On 04/05/2016 06:11 PM, Rob Clarke wrote: > Hello gentlemen, > > While investigating 3 failed 1551 drives, I found that in two of them > both the 6523T and the 6525 in the drive were both defective. This I > could understand in the case of spikes, static, or careless hot-plugging > of the peripherals. But given a failure mode where one of the peripheral > chips fails due to old-age, are they likely to die shorting the I/O pin > to Vcc or ground, and if so, would it be likely to damage the I/O port > to which it's connected? The usual way to damage the 1551 is to plug or unplug the paddle while the computer and/or the 1551 is running. > Also, as both the 6525 in the 1551 and the 6523T in the paddle take > their power separately, and one obviously has to be powered on before > the other, is there any any specific risk with these chips receiving > logical high or low signals on their ports without power being applied? No, otherwise you'd have the same problem with a 1541 on the IEC-Bus-Signals. > (fixing the 1551 paddle I will necro post on the old 6523T replacement > thread) You can make a 6525A fit. Well... kinda. It will work, but it won't look pretty. Gerrit Message was sent through the cbm-hackers mailing listReceived on 2016-04-05 17:01:01
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