It sounds to me like the CPU board is functional, at least enough to send a BEL character to the terminal board (second beep). Also, the terminal board seems to be functioning enough to respond to the BEL.
Maybe try depressing the OFFLINE button and confirm that you can
type characters and see them on the screen. Be sure you return the
OFFLINE button to the "up" position again. (confirms terminal
board is functioning)
Then maybe check your CPU board dipswitches to make sure that auto-boot is not selected. I'm not sure if that by-passes the normal prompt and goes straight to trying to boot.
Otherwise, maybe the monitor ROM (or H17 floppy ROM) is
bad/corrupted. You might need to burn new copies of those. You
could also have bad RAM that prevents the monitor from getting
started.
It's certainly possible that more tantalums have blown, so there could be some more-subtle failure preventing the monitor from getting to the part where it displays the prompt. Also, check what version of the monitor ROM you have.
That's my 2 cents, adjusted for inflation.
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I’ve seen “~” like that on power on. I assume it’s junk received by the UART. What’s displaying the on screen clock? Is there a built in clock of some sort?
If you don’t see anything with “OFF LINE” depressed that’s indicative of a problem in the terminal function – it should echo back what you type.
I’ve never done the RAM tests . are those on screen displays? If so then clearly the computer and terminal ARE talking?
From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Conner Burns
Sent: Sunday, December 27, 2020 6:44 PM
To: SEBHC <se...@googlegroups.com>
Subject: Re: [sebhc] H89-A Beeps Twice, no screen
I've made headway! The CRT now displays the image below at boot. It can boot into RAM test from dip switch, and passes those fine. The odd star thing doesn't blink, but the cursor does. No characters show on screen with or without offline depressed, and the only thing that effects this screen is pressing multiple keys and the space bar (think desperate keyboard mash) will reset the timer and get rid of the odd star thing in the corner. The cursor still blinks.
Any ideas? Bad character ROM?
On Friday, November 27, 2020 at 3:19:14 PM UTC-8 Joe Travis N6YPC wrote:
If you get 2 beeps at power up, it is very likely the CPU & TLB (Terminal Logic Board) are both fine. Double check all cable connections to the video board.
Turn up the brightness control on the back. Do you see a raster of any kind? No: check the video cabling from the TLB to the brightness pot and to the video board. Still nothing, check voltages following the troubleshooting guide in the manual.
Good luck,
Joe
On Fri, Nov 27, 2020, 5:31 PM Conner Burns <poodb...@gmail.com> wrote:
Hello all,
My rainstorm dumpster H89-A won't show anything on the screen. The first smoke test I did showed a very faint pattern ( screen all one character, looks like a memory error?), then died once the tantalum at C103 blew. The heater still glows, faintly. I have replaced C103 and C102 with 1uF, 50v tants. Now, I flip it on and I get the fan and two beeps, faint heater glow that doesn't change with the brightness knob around back, and no picture at all. The PSU seems to be outputting all the correct voltages, within limits according to my multimeter.
Any advice?
Thank you,
Conner
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Clearly the Terminal board works and the CPU can talk to it.
My guess is a bad keyboard or keyboard encoder. Failure is not uncommon. A while back (2012) Mark Garlanger found a source for the encoder and coordinated a group order. Not sure if that’s still available out there.
https://groups.google.com/g/sebhc/c/WAGZnW3_4R0/m/rzvxy0F0z0kJ
might be easier to locate a junker H19 and swap parts, or maybe someone here can help.
From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Conner Burns
Sent: Sunday, December 27, 2020 9:03 PM
To: SEBHC <se...@googlegroups.com>
Subject: Re: [sebhc] H89-A Beeps Twice, no screen
That 'clock' is just a timer counting up from boot. I assume the TLB and CPU board are working, possibly an IC issue...
The RAM tests are pictured below. It's triggered at boot by switching SW501 dip switch #5 to 0.
I also narrowed down the key mash that resets the timer, it's 'J K N M SPACE' all at once.

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Hi Conner,
Based on what I have read on this between you and Glenn and by looking at the image of the screen, I tend to believe that Joseph Travis may be on to something in thinking you may have a modification to add the Watzman ROM.
Sent from Mail for Windows 10
From: Conner Burns
Sent: Sunday, December 27, 2020 9:02 PM
To: SEBHC
Subject: Re: [sebhc] H89-A Beeps Twice, no screen
That 'clock' is just a timer counting up from boot. I assume the TLB and CPU board are working, possibly an IC issue...
The RAM tests are pictured below. It's triggered at boot by switching SW501 dip switch #5 to 0.
I also narrowed down the key mash that resets the timer, it's 'J K N M SPACE' all at once.
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Conner: can you say more about how you found this machine? Always interesting to hear the “rescue” stories!
From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Conner Burns
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On Dec 28, 2020, at 11:33 AM, Conner Burns <poodb...@gmail.com> wrote:
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On Dec 29, 2020, at 5:04 AM, Glenn Roberts <glenn.f...@gmail.com> wrote:
If Shift-RESET doesn’t do anything that would seem to point to a mechanical problem with the keyboard since those keys are directly hard wired into Z80 reset logic gates.
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Sorry missed that… ☹
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