Re: Possible reorganisation of comp.sys.apple2 hierarchy

[sebugg@CS1.PRESBY.EDU (Stephen Buggie)]

This is NOT sent in reply to Patrick Sonnek's message, although I 
agree with mhim because I too have the computers for the "common
man," the IIe and IIc.

This is actually a request for technical advice on fixing the 
"disk use" indicator lamp on one of my IIc computers.  It is a 
small problem but IU trust rtthat others too feel aggravation when
a defective indicator lamp stares you in the face.

Hrere comes the nmessage out of my bugffer...........................
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                               TECHNICAL ADVICE SOUGHT
                            IIC "DISK USE" INDICATOR LAMP
                            =============================


       I have two identical "Unidisk IIc" computers; the middle of three
IIc models.  They can operate a unidisk 3.5" disk drive, but there is no
memory socket on the motherboard.  These are the white-cased computers
produced in 1986.

       I got one of the computers cheaply ($35) in as-is condition because
one RAM chip was faulty.  I replaced that chip and now the computer passes
all diagnostics (Nikrom Master Diagnostics IIc; Yo Yo Duck diagnostics,
the internal self-test diagnostics.

       The remaining problem is that the red "DISK IN USE" LED lamp does not
illuminate.  (The green lamp indicating "Power On" does work fine.) Tonight
I opened the IIc again to tinker with that lamp; it is annoying to face a
non-working indicator lamp when the rest of the computer works fine.

       I removed the faulty lamp with a very clean desoldering job.  The
voltage on the bad lamp circuit is only 1.4 v, while for the other (working)
LED lamp the voltage is 1.85 v.  On the bad circuit the voltage rises and falls
with the operation of the disk, suggesting that the control of the circuit is
normal.  But the red LED lamp DOES work when I touch both wires to the other
lamp's circuit.  I deduce then that the indicator lamp is good, but it requires
more than the 1.4 v supplied by the "disk use" circuit.  The voltage is
slightly low so the lamp does not illuminate.  [Yes, I know that LED lamps
have polarity, and I have tried the LED in either direction.]

       Can anyone advise me?  Can any other small lamp be substituted which
can operate on the 1.4 v available in its circuit?  Why would the voltage differ
in these two lamp circuits?????

       Thanks.

       Stephen Buggie,  410 Chestnut St., Clinton SC  29325
       sebugg