Re: CBM 610 troubleshooting

Christian,

That is very handy to know! Thanks! I have a P500 that doesn't start up and the one non-socketed chip is a 6525. I tested the others and they are ok. I kinda suspected it anyway but it's good to see probable confirmation. I guess I'll be de-soldering that chip :-)

Steve



>________________________________
> From: Christian Dirks <Toast_r@IdeaLine.info>
>To: cbm-hackers@musoftware.de 
>Sent: Thursday, January 24, 2013 4:40:41 PM
>Subject: Re: CBM 610 troubleshooting
> 
>The IEEE bus handshake lines are controlled by the 6525 at U2,
>only the data lines are controlled by the 6526 at U1.
>So U2 may be bad.
>
>I did some tests on a working CBM610:
>It will start up with the PLA removed, but it will not be useable, since there will be no DRAM accessible.
>It will start up with the 6526 removed. (No IEEE bus)
>It will start up with the 6551 removed. (No RS-232)
>It will start up with the SID removed. (No sound)
>It will start up with the 6845 removed. (No video)
>It will start up with the char-rom removed. (Video not readable)
>It will start up to the TIM monitor with the Basic ROMs removed.
>It will NOT start up with the 6525 at U28 removed.
>It SHOULD start up with the 6525 at U2 removed with no IEEE bus. Since this one is soldered in, I did not test it.
>Without the Basic ROMs and PLA, TIM will work fine in bank 15. CTRL-G will ring the bell. The IEEE bus will work. (.L "$",08)
>
>Christian
>
>Am 24.01.2013 19:12, schrieb Michał Pleban:
>> Hello!
>> 
>> Anders Carlsson wrote:
>> 
>>> Unfortunately, replacing the 6526 with a known good chip didn't change
>>> anything. Also, I tried the 6509 from the 610 into the 710, and the
>>> latter boots to Basic like it should. This suggests that both CIA and
>>> CPU are good in the 610, and the problem is to be found elsewhere. Too
>>> bad the 6525's aren't socketed, as I acquired a few from Rob before.
>> That's too bad. If you don't have an oscilloscope and the CIA chip is
>> not broken, I guess there's not much you can do except shipping it to me
>> (I do have an oscilloscope) :-P
>> 
>> Regards,
>> Michau.
>> 
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>
>-- Christian Dirks
>Toast_r@Idealine.info
>
>
>
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