HP 3563A part ID? - Page 1
Forum section: electronics / repair

author: TheHockeytowner
author_rank: Newbie
timestamp: May 10, 2025, 07:06:53 pm
content: Hello all, long time lurker, first time poster, and I'm asking for your help:I purchased a broken 3563A Control Systems Analyzer recently, and thanks to this forum I repaired it successfully (2x shorted tantalum caps on the 1345A display unit's XYZ amp/stroke generator board plus a dead battery on the CPU board).However, before I repaired it I found these small plastic disks rattling around inside of the analyzer. Does anyone know what they belonged to? I'm totally stumped.Thank you for your time and consideration!

author: Whitefoot
author_rank: Contributor
timestamp: May 10, 2025, 07:45:29 pm
content: Only a guess - they look like insulators for transistors. The extra holes may be to accommodate a ground lead for shielding.

author: Andy Watson
author_rank: Super Contributor
timestamp: May 10, 2025, 07:48:00 pm
content: They are spacers for transistors.Back in the day, transistors would be soldered down to the PCB. Some would sit flush with the PCB, particularly the metal can variety. These spacers elevate the metal can and prevent it shorting to the tracks and pads under the transistor. They might also allow better air circulation.

author: TimFox
author_rank: Super Contributor
timestamp: May 10, 2025, 08:06:36 pm
content: Unfortunately, those insulators are hard to find now.I used to have a marketing brochure from a manufacturer that had samples for their line, but I have used them all up.A recent eBay listing for mass quantities:https://www.ebay.com/itm/284643332991?chn=ps&mkevt=1&mkcid=28&google_free_listing_action=view_item&srsltid=AfmBOoqNnZ1EIb4KLb2RBaKO-_uJrTu63QJQk7ae46ZLDRYkhuqHMBtH0WY

author: factory
author_rank: Super Contributor
timestamp: May 10, 2025, 08:46:06 pm
content: There were a few companies making them, in the UK we had MECI making Transistor Mounting Pads (aka Transipads) for transistors, diodes & can package ICs, sadly they've since been taken over and all the pdf catalogs that were available only two years ago have been unceremoniously deleted, the one with the range of mounting pads wasn't downloaded by me or saved by the web archive.Fischer Electronik also made them, some data attached.David

author: TheHockeytowner
author_rank: Newbie
timestamp: May 10, 2025, 10:43:34 pm
content: Thank you so much for all of your replies! I wonder why they were rattling around in the first place...

author: ZGoode
author_rank: Frequent Contributor
timestamp: May 12, 2025, 05:42:15 pm
content: I don't remember seeing any spacers like that when I worked on the cards in my 3563A. I'd be willing to bet they could have fallen in from a workbench or something possibly whenever the previous owner worked on it? I did take a brief glance at the service manual to see if there was any mention of spacers in the BOMs, but weirdly enough the document I have only has schematics, no part lists.I can open up my 3563A when I get home later to take a look and see if there are any used anywhere.

author: TheHockeytowner
author_rank: Newbie
timestamp: May 13, 2025, 12:00:36 am
content: Quote from: ZGoode on May 12, 2025, 05:42:15 pmPlease don't bother, I'm going to leave well enough alone