HP 28 misc...

[rprosperi]

(06-21-2018 12:48 PM)Thomas Okken Wrote:  The main drawback of the 28, and probably the reason why they tend to sell for cheap, is the lack of external storage.

Though lack of I/O (well, I anyhow, I guess IR printing must qualify as O) is a big limitation, I think the larger reason these machines are not too popular and relatively cheap, is the terrible battery door/door frame design.

Almost every Champion series machine that has actually been used a lot has a broken or cracked battery door, or more often, the door frame. This is due to the aging plastic becoming brittle and the continuous strong pressure exerted against the door by the battery springs. Be VERY careful when removing and inserting the door - use your fingers to depress the batteries when moving the door along the small channels in the frame that the metal edges slide within.

Oddly, the business series Champion machines (18C, 19B and 19BII) seem to have this damage less often than the 28C/28S; perhaps this is because Business machines are used less and/or treated better. As a result, these often go for higher prices than the Scientific machines. If you plan to buy any Champion machine from eBay, etc. be sure to ask seller about door/frame condition and ask for photos of that area. If damaged, you will be able to see the cracks or chipped edges, and sometimes it just looks like the door is installed but bulging out. An undamaged door/frame will appear smooth and barely visible thin crack along the door edges.

Late production of the 19BII changed to a totally different battery bay design, with a door on the back of the machine that is not subject to the battery spring pressure. These are much nicer, but are also accordingly more expensive.

IMHO, this is the worst battery bay design of all HP machines, as basically all examples will degrade in use over time.