14 Jan
2015
14 Jan
'15
4:28 p.m.
Jay, leds hasn't changed much from years ago. Electronicaly, i believe any
led of same size/format/color will fit. Of course i can dig deeper if you
want
enviado do meu telemovel
Em 14/01/2015 19:25, "Jay West" <jwest at classiccmp.org> escreveu:
Yep, I'm still working on "restoration" of the Microdata Reality.
I say "restoration", because due to another restoration project that
actually has a deadline, I only have time to clean up the microdata and
repair just obvious visual brokenness, not actually start testing/repairing
it electronically. That will come after the "deadline project" J
As most know, schematics and detailed documentation are nonexistent for this
machine.
I've done the rack, the disc drive, the tape drive, and the power supply. On
to the last item, the front panel.
Virtually all of the LED's on the front panel board had so much mouse pee
that the leads on the LEDS actually corroded through, so I need to replace
them all.
Without schematics, can anyone suggest how I might go about determining a
suitable replacement LED from an electrical perspective?
Pictures at www.ezwind.net/microdata/restoration
Best,
J
14 Jan
14 Jan
9:44 p.m.
Howdy gents,
On Wed, Jan 14, 2015 at 3:28 PM, Alexandre Souza <
alexandre.tabajara at gmail.com> wrote:
Jay, leds hasn't changed much from years ago.
Electronicaly, i believe any
led of same size/format/color will fit.
As one who has recently rebuilt an early 70s Altair 8800, I can inform you
that a great deal has changed, in the LED world.
The very inexpensive 'standard' red LEDs which I obtained to replace the
failed units in the Altair were magnitudes brighter than the original
parts, when fed from the same power sources. I ended up having to increase
the value of the series resistors by hundreds or even thousands of ohms,
just to maintain a similar level of brightness vs. the old LEDs.
I'd have to take a look inside, but I believe the values jumped from 300R
to several K in most cases. The new tech is so much more efficient than the
stuff kicked-out in the 70s!
9:53 p.m.
drlegendre, he will change ALL of the leds, by what he said. So he doesn't
need to worry about how bright they will be. Also, there are hi-bright leds
and lo-bright leds, I believe he will use the least expensive, less bright
ones by default.
On Thu, Jan 15, 2015 at 12:44 AM, drlegendre . <drlegendre at gmail.com> wrote:
Howdy gents,
On Wed, Jan 14, 2015 at 3:28 PM, Alexandre Souza <
alexandre.tabajara at gmail.com> wrote:
Jay, leds hasn't changed much from years ago.
Electronicaly, i believe
any
led of same size/format/color will fit.
As one who has recently rebuilt an early 70s Altair 8800, I can inform you
that a great deal has changed, in the LED world.
The very inexpensive 'standard' red LEDs which I obtained to replace the
failed units in the Altair were magnitudes brighter than the original
parts, when fed from the same power sources. I ended up having to increase
the value of the series resistors by hundreds or even thousands of ohms,
just to maintain a similar level of brightness vs. the old LEDs.
I'd have to take a look inside, but I believe the values jumped from 300R
to several K in most cases. The new tech is so much more efficient than the
stuff kicked-out in the 70s!
15 Jan
15 Jan
12:02 a.m.
On 2015-Jan-14, at 6:53 PM, Alexandre Souza wrote:
On Thu, Jan 15, 2015 at 12:44 AM, drlegendre .
<drlegendre at gmail.com> wrote:
Nonetheless, even 'normal' modern LEDs can be much more efficient than LEDs of the
early-mid-70s, and even if replacing all of them for uniformity they might look out of
character or non-original if not adjusted for brightness.
The target current for an LED in the 70s would typically be 20mA as I recall, while 10mA
or less will generally do today.
A few months ago when that television series about the PC-era compatibles-vs-IBM story was
being mentioned on the list, I went off to watch the preview on youtube. There was a scene
where the engineer was hacking over the IBM-PC to get ROM-dumps or some such and had a
bunch of breadboards filled with blinken LEDs. Being in critic/pedant mode, as soon as I
saw the lit LEDs I immediately thought "LEDs didn't look like that in
1983".
Howdy gents,
On Wed, Jan 14, 2015 at 3:28 PM, Alexandre Souza <
alexandre.tabajara at gmail.com> wrote:
drlegendre, he will change ALL of the leds, by what he said. So he doesn't
need to worry about how bright they will be. Also, there are hi-bright leds
and lo-bright leds, I believe he will use the least expensive, less bright
ones by default. Jay, leds hasn't changed much from years ago.
Electronicaly, i believe
any
led of same size/format/color will fit.
As one who has recently rebuilt an early 70s Altair 8800, I can inform you
that a great deal has changed, in the LED world.
The very inexpensive 'standard' red LEDs which I obtained to replace the
failed units in the Altair were magnitudes brighter than the original
parts, when fed from the same power sources. I ended up having to increase
the value of the series resistors by hundreds or even thousands of ohms,
just to maintain a similar level of brightness vs. the old LEDs.
I'd have to take a look inside, but I believe the values jumped from 300R
to several K in most cases. The new tech is so much more efficient than the
stuff kicked-out in the 70s!
2:17 a.m.
----- Original Message -----
From: "Brent Hilpert" <hilpert at cs.ubc.ca>
Sent: Thursday, January 15, 2015 12:02 AM
... even 'normal' modern LEDs can be much more
efficient than LEDs of the
early-mid-70s, and even if replacing all of them for uniformity they might
look out of character or non-original if not adjusted for brightness.
----- Reply -----
Just in case someone /does/ want to match up some existing ones I have a few
bags of LEDs from 30 or 40 years ago, both new and pulls; ya never know...
m
14 Jan
14 Jan
10:02 p.m.
Drlegendre wrote...
The very inexpensive 'standard' red LEDs which I obtained to replace the failed
units in the Altair were magnitudes brighter than the original parts, when fed from the
same power sources. I ended up having to increase the value of the series resistors by
hundreds or even thousands of ohms, just to maintain a similar level of brightness vs. the
old LEDs.
I'd have to take a look inside, but I believe the values jumped from 300R to several K
in most cases. The new tech is so much more efficient than the stuff kicked-out in the
70s!
------
In my case, I'm not replacing just a few LEDs, I'm replacing every one of them. As
a result I have a much wider tolerance aesthetically as to the brightness. That being
said, I don't want to blast the room and hurt my eyes looking at them ;)
The ones I'm going to be looking for have axial leads at least 1.5" long, and the
bulb diameter is 4.6 or 4.7mm (with the slightly wider collar at the bottom). I'm
hunting....
Thanks!
J
11:08 p.m.
Ah, OK - my mistake!
Sorry, gents.. I wasn't following closely enough, and had the impression
that he was trying to mix old & new LEDs..
Thank you for replying and correcting my misunderstanding(s).
On Wed, Jan 14, 2015 at 9:02 PM, Jay West <jwest at classiccmp.org> wrote:
Drlegendre wrote...
The very inexpensive 'standard' red LEDs which I obtained to replace the
failed units in the Altair were magnitudes brighter than the original
parts, when fed from the same power sources. I ended up having to increase
the value of the series resistors by hundreds or even thousands of ohms,
just to maintain a similar level of brightness vs. the old LEDs.
I'd have to take a look inside, but I believe the values jumped from 300R
to several K in most cases. The new tech is so much more efficient than the
stuff kicked-out in the 70s!
------
In my case, I'm not replacing just a few LEDs, I'm replacing every one of
them. As a result I have a much wider tolerance aesthetically as to the
brightness. That being said, I don't want to blast the room and hurt my
eyes looking at them ;)
The ones I'm going to be looking for have axial leads at least 1.5" long,
and the bulb diameter is 4.6 or 4.7mm (with the slightly wider collar at
the bottom). I'm hunting....
Thanks!
J
3512
days inactive
3513
days old
6 comments
5 participants
participants (5)
-
alexandre.tabajara＠gmail.com -
drlegendre＠gmail.com -
hilpert＠cs.ubc.ca -
jwest＠classiccmp.org -
mhs.stein＠gmail.com