Fluke PM3370b CombiScope - CRT issue  - Page 1
Forum section: electronics / repair

author: neg_feedback
author_rank: Newbie
timestamp: April 03, 2015, 06:48:40 pm
content: Hi,I just joined the EEVblog after having watched many of Dave's videos sporadically over the last few months. I've decided to start electronics as a hobby and I really enjoyed Dave's post about what is needed to build a good starter lab.I took a chance and bought a used Fluke PM3370b CombiScope for a little over a $100. The listing had a powered on picture so I felt reasonably assured that the unit would at least turn on on show a trace.The unit arrived yesterday and other than a set of dead AA batteries in the battery case on the back the unit was in good shape.The unit started up and I ran a self test which it passed and the unit displays the test post trace just fine on both channels. However after about an hour of use the CRT screen shifted down a little more that 2 blocks from the center line. At first the screen would jump back and forth from normal to shifted but now it stays shifted all the time even between power down and power up and on power up after a long 90 minute cool down period.Has anyone seen this behavior before? If so could you advise on whether it is something that could be fixed easily?I can post a picture if it helps,Thank you.

author: tautech
author_rank: Super Contributor
timestamp: April 03, 2015, 07:15:33 pm
content: Welcome to the forum.Find a Service manual for it.Check all PSU votages are to spec.Plenty of links in the first thread on this board.Also get the Tek troubleshooting pdf in the first post on the board.Hopefully the manual will have some easy to do DC checks on the schematic.These are best for when one has limited test gear.There will be a particular way in which the scope must be set in order for the test point reading to apply.

author: HighVoltage
author_rank: Super Contributor
timestamp: April 03, 2015, 07:26:42 pm
content: The "B" versions of these scopes are usually really stable and reliable.If a problem arises, they are usually easily repairedIf you can not find the service manual, I can upload it for you.The files are too large for an attachment

author: neg_feedback
author_rank: Newbie
timestamp: April 03, 2015, 07:43:02 pm
content: I'm not having much luck except for a $300 bin on eBay.I did find the PDF versions of the SCPI user manual, regular user manual, reference manual, and a service manual for the "A" series units.Would the "A" series service manual cut it here?

author: tautech
author_rank: Super Contributor
timestamp: April 03, 2015, 07:51:47 pm
content: http://elektrotanya.com/fluke_pm3370b_pm3380b_pm3390b_pm3384b_pm3394b_oscilloscope.pdf/download.html

author: HighVoltage
author_rank: Super Contributor
timestamp: April 03, 2015, 08:22:21 pm
content: There were a lot of hardware and software changes from the A to the B versionSo it is better you use the service manual that tautech posted

author: neg_feedback
author_rank: Newbie
timestamp: April 04, 2015, 12:53:38 am
content: Thank you Tautech!

author: SaabFAN
author_rank: Frequent Contributor
timestamp: April 04, 2015, 11:08:52 pm
content: The first thing you could check is if the PCB attached to the back of the CRT is loose and if there are any other parts not where they are supposed to be inside the device. When my scope arrived with DHL, I discovered that the PCB at the back of the CRT was not flat on it, plus the Fan and the PSU were knocked out of their fittings.Even with "Fragile"-Stickers all over the packaging, DHL and probably other logistics companies also aren't too careful with them.