EZ os5060a oscilloscope arcing - Page 1
Forum section: electronics / repair

author: mattg
author_rank: Newbie
timestamp: January 31, 2017, 04:48:36 pm
content: Hello Everyone,I acquired a EZ os5060a oscilloscope off of ebay. The unit powers on and displays traces and seems to work correctly. The only thing wrong is occasionally I will hear arcing. After opening it up it looks like there are a couple of hv arrestors (look like neon bulbs)- this is where the arcs are coming from. When it does arc, the display goes blank but comes right back. I cannot find a schematic for this thing anywhere. Does anyone have a schematic or any ideas of what could be the problem?Thanks!Matt

author: Armadillo
author_rank: Super Contributor
timestamp: January 31, 2017, 08:07:00 pm
content: Use compressed air, blow away all the dust  especially at the areas of arching. Then use WD40, spray at the areas of HV.Check if there are still arching.Be careful high voltage, discharge capacitors, make sure take many photos before you blow things out of place. If you are not certain, let the pro do it.

author: Gyro
author_rank: Super Contributor
timestamp: January 31, 2017, 08:15:51 pm
content: Yes to the cleaning, a definiteNOfor the WD40.Yes it is a moisture dispersant, but it will also attract dust and make your problem worse. Not to mention possible damage to components!Compressed air is good for blowing dust out, but for cleaning any baked on dust or other contaminants off the board then something like IPA (Isopropanol) would be much safer.Warning: Make sure that everything is safely discharged before starting - if you don't know how to do this, then probably don't attempt it.

author: james_s
author_rank: Super Contributor
timestamp: January 31, 2017, 08:19:05 pm
content: I suspect that the arcing is internal to the CRT. Those little gas discharge spark gaps are meant to protect the electronics from these incidents, so if they're being triggered then it's probably due to a CRT fault. I've seen this happen before when a flake of aquadag comes loose and falls down into the neck. I also had a scope where a little metal tab had broken off of somewhere and was sliding around loose inside the CRT, it worked fine as long as it was stored and used horizontal.There's a reasonable chance that the fault will eventually clear itself and stop happening, or you may be able to carefully tap the neck of the tube just right in order to dislodge it. Take care not to break the glass.

author: Armadillo
author_rank: Super Contributor
timestamp: January 31, 2017, 08:36:57 pm
content: Quote from: Gyro on January 31, 2017, 08:15:51 pmDust will come anyway and either way...... spray again, it provides a layer of coating. No it will not damage the electronics. I have done it many times.But if you are not sure, don't do it.

author: james_s
author_rank: Super Contributor
timestamp: January 31, 2017, 08:42:07 pm
content: Don't forget that WD40 is flammable, it's mostly kerosene/paraffin oil, and it stinks too,I would never use it on electronics.Actually I don't use WD-40 on much of anything, it's a bit like a spork, it tries to do everything but it doesn't do much of anything as well as more specialized products.Electrical contact cleaner is a much better choice if you want to remove contaminates from a PCB.

author: mattg
author_rank: Newbie
timestamp: February 01, 2017, 03:49:00 am
content: Thanks!I think james_s is on the right path. I did notice that after moving it around and trying it again the problem seemed to go away. The inside looks really clean but I will blow it out anyway.

author: Armadillo
author_rank: Super Contributor
timestamp: February 03, 2017, 01:04:30 pm
content: Quote from: james_s on January 31, 2017, 08:42:07 pm

author: james_s
author_rank: Super Contributor
timestamp: February 03, 2017, 07:04:08 pm
content: Apparently there are now other products under the WD-40 name. The WD-40 I was thinking of is the classic general purpose water displacement stuff in the blue and yellow can.

author: Gyro
author_rank: Super Contributor
timestamp: February 03, 2017, 07:48:54 pm
content: Definitely not the same WD40 that we were thinking of!Unfortunate name clash!