kennethw (12/09/82)
I've received a number of replies to my request
for ideas on boot up problems with an H89. To summarize
the problem, my H89 has problems booting up when first turned
on, but seems to be fine when warm.
The following responses have been culled from a larger
list and are represenative of the suggestions.
From: tekcrd!tekid!bentonh
To: tekcrd!azure!kennethw
Subject: re: cold bugs
Date: Mon Nov 15 15:44:17 1982
I've had problems with having to re-form (electrolytic?)
dielectrics in photo-flash caps. My Braun BC23 needs to be
cycled several times after sitting uncharged for more then a
day, to get the leakage down to a point that the voltage will
go high enough to light the neon indicator.
Unless your supply caps are VERY leaky tho' (leaky enough
to pop the line fuse, I'd think) I wouldn't expect this is
your problem. (So why have I gone on so long about it??
Good question.)
Benton Holzwarth
...tekid!bentonh
From: tekcrd!teklabs!ucbvax!devon@mit-mc
To: teklabs!tekcrd!azure!kennethw@UCB-C70
Date: 20 November 1982 02:03-EST
Subject: [Berkeley: Cold Microcomputer Bugs]
Message-Id: <8210200716.21365@UCBVAX.BERKELEY.ARPA>
Received: by UCBVAX.BERKELEY.ARPA (3.227 [10/22/82]), id A21359; 19-Nov-82 23:16:38-PST (Fri)
I have a 32K board with an apparent bad trace or IC socket that works when warm
but not cold. Maybe the metal expands and closes a hairline crack???
I suppose your problem could be a transistor driving the head stepper that can't
put out enough current until it heats up to operating temperature.
From: tekcrd!teklabs!ucbvax!plk@mit-mc
To: teklabs!tekcrd!azure!kennethw@UCB-C70
Date: 21 November 1982 02:14-EST
Subject: Cold Microcomputer Bugs
Message-Id: <8210210723.17803@UCBVAX.BERKELEY.ARPA>
Received: by UCBVAX.BERKELEY.ARPA (3.227 [10/22/82]), id A17799; 20-Nov-82 23:23:39-PST (Sat)
I have to let mine warm up a few seconds. Don't have any idea what
the problem is.
From: tekcrd!teklabs!ucbvax!pearson@sumex-aim
To: teklabs!tekcrd!azure!kennethw@UCB-C70
Date: 24 Nov 1982 1928-PST
Subject: Re: Cold Microcomputer Bugs
Message-Id: <8210250206.12337@UCBVAX.BERKELEY.ARPA>
Received: by UCBVAX.BERKELEY.ARPA (3.227 [10/22/82]), id A12269; 24-Nov-82 18:06:54-PST (Wed)
In response to your message sent 18 Nov 1982 0007-PST
Here is a quick summary of Heath H89 problems I am familiar with.
1. The connectors that connect the powersupply rectifiers to the low
voltage AC are marginal. Many people have removed them and made a direct
solder connection or replaced with heavier connectors.
2. Same with the connector that brings 5V onto the main CPU board.
3. The ground return from the main CPU board is marginal, sometimes
as much as 0.5 V above ground on the powersupply.
I have a fully loaded system which makes these problems more obvious.
Fiddling with power connectors or a voltmeter helps.
4. (I forgot) there have been many flakey rectifier problems
I should mention that I think the H89 is great, especially ow that you
can put one together for less thatn 1.1K. But there are occasional
problems.
- Bill Pearson
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