HP 120B updateMy old Safrane has LPG and never exploded !
![Cool 8)](https://www.eevblog.com/forum/Smileys/default/xcool.gif.pagespeed.ic.cOxV6sPNRd.png)
But I am noty chancing it, the LPG tnak is empty and I only run on E85 instead !
![Laughing :-DD](https://www.eevblog.com/forum/Smileys/default/smiley_laughing.gif.pagespeed.ce._hfWAz_QHO.gif)
This evening in the news we learned that this morning not one but two electric buses caught fire and burned to the ground. Two the same day... and completely unrelated. One in Paris the other one down south in Carcassone IIRC. No electric for me thank you !
![Laughing :-DD](https://www.eevblog.com/forum/Smileys/default/smiley_laughing.gif.pagespeed.ce._hfWAz_QHO.gif)
Oh wait, that's an electronic forum, almost forgot !!
![Laughing :-DD](https://www.eevblog.com/forum/Smileys/default/smiley_laughing.gif.pagespeed.ce._hfWAz_QHO.gif)
Quick update on the scope, from a time where batteries didn't explode just because of the phase of the moon.
So I tried poking the scope itself rather the CRT.
Checked the power rails. Like in Tek scopes there is a -150V rail that's regulated and the other rails follow.
It was at -152+ volts. I adjusted it to spot on -150.0V because the trimmer is not touchy, it was easy to do.
Then measured the other rails, and they read a bit high. 305 for 300V, 106 for 100V.
Had a quick probing around, the grid of the tubes get a bit too much voltage so I guess it's just some resistors that drifted high.
Will fix that later if the scope proves to be fixable, but for now it's good enough, no need to waste time on this.
Then I went to do some cleaning of the little HV board, because so much black dust and fluff, not good for HV eh ?
So poured some IPA, gave it a quick brush... but access to the board is not great with those two tubes on it, like the World Trade Center.
So I removed them to make it easier to brush the board. Put them on the bench, they quickly rolled onto my lap, then fell on the ground, and shattered in a million pieces.
Problem is that I don't have many of this type of tubes !! IT's a 12AU7. Every Tek scope has one or two, but that's it, and I have already used up 5 of them to populate that HP scope !
![Scared :scared:](https://www.eevblog.com/forum/Smileys/default/scared.gif.pagespeed.ce.oZptHNcbsD.gif)
Worse, much worse... the other tube is a 6AQ5 . It's the oscillator tube. This one resided in only TWO of my Tek scopes, and they only have one inside, because they too use it as the oscillator tube.
- Type 310A. This one is NIB condition, a museum piece, I am NOT touching it. I even doubt it has ever been powered up at all, it's that good.
- Type 515A. I have two of them, so two tubes I could use. I want to restore one of them, the other one is there to help with that.
So I stole a 6AQ5 and 12AU7 from on of the type 515.
Result : no HV ! I used my HV probe and probed directly at the connector that plugs at the back of the CRT. I get ZERO. No HV-ing going on, not a sausage
![Banging Head |O](https://www.eevblog.com/forum/Smileys/default/bangheadonwall.gif.pagespeed.ce.8iLbFYV4Bc.gif)
Bad tubes ? As I said it's not like I have a zillion to try out !
![Angry >:(](https://www.eevblog.com/forum/Smileys/default/xangry.gif.pagespeed.ic.0w4zhwjvDw.png)
So that's were I am now, trying to probe on that HV board to see if I can troubleshoot it, hoping my tubes are good and there is something else wrong with it... hopefully not a burned HV transformer
![Roll Eyes ::)](https://www.eevblog.com/forum/Smileys/default/rolleyes.gif.pagespeed.ce.XcUK202Yqt.gif)
Problem is that access to that board is not ideal. I can get to its bottom because of the way it's installed in the chassis. I can only probe the top, and that's not easy as most interesting components are by the read panel. Hard to get probes down there, or see what you are doing really. Also, the caps mostly can't be probed as they sit flush on the board, their terminals are not exposed
![Sad :(](https://www.eevblog.com/forum/Smileys/default/xsad.gif.pagespeed.ic.L3FGyzQrjB.png)
So I am not happy. Lots of time and cursing will be involved in diagnosing this HV board I think
![Sad :(](https://www.eevblog.com/forum/Smileys/default/xsad.gif.pagespeed.ic.L3FGyzQrjB.png)
You can now resume your normal off-topic discussions, I apologize for the interruption !
![Embarrassed :-[](https://www.eevblog.com/forum/Smileys/default/xembarrassed.gif.pagespeed.ic.zcm3EmNu9T.png)