HP 8590L Dim Display - Page 1
Forum section: electronics / testgear

author: rheb1026
author_rank: Regular Contributor
timestamp: April 11, 2018, 04:56:54 pm
content: I recently picked up one of these locally for $200. It works great and is reasonably well calibrated (so far as I can test). Only issue is that the display is pretty dim. It's fine if I want to work in a dark closet...With the intensity knob at about 3/4 full intensity, it's in perfect focus, but if the knob is at full intensity it becomes out of focus.I can live with the dim display on full intensity if I could get it into focus. I looked through the manual and service manual and couldn't find anything about an adjustment for this. Is this non-adjustable?I guess the other option is to try to find another display. Does anyone know of a place where I can find one? Or is it possible to some how restore it?I see lots of LCD retrofit kits out there for the 8566/8568. Is there a similar one for the 8590? I tried searching to no avail

author: EE-digger
author_rank: Frequent Contributor
timestamp: April 12, 2018, 01:18:05 am
content: I had an 8590L when they first came out. Nice little unit.It has an Aux Video output on the back. I believe it is composite NTSC. You can run into a composite to VGA adapter (like the GB8220, low cost), the any panel with VGA input of your choice.It could also be run into a small LCD display with composite input but today your choices may be slim (ebay) and quality on non-pro models is generally poor.Regarding focus, I may be getting models confused but I'm pretty sure there are some controls accessed through the left side of the CRT module, thru the mesh holes. If you have intensity set very high the display will bloom though, and focus will not be as effective.

author: rheb1026
author_rank: Regular Contributor
timestamp: April 12, 2018, 02:52:16 am
content: Thanks very much for the information! I hadn't thought to look for a video output.And I'll have a look for that adjustment on the side of the CRT

author: james_s
author_rank: Super Contributor
timestamp: April 12, 2018, 05:17:59 am
content: Dim picture that gets blurry when the brightness is turned up is a classic symptom of a worn out CRT. There are some rejuvenation techniques you could try that may squeeze a bit more life out of it. Is this a conventional magnetic deflection tube or an oscilloscope style electrostatic tube?

author: RFDUK
author_rank: Regular Contributor
timestamp: April 12, 2018, 09:20:41 am
content: Poor brightness on HP 859X SA is sometimes improved by removing the screen bezel and protector (4 hex bolts) and cleaning the face of the CRT.A friend bought an HP 8594E that looked like a worn out CRT to find removing the dirt and dust on the CRT restored normal brightness.The very poor focus on yours when turned up does suggest you wouldn't be quite so lucky, but worth a look.

author: rheb1026
author_rank: Regular Contributor
timestamp: April 13, 2018, 03:06:58 pm
content: Thanks for the replies. I'm really not familiar at all with CRT technology, so I don't know what kind of CRT it is. Maybe someone else can comment?I tried removing the screen protector, but didn't have the correct size hex key. I only have SAE hex tools. Could these be metric screws?I tried fiddling with the little adjustment trimmer on the side of the CRT and I wasn't able to see any noticeable difference in focus even at the extremes of the range.I think the cheapest and easiest thing to do for now would be to pick up one of those cheap composite to VGA adaptors and just use one of my computer displays for the analyzer

author: james_s
author_rank: Super Contributor
timestamp: April 13, 2018, 04:54:20 pm
content: If it has a composite output then it's 99.9% certain that it's a common magnetic deflection CRT.I don't know where you are but if you're near the Seattle area you're welcome to drop by and I can try my CRT tester/rejuvenator on it. Otherwise any number of different displays ought to work.