Scanner Disk: Enter LED Will Not Light...LED, button, or?

[who]

When I run the scanner disk all of the front panel LEDs illuminate except the enter LED.  I disassembled the button and cleaned the contacts, but no luck.  Do you think the button is broken or the LED?  Maybe something else?

If it is the LED, how do I go about finding a replacement?  Any tips for finding replacement parts?

[alka]

Judging from your last issue with the new display you may be experiencing scanner issues... try carefully swapping the main z80 CPU chip with the scanner z80 CPU chip and see if any of the behavior changes..

[who]

Hi Alka,

Thanks for all your help!  I have two front panels, one works fine, the other has issues.  I was told the new front panel works except for one slider.  I broke one of the major troubleshooting rules and changed more than one thing at a time before I installed it.  I changed out all four sliders, put in a new OLED and replaced the large ribbon cable.  (I've done a fair amount of work to my EII and got a little too confident.)  Long story short, I think all of my issues are either due to problems with the front panel, or due to problems I introduced by changing parts on the front panel.

I swapped the old ribbon cable back in (easy) and the problems still occurred.  My next step is to pull the boards off the front panel and look for issues.  I don't know how often LEDs go bad, but my guess is it is much more likely there is a problem with the button.

[who]

I've determined it is not the switch and I put in a new LED and it still doesn't light.  Is there another component that may be failing?

[who]

I confirmed the old LED works and put it back in place of the new one, so it must be something else.

[who]

I have an an extra front panel that is known to work.  I tried replacing the pcb under the right side (where the enter LED is) and still have the same problem.  It must be a component on the left pcb.

[who]

The problem was a faulty 74LS273 PC.  Fairchild flip flop logic chip (?)

[alka]

glad you got that sorted! are you all working now?

[who]

Hi Alka,

Thanks for your help and interest!  I replaced the display with a kit purchased on Ebay.  I'm not 100% satisfied as the viewing angle is narrow.  I may try this kit next:

https://www.ebay.com/itm/SP12-SP1200-OG-LED-display-Wide-viewing-angle-Best-quality-FSTN-technology/263088879227?hash=item3d4151b67b:g:dNMAAOSwLEtYk796

I bought one for my SP-1200 and it's pretty nice.  However, I would really like an OLED like I have in my Emax and EIII.  (I can read those from across the room!)  I just haven't been able to find one that works with the EII.

As for the rest of the EII, I want to replace the keybed next.  I'm done after that!

[alka]

This is the one i used but i had to lug it to get it to work with the EII timing... http://www.newark.com/midas/mc21605a6wd-bnmlw-v2/display-alphanumeric-16x2-white/dp/03AC3420?ost=Midas+MC21605A6WD-BNMLW&iscrfnonsku=false&ddkey=http%3Aen-US%2FElement14_US%2Fsearch

I have heard of other folks using it fine no problem though....

for example:

http://www.nattvard.com/cmi/e-mu-emulator-ii-lcd-screen-change/

[who]

Hi Alka,

Thanks for the suggestion!  When you say "lug" it, what do you mean?

[alka]

good question.. i think i made that term up... the capacitor fix on the timing pin as noted elsewhere did not work for me, however when i was testing a noticed that when i had a sole oscilloscope probe attached to the timing pin of the display it loaded fine... not being an expert in electronics and having spent a year getting the EII sorted i was happy to just keep the probe attached and packed it up neatly in the case...  strange i know.. but it works consistently.. no issues and a nice bright display.