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LED part for Woodstock machines
11-23-2015, 06:43 PM
Post: #1
LED part for Woodstock machines
FYI

I ran across this listing on eBay for what appear to be replacement LEDs for Woodstock machines. $16 including shipping from Ukraine. Seems reasonable, if someone can confirm this is indeed the proper part.

I'm not affiliated with seller, just passing on info for folks that do these repairs.

--Bob Prosperi
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11-24-2015, 12:28 AM
Post: #2
RE: LED part for Woodstock machines
(11-23-2015 06:43 PM)rprosperi Wrote:  FYI

I ran across this listing on eBay for what appear to be replacement LEDs for Woodstock machines. $16 including shipping from Ukraine. Seems reasonable, if someone can confirm this is indeed the proper part.

I'm not affiliated with seller, just passing on info for folks that do these repairs.

I'm afraid that those modules have only 9 digits, and Woodstocks have 12. Anyway, there is already a trusty supplier for replacement displays (as long as LED chips are available), our fellow forum member Panamatik:

http://www.panamatik.de/html/hp_calculat...r_kit.html

Kind regards,
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11-24-2015, 03:54 PM
Post: #3
RE: LED part for Woodstock machines
(11-24-2015 12:28 AM)ElectroDuende Wrote:  I'm afraid that those modules have only 9 digits, and Woodstocks have 12.

oops. Careless mistake, not even noticing the digit count, sorry for that. What kind of calculator are these likely for, or perhaps seller simply exaggerated their use to sell more?

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11-24-2015, 04:07 PM
Post: #4
RE: LED part for Woodstock machines
A lot of 8-digit LED calculators from the 70's (either 4-operation or basic scientific) used this kind of 9-digit displays. It was also used on some microprocessor kits such as the MK14 from Science of Cambridge.
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11-26-2015, 11:07 AM (This post was last modified: 11-26-2015 11:11 AM by PANAMATIK.)
Post: #5
RE: LED part for Woodstock machines
(11-24-2015 12:28 AM)ElectroDuende Wrote:  I'm afraid that those modules have only 9 digits, and Woodstocks have 12. Anyway, there is already a trusty supplier for replacement displays (as long as LED chips are available), our fellow forum member Panamatik:

http://www.panamatik.de/html/hp_calculat...r_kit.html

Kind regards,

Thanks for the "trusty supplier". Smile Indeed my woodstock replacement LED modules are still available and ready for "plug and play".

The digits have a slightly different appearance than the originals, because they are about 15% smaller in size (45 mm instead of 54mm). And due to the higher components they are finally located nearer to the red display cover. But they are a real replacement, and the only one that I know of, in case that you have to fix a defective woodstock display.

Unfortunately I cannot sell them for 16$, because my cost were about 22$ each, 12 alone for buying the LED modules. But shipping without insurance could be reduced to 2$.

I tried to build also a replacement for spice series calculators, but didn't make it yet, you need to build your own adapter. For pinout description see attachement.

.pdf  LEDDisplay.pdf (Size: 106.09 KB / Downloads: 20)

Bernhard

That's one small step for a man - one giant leap for mankind.
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11-26-2015, 11:38 AM (This post was last modified: 11-26-2015 12:34 PM by ElectroDuende.)
Post: #6
RE: LED part for Woodstock machines
(11-26-2015 11:07 AM)PANAMATIK Wrote:  Thanks for the "trusty supplier". Smile Indeed my woodstock replacement LED modules are still available and ready for "plug and play".

The digits have a slightly different appearance than the originals, because they are about 15% smaller in size (45 mm instead of 54mm). And due to the higher components they are finally located nearer to the red display cover. But they are a real replacement, and the only one that I know of, in case that you have to fix a defective woodstock display.

Unfortunately I cannot sell them for 16$, because my cost were about 22$ each, 12 alone for buying the LED modules. But shipping without insurance could be reduced to 2$.

I tried to build also a replacement for spice series calculators, but didn't make it yet, you need to build your own adapter. For pinout description see attachement.

Bernhard

I took a bried look to this after our conversation (consdering that it took me several months to restore a couple of calculators, and that my arduinos are in "deep storage" since a long time ago, it was all I could do) Where do you guys buy free time for all this things???

The two problems I see here are:

- The one you noted about spice using independent lines both for annode and cathode of sign indicator, and led moludles having them "shared".
- The fact that spice has both decimal radix and comma. I suppose the way to solve this is connecting the "dot" of led modules to the "comma" and setting the machine to use comma as a decimal radix (done cutting a jumper in the power board) As the comma only ligths when separating decimals, and the dot ligths both on decimals and thousands.

I'll patiently wait for skilled guys like you to solve the problem, and then buy a replacement from you. ;-)

By the way, I removed the clear plastic magnifier over my spice LED module... WOW! Looking at those tiny led modules connected by almost imposible to see gold wires is amazing!
There is some green corrosion on the tracks but I face a dilemma... if I try to clean it, I can break the wires (only half digit is currently failing). If I don't clean, it may end ruining more segments...
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11-26-2015, 11:54 PM
Post: #7
RE: LED part for Woodstock machines
(11-26-2015 11:38 AM)ElectroDuende Wrote:  I took a bried look to this after our conversation (consdering that it took me several months to restore a couple of calculators, and that my arduinos are in "deep storage" since a long time ago, it was all I could do) Where do you guys buy free time for all this things???

The two problems I see here are:

- The one you noted about spice using independent lines both for annode and cathode of sign indicator, and led moludles having them "shared".
- The fact that spice has both decimal radix and comma. I suppose the way to solve this is connecting the "dot" of led modules to the "comma" and setting the machine to use comma as a decimal radix (done cutting a jumper in the power board) As the comma only ligths when separating decimals, and the dot ligths both on decimals and thousands.

I'll patiently wait for skilled guys like you to solve the problem, and then buy a replacement from you. ;-)

By the way, I removed the clear plastic magnifier over my spice LED module... WOW! Looking at those tiny led modules connected by almost imposible to see gold wires is amazing!
There is some green corrosion on the tracks but I face a dilemma... if I try to clean it, I can break the wires (only half digit is currently failing). If I don't clean, it may end ruining more segments...

I think it is possible to make a replacement for spice LED display when you add some logic gates to the board. The decimal segment can be driven only if decimal and not comma is output. The minus sign must be multiplexed together with other segments. I think there can be used a CPLD or GAL that can do this job. But the smaller size of the QDSP modules gives a worse proportion for spice models, because spice digits are even bigger than woodstocks.

The question will be, is there a demand for a spice replacement LED display? If there is i will make the display when i have time.

I dont think that the green corrosion will get worse when the calculator is stored in normal dry condition.

Bernhard

That's one small step for a man - one giant leap for mankind.
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