E-mu Emulator Sampler User Forum for the EIII EII EI and EIII XP - Replaced The Screen, Now Only 1MB RAM is Recognized : /

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| | |-+  Replaced The Screen, Now Only 1MB RAM is Recognized : /
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Author Topic: Replaced The Screen, Now Only 1MB RAM is Recognized : /  (Read 736 times)
edude
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« on: July 04, 2017, 02:47:18 PM »

i replaced the screen with an oled, and it works fine

however i made a few booboos (i lightly accidentally scratched a few traces) or maybe shorted something because now it will only recognize 1MB of RAM

also i can't save the os onto floppy, it returns errors when it tries to write

also, some sounds i did manage to load were corrupted and were digital noise. only a few though, otherwise it is ok

also, where before if there was no scsi termination i could not get past the startup screen, now it will flash the error for a split second then go on to load the os

i think i messed this eiiixp up : / none of these errors happened before i replaced the screen

any ideas? this was my backup and i would hate to sell it
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edude
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« Reply #1 on: July 04, 2017, 03:10:18 PM »

i just noticed this though, under where the inverter was

i moved the part a bit when i desoldered it and it seems to have scratched the trace. this trace goes left and to the ram section btw



* trace.JPG (287.39 KB, 885x649 - viewed 32 times.)
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edude
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« Reply #2 on: July 04, 2017, 05:38:22 PM »

a close up


* trace2.JPG (3234.92 KB, 4608x3456 - viewed 39 times.)
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Wolfram
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« Reply #3 on: July 05, 2017, 02:46:56 AM »

Nice cut. ;-)
Remove carefully the lacquer and put a small drop solder on it.
You can measure functionality from the end to end of the trace.
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edude
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« Reply #4 on: July 05, 2017, 03:56:06 AM »

thanks : )

i cleaned the trace and it is not cut. the inverter had caused some residue/corrosion but it is still intact

now it won't even boot up, first it shows the preset definition light for a few seconds then just flashes all lights and no screen
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edude
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« Reply #5 on: July 06, 2017, 05:52:01 AM »

dag namnit, flew too close to the e-mu on wings of noobishness

anybody know what the preset definition diagnostic light means?
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Wolfram
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« Reply #6 on: July 06, 2017, 08:13:47 AM »

Verify the cable connection to the panel board.
Measure the connection from end to end.
Be sure pin 1 is connected to pin 1.
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edude
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« Reply #7 on: July 08, 2017, 07:19:50 AM »

i test using a multimeter yes?
« Last Edit: July 08, 2017, 07:21:32 AM by edude » Logged
Wolfram
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« Reply #8 on: July 08, 2017, 09:05:13 AM »

yes, turn of the EIII set the multimeter to Continuity beeper and check the connection from end to end.
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edude
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« Reply #9 on: July 09, 2017, 10:50:46 AM »

isn't that just checking the cable though? checking pin 1 on panel and pin 1 on main board with cable between only checks the cable for continuity yes?
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edude
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« Reply #10 on: July 11, 2017, 03:33:03 PM »

i checked as many traces as i could on the panel and they are ok, but still not sure what you say
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obsoletemachines
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« Reply #11 on: July 27, 2017, 02:51:25 AM »

hi,
i don't think there is damage to the trace from the photos you sent...the traces run quite deep in this pcb and are not just 'stencilled' on to the PCB.

I think you need to go back to basics and test the power rails first.. what are you getting there.

If the power is ok then something is probably shorting the RAM circuitry - did you drop anything into the board?  Re-seat the ram chips... they may be slightly dislodged. But first as i say check the rails.

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edude
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« Reply #12 on: August 09, 2017, 11:38:37 AM »

hi,
i don't think there is damage to the trace from the photos you sent...the traces run quite deep in this pcb and are not just 'stencilled' on to the PCB.

I think you need to go back to basics and test the power rails first.. what are you getting there.

If the power is ok then something is probably shorting the RAM circuitry - did you drop anything into the board?  Re-seat the ram chips... they may be slightly dislodged. But first as i say check the rails.



thanks  Smiley

i could try soldering the inverter back on and swapping the front panel with one from another eiiix just to test, although since the problems are with ram among other things it may be the main board as you say? the ram chips are soldered on btw i believe

i am not experienced to do anything much besides check the rails, but by rails do you mean the main power rails going to the drives? i'm not sure how to check any other than those
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obsoletemachines
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« Reply #13 on: August 24, 2017, 05:07:11 AM »

hi,

I would advise not to try soldering the inverter back - that has nothing to do with this.

you could try swapping the front panel but it will make no difference, the buffering chips for signalling on the eiiix reside on the main board and not the panel.

i suspect you plugged in the analog board the wrong way - that wide ribbon... can confirm if you did this even once? if so then an octal buffer will have shorted and latched up ...that would prevent ram read and write.

you see, there is a lot of buffering going on in the eiiix - buffering of audio, buffering of signals to the LCD.  there is no 'gate' array or chip it all goes to the National CPU...you latch a buffer up and the bus gets congested.

I don't have a schematic but i've been able to work out how this works as its very elegantly laid out.

I recently bought a faulty Eiiix with a scrambled display and fixed it.


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edude
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« Reply #14 on: September 04, 2017, 04:35:20 AM »

hi,

I would advise not to try soldering the inverter back - that has nothing to do with this.

you could try swapping the front panel but it will make no difference, the buffering chips for signalling on the eiiix reside on the main board and not the panel.

i suspect you plugged in the analog board the wrong way - that wide ribbon... can confirm if you did this even once? if so then an octal buffer will have shorted and latched up ...that would prevent ram read and write.

you see, there is a lot of buffering going on in the eiiix - buffering of audio, buffering of signals to the LCD.  there is no 'gate' array or chip it all goes to the National CPU...you latch a buffer up and the bus gets congested.

I don't have a schematic but i've been able to work out how this works as its very elegantly laid out.

I recently bought a faulty Eiiix with a scrambled display and fixed it.





thanks : )

i might have plugged the analog board cable in the wrong way before either on this machine or the other i'm not sure when though

i think i will have to sell it, i should not have attempted to fix something like this with no experience. will include two hard drives that i found in both machines with sounds on them and an extra oled screen that is still sealed from mouser. the power supply will need some tlc also btw but otherwise the inside is mint

i am also on gearslutz (username: viewing) where i've been a member since 2008
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E-mu Emulator Sampler User Forum for the EIII EII EI and EIII XP - Replaced The Screen, Now Only 1MB RAM is Recognized : /

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