Author Topic: Replacing LED display when original replacement part no longer avail.  (Read 1872 times)

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Offline gooseEL34

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Ok.  Here is the image of what I am working with.  Unit is a guitar processor from the late 80s.

sgx_mid by hondaca77, on Flickr

Unit has a rotary data knob and there is a 3 digit LED that shows the patch number 1-128 in the window.  The repair part is no longer available from ART.  Is this something that I could attempt to fix with a generic part?  I know nothing of how these counters work, but I am handy with a soldering iron, Fluke meter and a Scope if need be.

I notice I can get a three digit 7 segment LED display on ebay cheap.  What parameters should I watch out for?


Thanks
Tim
« Last Edit: January 29, 2015, 05:23:49 pm by gooseEL34 »
 

Offline wraper

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Re: Replacing LED display when original replacement part no longer avail.
« Reply #1 on: January 29, 2015, 05:25:11 pm »
You can stick any led displays (seems to be 3 of them) with the same pinout and right configuration (common cathode or anode), likely will be brighter than old ones. Why do you think it is faulty? I would expect driving circuit to be dead unless it is just one failed segment.
« Last Edit: January 29, 2015, 05:26:45 pm by wraper »
 

Offline gooseEL34

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Re: Replacing LED display when original replacement part no longer avail.
« Reply #2 on: January 29, 2015, 05:32:09 pm »
When it should read 001 I only get the bottom segement of the digits plus the lower left leg segement of the 1st digit
 

Offline SeanB

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Re: Replacing LED display when original replacement part no longer avail.
« Reply #3 on: January 29, 2015, 06:26:40 pm »
That looks more like dead driver transistors, or an open circuit in a connection to the display, likely broken PCB tracks, dry joints or a cracked DIL resistor array for the one set of drives. Might just be very dirty display sockets as well.
 

Offline jlmoon

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Re: Replacing LED display when original replacement part no longer avail.
« Reply #4 on: January 29, 2015, 06:39:11 pm »
Ok.  Here is the image of what I am working with.  Unit is a guitar processor from the late 80s.

sgx_mid by hondaca77, on Flickr

Unit has a rotary data knob and there is a 3 digit LED that shows the patch number 1-128 in the window.  The repair part is no longer available from ART.  Is this something that I could attempt to fix with a generic part?  I know nothing of how these counters work, but I am handy with a soldering iron, Fluke meter and a Scope if need be.

I notice I can get a three digit 7 segment LED display on ebay cheap.  What parameters should I watch out for?


Thanks
Tim

Those look very much like "Monsanto MAN-7" (were made both in common anode and common cathode flavors) led displays.  They are kind of rare but still can be obtained if needed.  What are the heights of the segments?   If you look on the side of their bodies you might find a manufacturers part number, should help you tremendously. 

Hope this helps,

JM


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Offline wraper

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Re: Replacing LED display when original replacement part no longer avail.
« Reply #5 on: January 29, 2015, 08:06:56 pm »
When it should read 001 I only get the bottom segement of the digits plus the lower left leg segement of the 1st digit
Some dead electronics, VERY unlikely to be faulty display.
 

Offline lowimpedance

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Re: Replacing LED display when original replacement part no longer avail.
« Reply #6 on: January 30, 2015, 02:26:09 am »
As others have said its much more likely to be whats driving the display than the display itself.
Some photo's of the inside where the display pcb and connections etc are could be useful.
The odd multimeter or 2 or 3 or 4...or........can't remember !.
 


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