dave.g4ugm at gmail.com
Sun Nov 9 03:33:36 CST 2014
> The "wirewrap" pins on the 11/23 and many other DEC boards are short pins
> that are accessed on the /component/ side of the board and used for jumper
> links, eg to select baud rates, or in the case of an 11/23 to set the boot
> configuration and other things. See for example the images at
> There's a group of pins with their jumpers to the right of the middle
On that pic those links look like a DIL socket, not wire wrap pins. But if
wire wrap pins are used like that its not surprising they work loose.
I would expect them to be plated steel and therefore have characteristics
that are bad for soldering. That is:-
1. Have a relatively large mass as they need to be stiff to wire wrap
2. Therefore have a large thermal mass or heat capacity
3. So they are slow to heat up -> may not get hot enough to solder
4. Slow to cool -> likely hood of dry joints if they move while cooling
5. Poor solder whetting as they can be hard to clean....
So not surprising they sometimes work loose.
> Look carefully and you'll see 5 (IIRC) other pairs, including one near the
> left of the crystal oscillator with a jumper on it, and one with no jumper
> the right of the smaller IC two rows above the main jumper group. Other
> DEC boards such as DLV11J and the notorious (because of gazillions of
> options) MXV11B do actually use wirewrap to such pins rather than jumpers,
> in a few cases 2-level wrap.
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