General Category > LisaList2
Lisa 2 started throwing Error 45
dmark:
--- Quote from: sigma7 on May 11, 2022, 09:21:53 pm ---
--- Quote from: dmark on May 11, 2022, 06:28:30 pm ---Now, the 5V rails look fine... But the 12V rails seem way out of whack on the I/O board. +7V and -17.5V respectively. :o
Which is weird, because before I measured a clean +12V on the Lite Adapter board, so I assumed that the same rail was ok elsewhere!
Just to make sure, I pulled out the Lite Adapter board again and measured on the floppy header, and am still getting a very neat +12V there.
So... at least I have a concrete issue to track down. It's almost as if 5V is being subtracted (or negative voltage added I guess) to the 12V rails!?
--- End quote ---
Seems like the voltages are probably normal, but suspect one lead of your voltmeter is on the +5 rail instead of ground, perhaps due to an error in the FAQ instructions...
Double check that the ground lead is at ground potential, eg. the end of C47 nearer the edge of the board. If voltages are still wonky, try putting the ground lead on the chassis (voltages won't be as accurate but not off by 5V).
And check the lead connections at your meter aren't reversed (eg. red to common, black to V) ... this sometimes trips me up.
Good luck!
--- End quote ---
You're right, when measuring off the negative side of C47 I get -12V and +12.9V (the latter seems high!)
What tripped me up, and this may betray how little I know about electronics, is that I thought pin 119 (as well as 115) on the I/O edge connector socket was ground, because when I test continuity between that pin and ground (i.e. the chassis), I get a dead short. But now I do see the 5V on pin 119 under operation. How can this be?
Anyhow, lesson learned that testing continuity with the chassis when the machine is turned off is not a reliable way to identify ground.
sigma7:
--- Quote from: dmark on May 12, 2022, 12:22:56 am ---... when measuring off the negative side of C47 I get -12V and +12.9V (the latter seems high!)
What tripped me up, and this may betray how little I know about electronics, is that I thought pin 119 (as well as 115) on the I/O edge connector socket was ground, because when I test continuity between that pin and ground (i.e. the chassis), I get a dead short. But now I do see the 5V on pin 119 under operation. How can this be?
--- End quote ---
With tremedous thanks due to Al Kossow, the "original" Lisa schematics are available on Bitsavers.org, eg. the Lisa 1 or 2/5 I/O is at http://www.bitsavers.org/pdf/apple/lisa/hardware/050-4008-H_IO.pdf
Page 1 shows the card edge pinout, with pin 119 designated as /PWRSW, which will be tied to ground while the front panel power switch is pressed... possibly explaining your observation.
Pin 115 is +5V, which may show initially a low resistance to ground as there is a lot of capacitance that needs to be charged before reaching a steady state; after a few seconds of measuring resistance to ground, it should be more than a few ohms.
If you measure continuity using the "diode test" feature of a DMM (typically the feature that beeps when there is continuity), note that it can be misleading if one isn't paying sufficient attention to what you are measuring and how that feature works when not used to test diode junctions. Sometimes reversing the leads when using the diode test will quickly reveal that the connection isn't a direct one (since it beeps in one direction but not the other), but this may depend on the meter and circuit. Especially when troubleshooting mysteries, it may be preferable to stick with (or verify with) old fashioned resistance measurements, particularly when the difference between 1 ohm and 100 ohms makes a difference.
Your 12V supply may be a bit high due to minimal load on that rail. Since it is within 10% of 12V, it is probably fine.
+5V should be within +/- 5%, ie. 4.75V to 5.25V, so the power supply should be adjusted to that range.
HTH
Lisa2:
--- Quote from: sigma7 on May 10, 2022, 10:29:09 pm ---An alternative to using an extender is to use the chassis wiring outside of a chassis; I've been using a home-made extender on the power/video connector for quite some time, and use a drive/keyboard cable removed from a chassis for the other connector (instead of a second extender). I think others have all the wiring outside of the chassis, but maybe that is only practical with an external monitor.
--- End quote ---
Using a spare wiring harness, ribbon cable ( including the power switch/ KB jack assembly ), and external monitor is how I run the card cage outside the chassis for debugging.
Rick
blusnowkitty:
--- Quote from: Lisa2 on May 13, 2022, 04:08:33 pm ---Using a spare wiring harness, ribbon cable ( including the power switch/ KB jack assembly ), and external monitor is how I run the card cage outside the chassis for debugging.
Rick
--- End quote ---
What model of monitor is that? Looks like a Conrac 38V44IOCA1?
https://www.ampronix.com/conrac-38v44ioca1-ivtm15a-15v44ioaap
Lisa2:
--- Quote from: blusnowkitty on May 13, 2022, 04:57:46 pm ---What model of monitor is that? Looks like a Conrac 38V44IOCA1?
--- End quote ---
Mine is a Conrac 38-V44IOA-A2. Be careful before you buy one, there were many variations of this model and not all versions will support Lisa's scan rate.
Here are the specs:
Industrial Series #V44 - 15
technical data
High Resolution Monochrome Monitor V44 - 15
(15" = 381mm)
Category Monochrome (CRT)
Format Cabinet (Metal)
Model V44 - 15"
Part Number 38-V44IOA-A2
Screen size 15" (381mm)
Max resolution 1000 TV lines center
800 TV lines corner
Phosphor P4 (white)
Horizontal frequency 15-40kHz
Vertical frequency range 45-90Hz
User controls Front: A/B Switch, Brightness, Contrast, H Position, H Size, Power, V Position, V Size, VTR Switch
Input voltage 100-240VAC 50-60Hz
Power consumption (max) 65W
On screen display No
Video connection BNC loopthrough, channel A/B
Dimensions (WxHxD) Inch: 15.8x11.7x16.6
mm: 400x298x421
Operating temperature 0-40°C
Weight 30.8lb/14.0kg
Warranty One year parts and labor
Approvals UL1950, CSA22.2 950, 89/336/EEC, FCC Class A, FDA CFR21, EN55022 Class A, EN60950
Options Rack Mounting Kit
Accessories AC Power Cord
Operators Manual
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