On 01/19/2017 01:12 PM, Alan Hightower wrote: > > > One caution about isopropanol. I keep a lot of 99% around for > post-cleaning electronics assemblies, soldering, etc. I used to use it > as a general cleaning and de-greasing agent for most vintage computer > things until several plastic and a couple painted surfaces showed > changes not in color but specular reflection. It's like a change in flat > vs gloss where you could see my swirl marks, etc I made while cleaning. > I was able to mostly smooth it out later with more diluted solution, but > it surprised me. > > If using isopropanol to clean, I recommend starting with a 70% or less > (dilute with water) drug-store type solution first until you know your > surface is safe. > > Also when cleaning anything electronic, especially in dry winter, make > sure you are well grounded. If your house is built on a slab and you > have an exposed concrete floor in the lower level, consider moving your > work-shop or work-area there! > > -Alan > > On 2017-01-19 12:18, Andy Cloud wrote: > >> Hey all, >> >> So one of my recent acquisitions is looking quite grubby, outside it just >> looks like surface dirt on the plastic, inside seems dusty/basement dirty. >> >> My question comes in two parts: >> >> 1. What do you use to clean the exterior plastic and/or metal if >> applicable? I'm always worried about staining the plastic using strong >> solvent... could you also include what type of cloth/sponge/anything you >> use :) >> >> 2. You guessed it! What about internally? I've heard isopropyl is really >> good, but how do you apply it? What do you use to apply it in order to make >> the board shine as if it was just bought!? :D or if you use anything other >> than isopropyl... >> >> I also have a bonus question, how do you ground yourself to ensure you >> don't blow a component? Is an ESD wrist strap good enough? >> >> I absolutely love this group, really enjoyed your previous answers >> regarding rarest/unusual machines!! >> >> -Andy > > First and foremost I set out what goal I'm trying to achieve. Things like simple grime removal or preparation for major repairs or simply a surface cleaning to remove things like hand prints.
An example of surface cleaning would be a functional KayproII that needs a dirty crt and some external smudges removed. For that glass and counter cleaner may be adequate. Another was be a stack of PDP-11 Qbus boards from a shed. Dirty maybe some guano or bugs and require testing and maybe repair. Those will have all labels accounted for (markings and tags), then socketed chips removed and stored then into the dishwasher with a mild detergent. After that a beak in a 160 degree oven (dryout). Then the boards will be remarked if needed and socketed chips reinstalled pending testing and repair. A though cleaning helps with flaky cheap sockets and getting them dried. It also removes the grime layer that tends to contaminate soldering resulting in poor joints. In rare cases ( more likely radios) I use a pressure washer. I had one computer come to me that was intact but just plain filthy with dust, dirt and maybe wildlife leavings. Boards that could be removed were and dish-washered. The case and power supply was pressure washed with a mild detergents then rinsed. Fortunately the late July sun was intense enough to dry it quickly. Some parts were then removed for a bake (power transformer). Switches were de-watered using isopropanol (91%) and air dried. Any moving parts were given a suitable lubricant. That machine after some minor repairs (bad side wipe sockets) and missing parts restored(SA400 drives) runs without issues and looks near pristine. Outer cases, I rarely resort to harsh materials. Isopropanol is with exception not used on painted or plastic unless it can remove the specific gunk milder things have not touched. I've found glass/counter cleaners and a soft rage to be adequate. I do not have an anti-yellowed plastic fetish and generally leave it at clean unless I'm trying to match parts. Anything that brings plastic back usually does two things, weakens or destroys the surface finish and may lead to cracking or it just yellows faster. The latter is significant as I tend to keep things for a long time (decades). Metal cases with damage or scratches are on a "it depends" basis. I may remove bends or dents if it makes it easier to use or repair. Paint I may or may not touch up or completely redo. I have a few that got a full paint job not to look like original but to what I would have done if purchased new (it was fugly, new paint!). For those preservationists don't have apoplexy those are likely to be common. If anything the highest is that I try to do as little as possible and just keep and use it. A lot of this reflects my underlying reasons for collecting. First being I always wanted one to play with where time and dollars were not forthcoming to do so. The other is the occasional true rare find that stays and may even get repairs and used and kept safe. Other are remainders and reminders of my days on the cutting edge (Altair 8800) that either still work or were FISH (First In Stays Here) and maybe even became part of my junkbox to be pulled out as "valuable do not destroy". I do have a collection of personal oddities. Things found that were re-purposed for example. The best is a BA11VA box save for it was a proto in aluminium and devoid of anything inside. An AmproLB+, 3.5" floppies, Fujitsu scsi 45MB hard disk and a random power supply were fitted into it over 30 years ago and lives there still in it original DEC Gray 68. In the end cleaning has to do several things. Remove things that may be hazardous to the longevity of the unit(artifact) or the user. Bring the unit to a usable functional state. For the odd beauty pageant aka static non functional display items look like new and pretty. Allison
