Solder Problems (PDP-8/m related)

From: Joe <rigdonj_at_intellistar.net>
Date: Thu Dec 2 18:57:03 1999

At 01:22 PM 12/2/99 -0800, Zane wrote:
>>Argh!! You've got an intermittant connection, and they're the _worst_ to
>>trace...
>
>
>Well, once I got the face plate off yesterday I was able to wiggle the LED
>itself in its 'socket' and it would come on.

   You may have corroded LED sockets, specially since you said it had been
left outside.

>
>>When 2 instruments disagree you really should investigate further. Yes,
>>it may be that one instrument can't see the pulse (it's just too narrow
>>for it). Or you might really be seeing noise on a ground connection or
>>something.
>
>Oh, wonderful. I just took both the scope and the logic probe to both E46
>and E39. They both gave the same results, the chip looks to be good.
>Something tells me this system is going to drive me crazy! But it means
>that what the scope told me a couple days ago is correct.
>
>>This machine sounds as though it's full of bad connections, alas. Have
>>you cleaned _all_ the edge fingers on all the boards? Have you cleaned
>>(and tightened if necessary) the PSU connectors. Have you cleaned the
>>backplane slots?
>
>I cleaned the edge fingers before even turning it on, though I think I'll
>clean them again. I'll have to take a look at the PSU connectors. I blew
>out the backplane slots with canned air, how can you do a better job of
>cleaning them?

   I use an old punch card and fold it in half a couple of times till it
fits snugly in the gap and then dampen it with alcohol and work it around
in the slots to clean them. Of course if you had a HP you wouldn't have
these problems. :-)

>
>>Has it been stored under poor conditions?
>
>Not since I got it a couple weeks ago, before that I've no idea. I suspect
>it might have spent a short amount of time outside as I found a couple pine
>needles in it.
>
>>Personally, I use a Weller TCP iron. It's one of the Magnastat
>>temperature-controlled ones. It's a lot simpler (== less to go wrong)
>>than an electronically controlled iron, and it's Good Enough for
>>everything I'm ever likely to want to do with it. I find the #7 tip too
>>cold for many things and generally have a #8 in it.

   I agree. I have a Weller and it works perfect. I've been told that they
no longer make the magneticly operated irons so you may have to find a used
one. BTW the number on the back of the tip (7, 8, 9, etc) indicates the
temperature that it regulates at. 7 = 700d F, 8 = 800d F, etc. The local
surplus place has a large variety of tip styles and temperatures so I have
plenty of different ones to work with. I like to use a hot one (800d) for
unsoldering so I can heat the joint up and get the iron off of it quickly.
But I use a 500 to 600d one for general use.

>>
>>This iron is very popular with serious hobbyists and research/development
>>labs in the UK, which is probably a good recomendation.
>
   Same here in the eastern US. FWIW I also have a couple of PACE solder/
desoldering stations but I never use them. Too big and ackward and they
don't work a bit better than the Weller.

   Joe
Received on Thu Dec 02 1999 - 18:57:03 GMT