My KIM-1 seems dead :S
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Liu GN
Nov 22, 2021, 11:30:57 AM11/22/21
to PAL 6502 computer
Hello community,
Today, I took out my KIM-1 to test the new gadget on PAL-1, I sadly find
that my KIM-1 cannot lit up its display.
I checked all the steps in the KIM-1 user manual appendix C "display not
lit", the power supply is 4.85V (later, I changed the power supply to a
bench DC power supply), KB/TTY jumper is set to KB, decoder enabled,
keypad is nice and clean, reset circuit is working normally, phase 2
clock is correct.
Then I found this post on vcfed.org
(https://www.vcfed.org/forum/forum/genres/commodore/43708-rev-e-kim-1-appears-dead),
I followed reply #8 by daver2
(https://www.vcfed.org/forum/forum/genres/commodore/43708-rev-e-kim-1-appears-dead?p=532317#post532317),
I checked the U1 (6502) and U16 (7404)'s clock signal, all seems normal.
Also the address lines are working.
When I do the display section test, all LEDs are on working condition,
but the segment illuminate is not right I feel. The LED lights up all
segments (shows digit 8) when I jumped the base pin of transistor to
ground, the U17 (7406) pins are no effect to the LED content, all six
LED displays always show 8 (all segment lit) when the transistor's base
pin jumped to ground (with 1K resistor).
I think this is the most unwanted situation now, the problem may come
from 6530. I checked some pins on 6530-002 (U2), the signal is abnormal
(in my opinion), and I measured the 6530-003, the signals are very
similar with 6530-002, are they both failed...? I compared with the
6532's pins on the PAL-1, the photo and screenshots are attached.
Moreover, I tried to connect by TTY, the terminal also cannot show the
KIM prompt, just a long messy code received.
Can anyone help me to identify this symptom!
Thanks!
Liu
Today, I took out my KIM-1 to test the new gadget on PAL-1, I sadly find
that my KIM-1 cannot lit up its display.
I checked all the steps in the KIM-1 user manual appendix C "display not
lit", the power supply is 4.85V (later, I changed the power supply to a
bench DC power supply), KB/TTY jumper is set to KB, decoder enabled,
keypad is nice and clean, reset circuit is working normally, phase 2
clock is correct.
Then I found this post on vcfed.org
(https://www.vcfed.org/forum/forum/genres/commodore/43708-rev-e-kim-1-appears-dead),
I followed reply #8 by daver2
(https://www.vcfed.org/forum/forum/genres/commodore/43708-rev-e-kim-1-appears-dead?p=532317#post532317),
I checked the U1 (6502) and U16 (7404)'s clock signal, all seems normal.
Also the address lines are working.
When I do the display section test, all LEDs are on working condition,
but the segment illuminate is not right I feel. The LED lights up all
segments (shows digit 8) when I jumped the base pin of transistor to
ground, the U17 (7406) pins are no effect to the LED content, all six
LED displays always show 8 (all segment lit) when the transistor's base
pin jumped to ground (with 1K resistor).
I think this is the most unwanted situation now, the problem may come
from 6530. I checked some pins on 6530-002 (U2), the signal is abnormal
(in my opinion), and I measured the 6530-003, the signals are very
similar with 6530-002, are they both failed...? I compared with the
6532's pins on the PAL-1, the photo and screenshots are attached.
Moreover, I tried to connect by TTY, the terminal also cannot show the
KIM prompt, just a long messy code received.
Can anyone help me to identify this symptom!
Thanks!
Liu
Hans Otten
Nov 22, 2021, 12:57:13 PM11/22/21
to PAL 6502 computer
Feeling sorry for you and the KIM-1! Dead 6530 I am afraid, often the cause. So TTY will also not work.
Can be repaired with 6532 and ROM, though that is a bit ugly.
But I have seen reports of RAM or 6502 failure.
Dwight Elvey made a 6530 replacement board that is small enough to not look too big compared to for example the bigger Corsham print.
Dwight Elvey also did a test cartridge, that does check without requiring an operational 6530 or RAM.
It does take over the whole KIM-1 as ROM, dip switches select tests.
It does take over the whole KIM-1 as ROM, dip switches select tests.
I have from Dwight received the rather complete design of that cartridge (EPROM and some logic IC's) and the ROM contents. Not published yet, since the circuit diagram is lost and I want to recreate that.
But I can send you now what I have, so you better see what is wrong, 6502, 6530, RAM.
Hans
Hendrik-Jan Megens
Nov 22, 2021, 3:34:38 PM11/22/21
to PAL 6502 computer
Sorry to hear about your KIM-1, Liu. It's the bane of retrocomputing - our beloved machines dying inevitably at one point.
Keeping the hardware alive is challenging, so again, many thanks for creating such a wonderful clone. Your KIM-1 may be ailing, but you are working hard to keep the KIM-1 spirit alive!
For myself, I wouldn't know what I would do - desolder the 6530 and replace it with a 6532-based prosthetic? How much to fix, up to the point that the machine loses too many of it's original parts is a question I have for some of my old machines generally. It is one reason I'm so excited about clones and remakes. My original Micro-professor is not doing very well, for instance (admittedly a much less iconic machine than the KIM-1). But now that I have built a remake that's fine. I can hack that thing however I like. An original KIM-1 I wouldn't even buy (not at the prices I usually see on eBay) - I would be too afraid to even apply power to it! In stead I bought a nice KIM-1 clone from Dave Williams a while back (honestly, I'm having tons more fun with my PAL-1 because I built that one myself!).
Hoping your KIM-1 will make a miraculous recovery!
Hendrik-Jan
Liu GN
Nov 22, 2021, 8:58:09 PM11/22/21
to pal...@googlegroups.com
Hi Hans,
I got your email about Dwight Elvey's test cartridge, you're the big
helper, thank you!
This feeling is really a pity. My only and most iconic 6502 historical
piece, now cannot work. This KIM-1 is the reason I try to build the
PAL-1 replica. I will try to figure out the problem, but I think I might
not fix it without vintage part, at least for now.
Best,
Liu
> Then I found this post on vcfed.org <http://vcfed.org>
> (https://www.vcfed.org/forum/forum/genres/commodore/43708-rev-e-kim-1-appears-dead
> <https://www.vcfed.org/forum/forum/genres/commodore/43708-rev-e-kim-1-appears-dead>),
> You received this message because you are subscribed to the Google
> Groups "PAL 6502 computer" group.
> To unsubscribe from this group and stop receiving emails from it, send
> an email to pal6502+u...@googlegroups.com
> <mailto:pal6502+u...@googlegroups.com>.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/pal6502/b6d53bdb-f442-49ee-9c12-a2a814a2a454n%40googlegroups.com
> <https://groups.google.com/d/msgid/pal6502/b6d53bdb-f442-49ee-9c12-a2a814a2a454n%40googlegroups.com?utm_medium=email&utm_source=footer>.
> For more options, visit https://groups.google.com/d/optout
> <https://groups.google.com/d/optout>.
I got your email about Dwight Elvey's test cartridge, you're the big
helper, thank you!
This feeling is really a pity. My only and most iconic 6502 historical
piece, now cannot work. This KIM-1 is the reason I try to build the
PAL-1 replica. I will try to figure out the problem, but I think I might
not fix it without vintage part, at least for now.
Best,
Liu
> (https://www.vcfed.org/forum/forum/genres/commodore/43708-rev-e-kim-1-appears-dead
> <https://www.vcfed.org/forum/forum/genres/commodore/43708-rev-e-kim-1-appears-dead>),
>
> I followed reply #8 by daver2
> (https://www.vcfed.org/forum/forum/genres/commodore/43708-rev-e-kim-1-appears-dead?p=532317#post532317
> <https://www.vcfed.org/forum/forum/genres/commodore/43708-rev-e-kim-1-appears-dead?p=532317#post532317>),
> I followed reply #8 by daver2
> (https://www.vcfed.org/forum/forum/genres/commodore/43708-rev-e-kim-1-appears-dead?p=532317#post532317
>
> I checked the U1 (6502) and U16 (7404)'s clock signal, all seems
> normal.
> Also the address lines are working.
>
> When I do the display section test, all LEDs are on working condition,
> but the segment illuminate is not right I feel. The LED lights up all
> segments (shows digit 8) when I jumped the base pin of transistor to
> ground, the U17 (7406) pins are no effect to the LED content, all six
> LED displays always show 8 (all segment lit) when the transistor's base
> pin jumped to ground (with 1K resistor).
>
> I think this is the most unwanted situation now, the problem may come
> from 6530. I checked some pins on 6530-002 (U2), the signal is abnormal
> (in my opinion), and I measured the 6530-003, the signals are very
> similar with 6530-002, are they both failed...? I compared with the
> 6532's pins on the PAL-1, the photo and screenshots are attached.
>
> Moreover, I tried to connect by TTY, the terminal also cannot show the
> KIM prompt, just a long messy code received.
>
> Can anyone help me to identify this symptom!
>
> Thanks!
> Liu
>
> --
> I checked the U1 (6502) and U16 (7404)'s clock signal, all seems
> normal.
> Also the address lines are working.
>
> When I do the display section test, all LEDs are on working condition,
> but the segment illuminate is not right I feel. The LED lights up all
> segments (shows digit 8) when I jumped the base pin of transistor to
> ground, the U17 (7406) pins are no effect to the LED content, all six
> LED displays always show 8 (all segment lit) when the transistor's base
> pin jumped to ground (with 1K resistor).
>
> I think this is the most unwanted situation now, the problem may come
> from 6530. I checked some pins on 6530-002 (U2), the signal is abnormal
> (in my opinion), and I measured the 6530-003, the signals are very
> similar with 6530-002, are they both failed...? I compared with the
> 6532's pins on the PAL-1, the photo and screenshots are attached.
>
> Moreover, I tried to connect by TTY, the terminal also cannot show the
> KIM prompt, just a long messy code received.
>
> Can anyone help me to identify this symptom!
>
> Thanks!
> Liu
>
> You received this message because you are subscribed to the Google
> Groups "PAL 6502 computer" group.
> To unsubscribe from this group and stop receiving emails from it, send
> an email to pal6502+u...@googlegroups.com
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> To view this discussion on the web visit
> https://groups.google.com/d/msgid/pal6502/b6d53bdb-f442-49ee-9c12-a2a814a2a454n%40googlegroups.com
> <https://groups.google.com/d/msgid/pal6502/b6d53bdb-f442-49ee-9c12-a2a814a2a454n%40googlegroups.com?utm_medium=email&utm_source=footer>.
> For more options, visit https://groups.google.com/d/optout
> <https://groups.google.com/d/optout>.
Liu GN
Nov 22, 2021, 9:15:18 PM11/22/21
to pal...@googlegroups.com
Hi Hendrik-Jan,
Thank you! I bought this KIM-1 from ebay about two years ago. After
contributing a lot of page visits to the Hans retro site years, I
finally won the bid of this original KIM-1 at a reasonable price (still
very expensive), I felt very lucky after received the package safely
from US. Now, I'm sad, at least for days.
I also have a Micro-Professor, it's a MPF-1 Plus, I checked it
immediately after I found my KIM-1 is dead yesterday. Fortunately, the
MPF is still working! Micro-Professor is a well built machine in my
opinion, it is younger than KIM-1, so it will be more stable then KIM-1.
I will try to find out the problem of my KIM-1, but I may not try to fix
it until I can find vintage part for it or I can acquire another KIM-1
(in reasonable price, the buy it now price on ebay is insane). I will
stay with PAL-1 more time when the KIM-1 is ailing, I suddenly felt
lucky that I built the PAL-1 kit. Just like you said, my hand is shaking
every time I power on the KIM-1, that's for real.
Best,
Liu
> <https://groups.google.com/d/msgid/pal6502/be86489e-e938-4ee5-a257-eb2b79e907ben%40googlegroups.com?utm_medium=email&utm_source=footer>.
Thank you! I bought this KIM-1 from ebay about two years ago. After
contributing a lot of page visits to the Hans retro site years, I
finally won the bid of this original KIM-1 at a reasonable price (still
very expensive), I felt very lucky after received the package safely
from US. Now, I'm sad, at least for days.
I also have a Micro-Professor, it's a MPF-1 Plus, I checked it
immediately after I found my KIM-1 is dead yesterday. Fortunately, the
MPF is still working! Micro-Professor is a well built machine in my
opinion, it is younger than KIM-1, so it will be more stable then KIM-1.
I will try to find out the problem of my KIM-1, but I may not try to fix
it until I can find vintage part for it or I can acquire another KIM-1
(in reasonable price, the buy it now price on ebay is insane). I will
stay with PAL-1 more time when the KIM-1 is ailing, I suddenly felt
lucky that I built the PAL-1 kit. Just like you said, my hand is shaking
every time I power on the KIM-1, that's for real.
Best,
Liu
> Then I found this post on vcfed.org <http://vcfed.org>
> (https://www.vcfed.org/forum/forum/genres/commodore/43708-rev-e-kim-1-appears-dead
> <https://www.vcfed.org/forum/forum/genres/commodore/43708-rev-e-kim-1-appears-dead>),
>
> (https://www.vcfed.org/forum/forum/genres/commodore/43708-rev-e-kim-1-appears-dead
> <https://www.vcfed.org/forum/forum/genres/commodore/43708-rev-e-kim-1-appears-dead>),
>
> I followed reply #8 by daver2
> (https://www.vcfed.org/forum/forum/genres/commodore/43708-rev-e-kim-1-appears-dead?p=532317#post532317
> <https://www.vcfed.org/forum/forum/genres/commodore/43708-rev-e-kim-1-appears-dead?p=532317#post532317>),
> (https://www.vcfed.org/forum/forum/genres/commodore/43708-rev-e-kim-1-appears-dead?p=532317#post532317
> --
> You received this message because you are subscribed to the Google
> Groups "PAL 6502 computer" group.
> To unsubscribe from this group and stop receiving emails from it, send
> an email to pal6502+u...@googlegroups.com
> <mailto:pal6502+u...@googlegroups.com>.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/pal6502/be86489e-e938-4ee5-a257-eb2b79e907ben%40googlegroups.com
> You received this message because you are subscribed to the Google
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> To unsubscribe from this group and stop receiving emails from it, send
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> <mailto:pal6502+u...@googlegroups.com>.
> To view this discussion on the web visit
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Hans Otten
Nov 23, 2021, 4:27:47 AM11/23/21
to PAL 6502 computer
From what I read on vcfed.org forum on Dwight Elveys replacement board, the RAMS are more often the problem, so that maybe a less difficult and more authentic repair.
Lets hope the diagnostic board can help you.
Liu GN
Nov 23, 2021, 7:14:23 AM11/23/21
to pal...@googlegroups.com
A NEW HOPE :)
> <http://vcfed.org <http://vcfed.org>>
> <https://groups.google.com/d/msgid/pal6502/be86489e-e938-4ee5-a257-eb2b79e907ben%40googlegroups.com?utm_medium=email&utm_source=footer
> <https://groups.google.com/d/msgid/pal6502/c0371cdb-f5c3-487c-8636-f3c0ccdb4da7n%40googlegroups.com?utm_medium=email&utm_source=footer>.
> <https://groups.google.com/d/msgid/pal6502/be86489e-e938-4ee5-a257-eb2b79e907ben%40googlegroups.com?utm_medium=email&utm_source=footer>>.
>
> > For more options, visit https://groups.google.com/d/optout
> <https://groups.google.com/d/optout>
> > <https://groups.google.com/d/optout
> <https://groups.google.com/d/optout>>.
>
>
> > For more options, visit https://groups.google.com/d/optout
> <https://groups.google.com/d/optout>
> > <https://groups.google.com/d/optout
> <https://groups.google.com/d/optout>>.
>
> --
> You received this message because you are subscribed to the Google
> Groups "PAL 6502 computer" group.
> To unsubscribe from this group and stop receiving emails from it, send
> an email to pal6502+u...@googlegroups.com
> <mailto:pal6502+u...@googlegroups.com>.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/pal6502/c0371cdb-f5c3-487c-8636-f3c0ccdb4da7n%40googlegroups.com
> You received this message because you are subscribed to the Google
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> <mailto:pal6502+u...@googlegroups.com>.
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GN L
Dec 7, 2021, 7:46:14 AM12/7/21
to PAL 6502 computer
Very happy to tell that my KIM-1 is back to live!!!
After I sent my KIM-1 seems dead to this group, Hans sent me a very useful information, the KIM-1 debug board (now the complete data of the debug board is online at http://retro.hansotten.nl/6502-sbc/kim-1-manuals-and-software/kim-1-diagnostic-board/ ).
I built the debug board, test my KIM-1 step by step. The processor on my KIM-1 board is OK, next step is the RAM test, I got an error bit (U6) of the RAM subsystem. I replaced the possibly failed RAM chip with a NOS one I bought a few days ago, but the error remains. This means the error may be on the buffer chip (U13).
When I waiting the buffer chips, I modified a RAM test program, a simple and useful Arduino program, I can confirm that the RAM chip I desoldered from KIM-1 is functioning normally with Arduino test program.
Today, I received the buffer chips, I desolder the possibly damaged 74125 from KIM-1, and test it with TL866, it is broken. After replacing the failed 74125, KIM-1 passed the RAM test of the debug board: eight long green flash!
Connect my bench power to KIM-1, hit RS, the dim red led displays show me 44d0 44, its back to live!
Thanks HJM, Nils, Hans and everyone who read this message.
Very happy day :)
Attached some photos for reference.
Thanks,
Liu
To unsubscribe from this group and stop receiving emails from it, send an email to pal6502+u...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/pal6502/c0371cdb-f5c3-487c-8636-f3c0ccdb4da7n%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
Best,
Liu
Liu
Neil Andretti
Dec 7, 2021, 9:27:08 AM12/7/21
to PAL 6502 computer
Great news!
I feel so happy for you.
And you even have a new product for your tindie shop (even if the target group is "managable")
🎆
I raise my glas
Nils
GN L
Dec 7, 2021, 10:19:20 AM12/7/21
to Neil Andretti, PAL 6502 computer
Right, I can resume doing the comparison between KIM-1 and PAL-1 in the future (if needed).
Yes, the ugly chips version PAL-1 kit.
I did a “two days” chip check, and currently have 5 PCBs without chip set, so I combined these for 5 sets of ugly chip PAL-1 for someone who need a lower price kit.
Liu
> On Dec 7, 2021, at 10:27 PM, 'Neil Andretti' via PAL 6502 computer <pal...@googlegroups.com> wrote:
>
> Great news!
> I feel so happy for you.
> And you even have a new product for your tindie shop (even if the target group is "managable")
> 🎆
> I raise my glas
> Nils
> liuga...@gmail.com schrieb am Dienstag, 7. Dezember 2021 um 13:46:14 UTC+1:
> Very happy to tell that my KIM-1 is back to live!!!
>
> After I sent my KIM-1 seems dead to this group, Hans sent me a very useful information, the KIM-1 debug board (now the complete data of the debug board is online at http://retro.hansotten.nl/6502-sbc/kim-1-manuals-and-software/kim-1-diagnostic-board/ ).
>
> I built the debug board, test my KIM-1 step by step. The processor on my KIM-1 board is OK, next step is the RAM test, I got an error bit (U6) of the RAM subsystem. I replaced the possibly failed RAM chip with a NOS one I bought a few days ago, but the error remains. This means the error may be on the buffer chip (U13).
>
> When I waiting the buffer chips, I modified a RAM test program, a simple and useful Arduino program, I can confirm that the RAM chip I desoldered from KIM-1 is functioning normally with Arduino test program.
>
> Today, I received the buffer chips, I desolder the possibly damaged 74125 from KIM-1, and test it with TL866, it is broken. After replacing the failed 74125, KIM-1 passed the RAM test of the debug board: eight long green flash!
>
> Connect my bench power to KIM-1, hit RS, the dim red led displays show me 44d0 44, its back to live!
>
> Thanks HJM, Nils, Hans and everyone who read this message.
> Very happy day :)
>
> Attached some photos for reference.
>
>
> To view this discussion on the web visit https://groups.google.com/d/msgid/pal6502/a264b991-8886-45a4-9636-74bded099512n%40googlegroups.com.
Yes, the ugly chips version PAL-1 kit.
I did a “two days” chip check, and currently have 5 PCBs without chip set, so I combined these for 5 sets of ugly chip PAL-1 for someone who need a lower price kit.
Liu
> On Dec 7, 2021, at 10:27 PM, 'Neil Andretti' via PAL 6502 computer <pal...@googlegroups.com> wrote:
>
> Great news!
> I feel so happy for you.
> And you even have a new product for your tindie shop (even if the target group is "managable")
> 🎆
> I raise my glas
> Nils
> liuga...@gmail.com schrieb am Dienstag, 7. Dezember 2021 um 13:46:14 UTC+1:
> Very happy to tell that my KIM-1 is back to live!!!
>
> After I sent my KIM-1 seems dead to this group, Hans sent me a very useful information, the KIM-1 debug board (now the complete data of the debug board is online at http://retro.hansotten.nl/6502-sbc/kim-1-manuals-and-software/kim-1-diagnostic-board/ ).
>
> I built the debug board, test my KIM-1 step by step. The processor on my KIM-1 board is OK, next step is the RAM test, I got an error bit (U6) of the RAM subsystem. I replaced the possibly failed RAM chip with a NOS one I bought a few days ago, but the error remains. This means the error may be on the buffer chip (U13).
>
> When I waiting the buffer chips, I modified a RAM test program, a simple and useful Arduino program, I can confirm that the RAM chip I desoldered from KIM-1 is functioning normally with Arduino test program.
>
> Today, I received the buffer chips, I desolder the possibly damaged 74125 from KIM-1, and test it with TL866, it is broken. After replacing the failed 74125, KIM-1 passed the RAM test of the debug board: eight long green flash!
>
> Connect my bench power to KIM-1, hit RS, the dim red led displays show me 44d0 44, its back to live!
>
> Thanks HJM, Nils, Hans and everyone who read this message.
> Very happy day :)
>
> Attached some photos for reference.
>
>
Hendrik-Jan Megens
Dec 7, 2021, 12:56:10 PM12/7/21
to PAL 6502 computer
Excellent operation, surgeon Liu! The KIM lives!
Thanks also for sharing, very interesting to see how the diagnostics and repairs were carried out!
May your KIM stay healthy for a long time to come!
Cheers,
Hendrik-Jan
GN L
Dec 7, 2021, 8:08:19 PM12/7/21
to Hendrik-Jan Megens, PAL 6502 computer
May the force be with KIM-1 ;)
> To view this discussion on the web visit https://groups.google.com/d/msgid/pal6502/e709c681-2c12-470f-bc2f-acf1e83e47bfn%40googlegroups.com.
John Kennedy
Dec 7, 2021, 8:38:40 PM12/7/21
to PAL 6502 computer
Congrats! How satisfying!
GN L
Dec 7, 2021, 9:33:30 PM12/7/21
to John Kennedy, PAL 6502 computer
Thanks! It is satisfying, brighten my day!
> On Dec 8, 2021, at 9:38 AM, John Kennedy <johntk...@gmail.com> wrote:
>
>
> Congrats! How satisfying!
>
> On Tuesday, December 7, 2021 at 4:46:14 AM UTC-8 liuga...@gmail.comwrote:
> Very happy to tell that my KIM-1 is back to live!!!
>
> After I sent my KIM-1 seems dead to this group, Hans sent me a very useful information, the KIM-1 debug board (now the complete data of the debug board is online at http://retro.hansotten.nl/6502-sbc/kim-1-manuals-and-software/kim-1-diagnostic-board/ ).
>
> I built the debug board, test my KIM-1 step by step. The processor on my KIM-1 board is OK, next step is the RAM test, I got an error bit (U6) of the RAM subsystem. I replaced the possibly failed RAM chip with a NOS one I bought a few days ago, but the error remains. This means the error may be on the buffer chip (U13).
>
> When I waiting the buffer chips, I modified a RAM test program, a simple and useful Arduino program, I can confirm that the RAM chip I desoldered from KIM-1 is functioning normally with Arduino test program.
>
> Today, I received the buffer chips, I desolder the possibly damaged 74125 from KIM-1, and test it with TL866, it is broken. After replacing the failed 74125, KIM-1 passed the RAM test of the debug board: eight long green flash!
>
> Connect my bench power to KIM-1, hit RS, the dim red led displays show me 44d0 44, its back to live!
>
> Thanks HJM, Nils, Hans and everyone who read this message.
> Very happy day :)
>
> Attached some photos for reference.
>
>
> To view this discussion on the web visit https://groups.google.com/d/msgid/pal6502/7c801f24-b4c5-4594-bc66-70a6e0f76634n%40googlegroups.com.
> On Dec 8, 2021, at 9:38 AM, John Kennedy <johntk...@gmail.com> wrote:
>
>
> Congrats! How satisfying!
>
> On Tuesday, December 7, 2021 at 4:46:14 AM UTC-8 liuga...@gmail.comwrote:
> Very happy to tell that my KIM-1 is back to live!!!
>
> After I sent my KIM-1 seems dead to this group, Hans sent me a very useful information, the KIM-1 debug board (now the complete data of the debug board is online at http://retro.hansotten.nl/6502-sbc/kim-1-manuals-and-software/kim-1-diagnostic-board/ ).
>
> I built the debug board, test my KIM-1 step by step. The processor on my KIM-1 board is OK, next step is the RAM test, I got an error bit (U6) of the RAM subsystem. I replaced the possibly failed RAM chip with a NOS one I bought a few days ago, but the error remains. This means the error may be on the buffer chip (U13).
>
> When I waiting the buffer chips, I modified a RAM test program, a simple and useful Arduino program, I can confirm that the RAM chip I desoldered from KIM-1 is functioning normally with Arduino test program.
>
> Today, I received the buffer chips, I desolder the possibly damaged 74125 from KIM-1, and test it with TL866, it is broken. After replacing the failed 74125, KIM-1 passed the RAM test of the debug board: eight long green flash!
>
> Connect my bench power to KIM-1, hit RS, the dim red led displays show me 44d0 44, its back to live!
>
> Thanks HJM, Nils, Hans and everyone who read this message.
> Very happy day :)
>
> Attached some photos for reference.
>
>
Jeff Nay
Jul 21, 2022, 6:01:48 AM7/21/22
to PAL 6502 computer
My KIM-1 recently stopped working and I could use some help. All signals look pretty good. I heard about a diag board that you were able to build. Can I purchase that board somewhere?
Like you, I think my problem might be in the memory somewhere.
Jeff Nay
Jul 21, 2022, 6:04:00 AM7/21/22
to PAL 6502 computer
Hey Hans,
My KIM-1 recently stopped working. How do I get one of Dwight's Diag boards?
GN L
Jul 21, 2022, 6:23:05 AM7/21/22
to Jeff Nay, PAL 6502 computer
Hi Jeff,
Sorry for hear this.
I’ll try to find out the PCB I made before, I remember I had some left over somewhere.
> To view this discussion on the web visit https://groups.google.com/d/msgid/pal6502/eaf64c56-d472-41ec-881f-cab095941b67n%40googlegroups.com.
> For more options, visit https://groups.google.com/d/optout.
Best,
Liu
Sorry for hear this.
I’ll try to find out the PCB I made before, I remember I had some left over somewhere.
> --
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> For more options, visit https://groups.google.com/d/optout.
Best,
Liu
Jeff Nay
Jul 21, 2022, 6:34:35 AM7/21/22
to PAL 6502 computer
I would love to go over some signal comparisons. I thought my U4 74LS145 decoder signals looked strange.
Using logic probe this is what I saw. Logic probe probably not the best test.
(U4) 74LS145
Input A (AB10) High
Input B (AB11) Blinking (???) Shouldn't Output 2 be blinking as well?
Input C (AB12) High
Input D = Low
Output 0-5 & 7 = High
Output 6 = Blinking (Shouldn’t Input C and B be blinking? ) Isn't Output 6 basically K6? (6530-003)
Again, using logic probe, maybe not the best.
Although I do suspect a memory problem of some sort. Thinking about piggy backing some 2102s, not sure where to start.
On Monday, November 22, 2021 at 11:30:57 AM UTC-5 liuga...@gmail.com wrote:
Jeff Nay
Jul 21, 2022, 8:55:02 AM7/21/22
to PAL 6502 computer
Piggy backing all memory, did produce 1 7 segment display to light up.
.
Jeff Nay
Jul 21, 2022, 9:23:54 AM7/21/22
to PAL 6502 computer
This is what I call PFM (Pure F'n Magic)
After removing each piggy backed memory chip. The system appears to be working again !!! WHAT !!!
You can not make this stuff up... :o)
Will it stay working??? I hope so !!! I am a bit afraid to turn it off.
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