[sebhc] H90

[Carroll Waddell]

Mark Garlanger wrote:

> Hi Carroll,
>
>  I have a copy of the Operation/Service Manual for the WH89 that I
> can let you borrow. Unfortunately, since I'm getting ready to move to
> Austin for a new job, it has been packed away in a box. It may be a
> while before I'll be able to send it. We still have to sell our house
> and buy one in Austin. I also have a TON of spare hardware, so once I
> do get settled in Austin, and depending on the issue, I may have a
> replacement part I could send you.
>
> Mark
>
> On 5/10/07, Carroll Waddell <carrollwaddell at sc.rr.com> wrote:
>
>> Does anyone have any troubleshooting experience on Heathkit H89? I
>> bought 2 (neither will work) hoping to be able to repair and keep at
>> least one.
>> I've swapped the terminal logic board with the one in my H19 terminal,
>> so I know the TLB is ok. The CPU board had several blown tantalum caps,
>> and I've replaced those. All the voltages check out ok with little to no
>> ac ripple. With a scope, I can see activity on the address and data
>> lines but I still get no display on the CRT (except the blinking
>> cursor). The TLB does give 1 beep when the power is turned on. (The same
>> thing my H19 does)
>> It's difficult to troubleshoot when the only thing visible is suppossed
>> to be on the CRT screen.
>>
>> I suppose it could be in the serial port interface.
>>
>> Anyone else have any ideas?
>>
>> Carroll
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I have a lot of manuals for the H89, but no spare parts. Robin suggested 
the ROMS. I can try to read them with my EPROM programmer.
Today, I'm going to try to see if I can see the 2msec clock interrupt 
being serviced.
Carroll
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