HP 120B scope update
Oh not yet another of his updates, he pisses us off, someone please tell him to shut the fuck up !
Don't worry... this is the very last update on this scope... I have just received my new 6AQ5 oscillator tubes, so I started working on the scope again.
After only 30 minutes it was declared dead. It is now officially unfixable, 100% certain, it's a door stop.
For the few who actually care about the details... well here is what happened.
...snip...
So.... end of story.
I still like this scope very much and would love to see it fixed and working, so I can play with it but.... bad transformer and dear CRT, that's too much for me
so I will button it back up and maybe in 10 years I will find a cheap parts mule to fix this one, or the other way around, use this one as a donour to fix a twin brother.
But I am not holding my breath. I am not going to find another of these ever, over here. It was an impulse buy because it looked cool, was HP, was free and in good nick... so I felt it deserved to be saved but... it does not want to be saved it seems
So if someone finds another one of these dirt cheap, in bad condition, so I can salvage a CRT and transformer as well hopefully... don't hesitate to contact me !
That's all for this scope.... I am well pissed.
Oh no... that's some bad luck, the 130C (same CRT) might be easier to find in the EU, but still not that common compared with Tek. I wonder if the transformer problem is due to the washing and it maybe not dried out enough.
As for the USA, there are three 120Bs & three 120As on ePay.com, cheapest is $95, but either no shipping or $$$ too expensive to move. No sales that I can see for the last few months.
Keep a search for CRTs in the EU as most sellers seem to prefer to destroy than sell complete.
David
I don't think it's the washing... I didn't hose it like Papy Smurf said. I sprayed detergent and rinsing water carefully, one small area at a time. I obviously did not inundate that poor transformer.
Also, after washing / drying it remember, I powered it up and let ir ran for several hours without any problem.... albeit with no HV since it didn't work.
The problem started magically when I put the NOS tube. I think it did finally get the HV working full blast, and that pushed the insulation of that CRT heater winding in the transformer, to the limit, it gave up.
I am sure if I just disconnect that winding, that would relieve that transformer from that HV "stress" and it would be just fine (again, all other windings / power rails still work perfect, it's just the heater winding that arcs). So it should not be too hard to cobble together a standalone heater power supply, I would think.... so the transformer really is not my biggest problem. The real show stopper is the broken CRT...
I never go to Ebay to search for TE, I only use our local Leboncoin.fr website, but I guess now is the time to change habits... Ebay is my only realistic hope of ever finding a scope or CRT... I guess I can setup an automatic search so that I get notified by e-mail automagically.
EDIT : OK I guess next time I won't tempt the devil and will take the time to remove the transformer. It didn't even have that many wires on it, unlike a Tek transformer which I would never dream of having to remove !