- Radiation Alert, Monitor 4 repair - 2 Updates
- Hantek - 4 Updates
| whit3rd <whit3rd@gmail.com>: Dec 25 12:14PM -0800 On Wednesday, December 25, 2019 at 2:08:45 AM UTC-8, William Beaty wrote: > These little GM counters have a typical failure: the 500VDC voltage falls low,... >three zeners in series are used as feedback reference: one of 1N5272 at 110V, and two of 1N5281 at 200V (to create a 510V zener.) > I found that all three were damaged and leaky For HV use, these parts should have long lives (they're glass/metal packages, no epoxy). How old IS that unit? Has it been in any odd environments (neutron flux?) ? Replacement with 1N5388 might be a good idea; the axial parts are stil metal/glass, just have an epoxy overcoat. Surface-mount packages, though, I'd be less sure of. The glass-package parts DID have some light sensitivity, sometimes, so testing for leakage can be an interesting challenge. |
| Jeff Liebermann <jeffl@cruzio.com>: Dec 25 07:32PM -0800 On Wed, 25 Dec 2019 02:08:42 -0800 (PST), William Beaty <billb@eskimo.com> wrote: <https://seintl.com/radiation-detectors/monitor-4/> >resistors of value between 1M and 4M. They still checked >out as diodes. But they were conducting at much lower >voltages than their rating. Offhand, that sounds to me like a dirty, leaky, or water logged PCB. Did you test the diodes with at least one lead lifted from the PCB? If you measured the resistance while the diodes were on the PCB or you did some soldering on the PCB, clean both sides of the PCB first with distilled water, and then with 91% (or better) isopropyl alcohol. If there's no conformal coating, try acetone: <https://www.youtube.com/watch?v=Bus-pdiHLq0> My Geiger counter doesn't count (sob sob) <https://www.edn.com/my-geiger-counter-doesnt-count-sob-sob/> I have known them fail due to HV leaking from the tube across the PCB. The board has to be very clean, free of any flux etc. Often commercial ones are attached with Teflon spacers to minimize charge leakage. >They caused the -HVDC value to be around -260V, so the >geiger tube wasn't counting. Again, you could be measuring board leakage, not diode leakage. >a 4.7M resistor which leads to the GM tube. All three diodes are in series. >I didn't have any 1N5281 on hand, so I tried a 1N5279 (180V, >not 200,) and the unit woke up and worked fine. What you might have done is vaporized any water (or contamination) around the solder pads. >is down by about 8%, if low by 20+20=40V) >Note that there's a trimmer pot on the PCB. Possibly for meter >calibrate? I didn't change its setting, measured at 362 ohms. Dunno. I couldn't find an inside photo or a schematic. My guess(tm) is that the pot is in series or across the meter to set full scale. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
| stratus46@yahoo.com: Dec 25 01:27PM -0800 On Tuesday, December 24, 2019 at 5:40:05 PM UTC-8, Cursitor Doom wrote: > >overheard a couple of men at a hamfest talking scopes and they said the > >Hantek was a better scope. > I think you'd best delete that comment before JL reads it. ;) <snip> I don't think JL has issues with Rigol vs whatever. I have a Rigol DS1054Z and have hacked it to turn on all the options. It reports itself as a DS1104Z (100 MHz version). The case does not need to be opened so the tamper seal is intact. It's a lot of scope for $350. Display freeze between triggers is very helpful when sorting out serial data transfers. Its decoding of the serial stream is also useful. Merry Christmas G² |
| Ralph Mowery <rmowery28146@earthlink.net>: Dec 25 05:20PM -0500 In article <8144d537-387f-4442-bd17-60d93080afb0@googlegroups.com>, stratus46@yahoo.com says... > I don't think JL has issues with Rigol vs whatever. I have a Rigol DS1054Z and have hacked it to turn on all the options. It reports itself as a DS1104Z (100 MHz version). The case does not need to be opened so the tamper seal is intact. It's a lot of scope for $350. Display freeze between triggers is very helpful when sorting out serial data transfers. Its decoding of the serial stream is also useful. > Merry Christmas > G² Some of the electronics comming out of China is a lot for the money. One reason given for the Hantek was it had a larger screen. Very helpful it you turn on the on screen measurments. I don't know about other digital scopes as I have not used any, but my only complaint so far is that if doing an XY display the circle and other paterns just do not work or show up as clear as they do on the older analog scopes. |
| Fox's Mercantile <jdangus@att.net>: Dec 25 06:08PM -0600 On 12/25/19 4:20 PM, Ralph Mowery wrote: > I don't know about other digital scopes as I have not used any And then there's the gold standard of digital scopes. The HP infinium. I have one in my shop I acquired for next to nothing. <https://i.ebayimg.com/images/g/R2EAAOSw6btXTP8Y/s-l1600.jpg> -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| Ralph Mowery <rmowery28146@earthlink.net>: Dec 25 07:39PM -0500 In article <mOedndHSC792ZJ7DnZ2dnUU7-e_NnZ2d@giganews.com>, jdangus@att.net says... > The HP infinium. > I have one in my shop I acquired for next to nothing. > <https://i.ebayimg.com/images/g/R2EAAOSw6btXTP8Y/s-l1600.jpg> No argument here if one has the gold, or as in your case acquire it for next to nothing. |
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