You know that you are having a bad day when.......

[wrenchone]

Good deal that you could rescue victory from the jaws of defeat. So often, Murphy prevails, and it's the other way 'round.

[Tekko]

I was mounting transformers in a box for the 833 project, i needed a hole in the base plate of the transformer, so i brought out the drill and started drilling very carefully to make sure i wouldent jam the bit into the primary, what happens ?

I jam the stupid bit right into the primary of the main power transformer, during a first visual inspecion i feared the worst so i had to test it to make sure it really was dead, it was a big relief hearing the startup hum, turns out i reacted fast enuf and only scratched the surface of the wire.

In the end the transformer ended up in a different location and needed yet another hole in the base plate, luckily this time the hole got drilled without any damage.

Anuther flunky was when drilling the mounting holes for another transformer, mistaking a scratch for an actual drill mark*DOH*

[tubelab.com]

So often, Murphy prevails

Well I finished the car so I resumed where I left off. I had previously twisted my power supply as far as it would go to see how much drive voltage this thing could put out. The power supply goes to 550 volts. While working on the car I was thinking 550V? The 10M45 is only rated for 450 V why didn't it blow? When I resumed I was scoping the 10M45 and I discovered that it was indeed seeing about 500 volts. It was also starting to smoke! Power OFF! Well the 10M45 will indeed handle 500 volts, It really does not like to dissipate nearly 5 watts without a heat sink. Heat sink added. Heat sink is elevated to 550 volts. Note to self. Don't touch it. While doing some further testing I started to smell a smell that only an electrolytic cap can make. Note to self, 400 Volt caps really don't like 550 volts. I took it out. Board works fine without it. It ran for 1/2 hour at 550 volts.

I have decided to cease playing with this dangerous toy. I have tempted Murphy twice already and I don't want to have him visit me today. I want to add the PowerDrive circuit so that I can make something glow. This means moving the CCS's to the other side of the board. If I get done tonight I will "test" some tubes. I don't know which ones yet.

[wrenchone]

You were really tempting the old gentleman. You must have an angel hovering over your head these days... Murphy has visited me at times in the past few weeks - usually his malice is confined to shocks from charged caps or fractured surface mount caps that are impossible to diagnose (shotgun the lot and pray). I have my own driver that I'll be testing in the next couple of months, as soon as I get some musical and job obligations out of the way. Our goals are the same - drive the heck out of some screens and have some juice left over for NFB.

[GK]

You can still use the boards - just solder the components on the copper side. Here is one I screwed up - The unloaded board on the right has the copper on the correct side!

EDIT: Oops. Should have read past the first three posts before posting this.

[tubelab.com]

Yes< this little project started out on shakey ground, stumbled a few times, but grew up big and strong. I moved some more parts from one side of the board to the other, and added the mosfets. I installed some absolutely monstrous heat sinks because they happened to already have tapped holes in the right places.

I plan to use this WMD to find the limits of screen drive, but first I intend to answer a question that I have wondered about since I was about 15, but only now have the ability to really answer. The question? Just how many watts can a pair of 6L6GC's put out without melting?

I have made guitar amps since I was 14. Most of my early ones used old TV parts, but somewhere in High School I graduated to 6L6GC's. My best amps strained to make 60 watts. I know that a major weak point is the propensity for an arc to occur between pin 3 (plate) and pin 2 (heater). This limits the plate voltage, so I plan to explore the possible power gains to be had by using AB2.

I will report on these activities in the 6L6GC AB2 Amp thread and the Screen Drive Push Pull ideas thread.

[wrenchone]

Another possibility is to use the super 6BG6GAs with the plate cap. SY says they laugh at high voltage - I intend to test that myself...

[Sal Brisindi]

I built my first point to point hand wired 6 digit nixie clock a few years back using 12 TTL IC chips.

I laid out the sockets and soldered wire after wire. I was half way through and I noticed with the clock right side up time was SS:MM:HH instead of HH:MM:SS... duh!

Sal

[richwalters]

Bad days, these are getting ever more common. Recently I purchased some USB digi scope software and after loading the stuff in my laptop; later found this "new thingy" didn't work and repeatedly crashes into desktop. One goes through the reload and download updates. Claimed for XP working I gotton on to the manu and after a downtime bank holiday they were aloss to find a solution. What really annoys me, is the time I spend degugging someone elses flawed b-astard software to find no comments have been added behind software routines. Such glossy product writeup's and performance prowesses but beware of such flawed software and crappy customer service. Again reorganising return of goods and cash back is another irritating lark some of us experience. At least the replacement of duff tubes is largely quibble free.
My black cat persuaded me to find the problem. It was simple. The product uses 5V USB port. I discovered the juice dropped to 4V when certain digiscope functions were started. So I spliced another cable to the 5V and it now works. Why the hell do manufacturers design equipment on the borderline 0.5A current from a USB port ? This is an accepted standard. What is the next shortsightedness.

richy

[ke4mcl]

take board and toss it in closet or other place out of sight. leave it alone. come back later.