Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!caip!clyde!cbatt!cbosgd!ihnp4!drutx!druhi!wpc From: wpc@druhi.UUCP (ChristmasWP) Newsgroups: net.micro.atari16 Subject: ST crashing/resetting/disk errors Message-ID: <933@druhi.UUCP> Date: Thu, 28-Aug-86 19:37:31 EDT Article-I.D.: druhi.933 Posted: Thu Aug 28 19:37:31 1986 Date-Received: Sun, 31-Aug-86 05:03:50 EDT Organization: AT&T Information System Labs, Denver, Co Lines: 35 I have an early 520 ST with the new ROMS and the 1Meg upgrade. For the past month (since the ROM upgrade), the system has been crashing frequently. The crashes have come in the form of lockups, spontaneous resets and the disk suddenly appearing to have nothing on it. None of these things were permanently fatal; time, repowering or jarring the ST would temporarily fix the problem. Anyway, after much fooling around, I discovered that the voltage to my ICs was low (about 4.8 volts). I assume the extra bank of RAMs and extra ROMS (it was shipped with just the two) caused excessive current drain. In poking around, I noticed there was a choke in the path of the 5 volts that was not in the developer's kit schematics (L29 or L39 I think). This choke had a DC resistance of about 1/2 ohm and with my system had a voltage drop of about .4 volts under load. My current fix to the problem was to place another choke (of high AC impedence and about 1/2 ohm DC impedence) in parallel with the first. This reduced the DC drop across the inductor and raised my IC voltages to 5.0 volts. The questions- Do all STs have this inductor? What's it for? Any idea of what it's value is supposed to be (both DC and AC impedance)? Am I effecting anything else by changing the value of this inductor? Is my problem really a low voltage coming in from my power supply (I have the older style power supply), or is it that inductor? The system has behaved much better since I made the change, but I'd love to know if there's a better/safer fix! Thanks! Walt Christmas AT&T Denver ...!druhi!wpc