crackhead]

Hi everyone, embarrassingly I am on about my 3rd round of trying to get my Bottlehead crack working with the speedball upgrade.  It worked fine before without the constant current source but I botched the speedball the first time around by lifting a trace on the big board.  I have since gotten a replacement and installed it.  After installing a new speed ball properly my 5 watt resistor smoked and the ceramic housing disintegrated.  Also I am only getting about 13 Volts from Terminal 1 and about 40 from terminal 2

The worst part is that I am an aspiring electrical engineering student (still in Community College) and all of this seems like a bad omen for my career... J/K...

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fs21.postimg.org%2Fdrchu0vs7%2FIMG_3548.jpg&hash=0451185bea31160360c9ea3f4103d68936a1be70)
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fs21.postimg.org%2F51k06x3on%2FIMG_3550.jpg&hash=342140a9ccdaf42a463e01b567407cf1db1a992c)

Thanks in advance for any help you may be able to proffer...

[JamieMcC]

I suggest not powering up the amp again until you have some instruction from the Bottlehead team.  If you could post some more pictures of  the hooking up transformer tube sockets rectifiers etc that's going to be helpful.

[Paul Birkeland]

Did you install the TIP50 transistors properly? (with all the specified hardware in all the specified places?)

[Rocketman248]

After installing a new speed ball properly my 5 watt resistor smoked and the ceramic housing disintegrated.  Also I am only getting about 13 Volts from Terminal 1 and about 40 from terminal 2

I'm sorry, but I would imagine that it was not installed properly.  Please re-read the last note on Page 42 of the manual.  "If you see smoke, SHUT IT OFF!!!"

Post some pictures of the Speedball installation.  The forum will get you sorted in no time. 

[Crackhead]

Thank you all for your near immediate responses.  I will re-recheck my speedball install as the gentleman from Japan suggests and post pictures if the solution still eludes me...

Thank you wonderful men again.

[Nathan]

Please double and triple check your work. I have a perfectly working crack with speedball. Aside from a bad solder joint in my initial build, the only time I ever had an issue is when I did a mod and mis-wired one lead. My point is if the instructions are followed precisely, your crack will work well, baring a defective component.

BTW it took me a while to recognize that one wire was not properly connected

[Crackhead]

I am still unable to resolve my issue... Perhaps pictures of my Speedball install will assist you to assist me?

Thank you for your time in advance.

[Nathan]

Pictures always help

[Rocketman248]

Trim those TIP50 leads.  They might be shorting on something.  Same goes for the 2N222A leads.  Anything sticking out more than 1/8" or so, give it a trim.  Be careful to remove all loose clippings too.

[Paul Birkeland]

Try running the amp with no 6080 installed and let us know what the voltages are on terminals 1-5.

-PB

[Crackhead]

I ran the amp without the 6080 tube and recorded the readings:

Terminal # 1 - 81.5 bolts
Terminal # 2 - Erratic Readings
Terminal # 3 - 0
Terminal # 4 - 0
Terminal # 5 - 80 bolts

Also, thank you man from Japan but it appears there are no shorts here to report...

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fs9.postimg.org%2F6ex1z96e7%2FIMG_3590.jpg&hash=29f69cf7183a45c9184725c33ad703223892c4ae)

[Paul Birkeland]

I ran the amp without the 6080 tube and recorded the readings:
Terminal # 1 - 81.5 bolts
Terminal # 2 - Erratic Readings
Terminal # 3 - 0
Terminal # 4 - 0
Terminal # 5 - 80 bolts

You can't have ~80V at 1 and 5 without having more voltage at 2 and 4.  It's possible that you need to go up one scale on your meter to see what's there.

This basically confirms an issue with the large board feeding the 6080.  Nearly every time we see this, it's because the hardware used to mount the TIP50 has not been installed properly, and the metal tab of the TIP50 is touching the heatsink through the mounting screw.

-PB

[richmi]

Perhaps you can check that you have the right part attached to the heatsink.

The part number that shows partly on your picture reads MJE57...

I enlarged a detail of one of your photos. Maybe it is not the TIP-50 transistor you are supposed to have there.

Richard

[mcandmar]

Now that's impressive, how on earth did you spot that!

[Doc B.]

Well done, Rich. This is a classic example of why we suggest builders who are having problems have someone else look over their work. That person doesn't even necessarily need to electronics knowledge though, as shown here, experienced eyes here can often spot things quickly. A fresh pair of eyes will often spot a discrepancy that we as builders can look at again and again without seeing.