[SOLVED] HP 8563A tune up, hopefully brighten CRT  - Page 1
Forum section: electronics / repair

author: Cyclotron
author_rank: Unknown
timestamp: May 26, 2025, 12:55:46 am
content: I recently picked up a HP 8563A; reported as working. It does work but the CRT is dim and words on the display are inconsistent. Based on what I've studied, the CRT probably is mostly fine other than some burn in. The driver will need to be tuned up to correct the CRT brightness.The trace is bright, and when you select menu items they are bright. The grid is good. Its just the on screen information that appears to be out of sorts.So, I was going to jump right into doing those adjustments per the maintenance manual but I was shocked when I took the cover. The photos tell the story. I also read that leaky caps can cause brightness issues. Given the obvious constraints on cooling, I'm guessing the capacitors have seen their fair share of high temps. I've tested a couple and they are not completely gone but not hitting their specifications either. So, I'm order a full set of capacitors for the PSU and will get it all cleaned up.Then I'll run through the CRT adjustments to see where it lands. This is in my top ten of dirty systems. It had to be taken outside for clean up. The worst one I had was a computer for a lady that had cats and wore way way too much perfume. (I'm allergic to both) I had to sit the CPU outside and operate it with cables through my window to fix it as I promised.If anyone has tips, tricks, or commentary, I'm all ears. I have wanted the 8563A or E for a long while so this is hopefully going to solve that want once I get it fixed up.

author: Runco990
author_rank: Frequent Contributor
timestamp: May 26, 2025, 03:33:35 am
content: Make sure you record all the setup and correction values!!!Damn! That poor thing is FILTHY! Must have been just left running for YEARS.Don't forget to clean the front "glass". When I got mine, it looked like the CRT was dim, nope... it was just VERY dirty.

author: Cyclotron
author_rank: Unknown
timestamp: May 31, 2025, 02:27:41 am
content: It's all cleaned up with a fresh set of RIFA and other CAPs on the PSU. I ran through the calibration procedure for the display, and it is looking fantastic.A couple of lines of burn-in, but the brightness of the display looks great now, and it's ready for years of service at the rate I'll use it.It took forever to get all the dust out of the unit. I may replace the fan with something quieter.Where do get the setup and calibration values from? I've not read the manual yet but just going through the menus, I don't see anything like that.Attached is a pic of the freshened up unit.

author: Runco990
author_rank: Frequent Contributor
timestamp: May 31, 2025, 04:36:02 pm
content: I have an 8593E, which is different. Best to download the manual. It had a template you can print out to write the data on and store in a safe place. It tells you what menu to look. I also took pictures of each screen. If the battery dies, you'll wish you had it. Do it NOW.

author: Cyclotron
author_rank: Unknown
timestamp: June 01, 2025, 03:15:13 am
content: Quote from: Runco990 on May 31, 2025, 04:36:02 pmI've been through a few 8563A manuals, procedures, and GPIB command structures and can't find anything that references constants or setup values that I can record. I have a new battery and have read the replacement instructions. If I can't find a way to make these recordings, I will proceed with that replacement to be sure the values on the A2 board aren't lost.Thanks

author: Uunoctium
author_rank: Frequent Contributor
timestamp: June 01, 2025, 03:52:58 am
content: Just my 2ctAt changing the backupbattery i would recommend to bypass the original during the procedure with an Lab-Psu + resistor. I trusted the manual (8591), which stated the cmos is safe by the paralleled supercap during battery replacement for more than 24hrs.Nope!And the burnt-in graticule lines can be compensated through menue available H & V position alignment (slight pixel-shifting)

author: Cyclotron
author_rank: Unknown
timestamp: June 01, 2025, 02:13:13 pm
content: Quote from: Uunoctium on June 01, 2025, 03:52:58 amThe 8563A procedure says to plug it up, turn it on, and then replace the battery. Great tip. I'll first test the circuit to be sure it's being supplied by the unit with the main PSU before the swap. I probably will still do a lab power bypass just for sanity.

author: ME
author_rank: Frequent Contributor
timestamp: June 01, 2025, 03:16:08 pm
content: that looks minging!.

author: Runco990
author_rank: Frequent Contributor
timestamp: June 04, 2025, 03:02:57 pm
content: Make sure you use a NON grounded soldering iron if you replace the battery "live".