[vcf-midatlantic] Repairs to a Heath WH19 Terminal
perkins.jason at gmail.com
Wed Mar 15 22:17:53 EDT 2017
Replacing the shorted cap and blown current limiting resistors results in
signs of life!
Good: The terminal works! https://goo.gl/photos/TPoPQ1c8QajthkZM7 (yes, I
tested with a loopback adapter, then with a usb to RS232 adapter before
hooking it up to the Lisa :) ) The terminal draws 51 watts running. Nothing
inside seems to be getting unusually hot.
Problems: The display has a major wave.
https://goo.gl/photos/wXKydMr5syKU1SWd7 Guessing there are more bad caps in
the video section. The 65V input, and 53V rail in the monitor have .5v of
ac ripple. Perhaps the big 1500uf electrolytic is going bad...
The keyboard didn't work very well at first, but after typing on it for a
bit it now works perfectly.
On Mon, Mar 13, 2017 at 12:10 PM, Jason Perkins <perkins.jason at gmail.com>
> Man what a small world... My other big not-work time investment is
> TDIClub, looks like the OP of that article is into TDIs a bit as well!
> On Mon, Mar 13, 2017 at 11:56 AM, Neil Cherry <ncherry at linuxha.com> wrote:
>> On 03/12/2017 11:25 PM, Jason Perkins via vcf-midatlantic wrote:
>>> You were right, the big .22 600v cap C232 was shorted. I've placed an
>>> from DigiKey, hopefully the impending snow doesn't delay things too
>>> On Sun, Mar 12, 2017 at 6:55 PM, David Gesswein via vcf-midatlantic <
>>> vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
>>> On Sun, Mar 12, 2017 at 05:43:22PM -0400, Jason Perkins via
>>>> vcf-midatlantic wrote:
>>>>> There aren't many things on that ground return from the flyback, I'll
>>>>> them out one at a time till I find the shorted part.
>>>>> The caps to ground look like the most obvious path to create a short.
>> Queue eerie Twilight Zone Music:
>> ... but he quickly determined that a bad cap was shorting out the -12VDC
>> rail ...
>> Linux Home Automation Neil Cherry ncherry at linuxha.com
>> http://www.linuxha.com/ Main site
>> http://linuxha.blogspot.com/ My HA Blog
>> Author of: Linux Smart Homes For Dummies
> Jason Perkins
> 313 355 0085 <(313)%20355-0085>
313 355 0085
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