Phantom drive?
in [Commodore]
|
Prev: Starcraft for C64
Next: Breadbox vs C64c - reliability?
From: Paul Förster on 5 Nov 2009 06:04 Hi, .... I have a strange problem I never encountered before. With my C64C, I do LOAD"$",8 and it says SEARCHING FOR $, though no drive is connected. It sees a phantom drive though the DEVICE NOT PRESENT error should occur -- and does with other C64s. I already checked CIA2, U21, U22 and U23 and replaced them with known good parts. The symptom remains. I don't need to mention that the C64C doesn't access a connected drive anymore (it used to work)... I've checked with known good drives and they are good for other C64Cs. So the drive is definitily not the culprit. I also checked Ray Carlsen's infos and the schematics (which brought me to U21-U23) but I'm stuck here. Any ideas? Some resistor, capacitor or something? -- cul8er Paul paul.foerster(a)gmx.net
From: Paul Förster on 5 Nov 2009 06:28 Hi, On 2009-11-05 12:04:46 +0100, Paul F�rster <paul.foerster(a)gmx.net> said: > I already checked CIA2, U21, U22 and U23 and replaced them with known > good parts. The symptom remains. .... oops! That was meant to be CIA2, U21, U22 and U3, not U23. Sorry. -- cul8er Paul paul.foerster(a)gmx.net
From: Ruud on 5 Nov 2009 07:11 Hallo Paul, > ... oops! That was meant to be CIA2, U21, U22 and U3, not U23. Sorry. This error normally occurs when the 7406 and/or 74LS14 inside a 1541 are broken and short circuit the Data and/or Clock line. But with no 1541 attached, it cannot be them. IMHO the same can happen in the C64. So please check the 7406 inside your C64. But knowing you have been soldering, check with an Ohm meter if you haven't unwantedly shortcircuit someting with a drop of solder. -- ___ / __|__ / / |_/ Groetjes, Ruud \ \__|_\ \___| URL: Ruud.C64.org
From: Paul Förster on 5 Nov 2009 07:18 Hi Ruud, On 2009-11-05 13:11:47 +0100, Ruud <Ruud.Baltissen(a)apg.nl> said: > This error normally occurs when the 7406 and/or 74LS14 inside a 1541 > are broken and short circuit the Data and/or Clock line. But with no > 1541 attached, it cannot be them. IMHO the same can happen in the C64. > So please check the 7406 inside your C64. > > But knowing you have been soldering, check with an Ohm meter if you > haven't unwantedly shortcircuit someting with a drop of solder. .... I already checked a couple of times. And I've tried three different 7406 chips, to no avail. That's why I ask. -- cul8er Paul paul.foerster(a)gmx.net
From: Paul Förster on 5 Nov 2009 08:09
Hi Ruud, On 2009-11-05 13:11:47 +0100, Ruud <Ruud.Baltissen(a)apg.nl> said: > But knowing you have been soldering, check with an Ohm meter if you > haven't unwantedly shortcircuit someting with a drop of solder. .... ok, I've double checked *again*, all 14 pins of the chip. All of them connect where they are supposed to connect. There are no soldering drops or shorts of neighboring lines. All *seems* well, but something gotta be wrong here. -- cul8er Paul paul.foerster(a)gmx.net |