Hi all,
I bought a rather abused but working SPX90 on ebay. I figured having a poke about inside and perhaps re-capping it / replacing the screen etc might be an interesting project for an amateur such as myself. It has raised a lot of questions though. If anyone is able to educate me on any of my queries i'd sure appreciate it. I am recording the journey for youtube so i'll leave a link at the end of this post for anyone who has the interest.
On replacing the screen:
I have established that the screen is a generic 1602 hd44780 based display with 5v backlight which is a generic part, although exact dimensions of the pcb are uncommon. From what i can tell the connenction is a standard 14 pin (2x7) Female to male IDC cable. With a seperate 2 pin power supply.
I ordered an aliexpress replacement display which was hard to find in the 2x7pin format. Being aliexpress it didnt come with a datasheet, and to be fair I dont know which pin is which on the SPX anyway, but i found i couldnt get output from the original cable with the new display, and I also ended up damaging the original cable.
So here's the weird bit... I soldered turrets to the original display and bouight a Female to famale IDC cable, Uppon connecting the cable to the display i get no output still and the chip gets really hot suggesting it is wired wrong. I tried every orientation including flipping the IDC connector to the other side of the ribbon but could not get output. However if i connect the turrets individually to the main board using single jumper cables the display works.
SO I think i need education on:
On The power Supply:
This one has seen some abbuse, The board is severely discoloured, the power switch is missing and bridged for always on operation, and it looks like its been partially recapped. Ok.. so its working and putting out the right voltage.. Whats worrying me though is if i touch the chasis, or wiggle the ground wire, when it is connected to nothing other than the power, i get an audiable pop from my studio monitor speakers which are not conencted to the unit but share a multiplug. My immediate thought is i need to re-cut and crimp the ground wire, but other than this im lost. Could there be current leaking to ground? How can I test for this without just shotgun replacing every cap?
Just out of curiousity, is it possible to purchase a more modern cooler running generic PSU that could be spliced in to this unit in a squeese?
Cheers.
Dave
😀
YouTube
I bought a rather abused but working SPX90 on ebay. I figured having a poke about inside and perhaps re-capping it / replacing the screen etc might be an interesting project for an amateur such as myself. It has raised a lot of questions though. If anyone is able to educate me on any of my queries i'd sure appreciate it. I am recording the journey for youtube so i'll leave a link at the end of this post for anyone who has the interest.
On replacing the screen:
I have established that the screen is a generic 1602 hd44780 based display with 5v backlight which is a generic part, although exact dimensions of the pcb are uncommon. From what i can tell the connenction is a standard 14 pin (2x7) Female to male IDC cable. With a seperate 2 pin power supply.
I ordered an aliexpress replacement display which was hard to find in the 2x7pin format. Being aliexpress it didnt come with a datasheet, and to be fair I dont know which pin is which on the SPX anyway, but i found i couldnt get output from the original cable with the new display, and I also ended up damaging the original cable.
So here's the weird bit... I soldered turrets to the original display and bouight a Female to famale IDC cable, Uppon connecting the cable to the display i get no output still and the chip gets really hot suggesting it is wired wrong. I tried every orientation including flipping the IDC connector to the other side of the ribbon but could not get output. However if i connect the turrets individually to the main board using single jumper cables the display works.
SO I think i need education on:
- Do common cheapie 1602 displays need further tweaking/components to work in an SPX 90?
- And am I getting something wrong with the IDC cable idea?
On The power Supply:
This one has seen some abbuse, The board is severely discoloured, the power switch is missing and bridged for always on operation, and it looks like its been partially recapped. Ok.. so its working and putting out the right voltage.. Whats worrying me though is if i touch the chasis, or wiggle the ground wire, when it is connected to nothing other than the power, i get an audiable pop from my studio monitor speakers which are not conencted to the unit but share a multiplug. My immediate thought is i need to re-cut and crimp the ground wire, but other than this im lost. Could there be current leaking to ground? How can I test for this without just shotgun replacing every cap?
Just out of curiousity, is it possible to purchase a more modern cooler running generic PSU that could be spliced in to this unit in a squeese?
Cheers.
Dave
😀
YouTube
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there's really nothing simple or generic about an SPX90 (and it's been a while since i fixed one) and as i recall about 99% of problems are due to supply issues (they live with inadequate venting and heatsinking due to the one rack space they live in)
as for the display if the old one worked why change it? (if it's because of visual impairment due to surface scratches of the front bezel those can be buffed)
as for the display if the old one worked why change it? (if it's because of visual impairment due to surface scratches of the front bezel those can be buffed)
- The Backlight was all but completely dead making the screen hard to read.
- The unit is pretty beaten up and modified and has no collectable value
- I couldnt see any backlights for sale by themselves an an entire new display was only £1.50, so I had the whole display anyway
- And i'm really interested in learning about this stuff, I'd like to learn so that if i buy future doer uppers I know whats required to fix the display.
- People are charging like £50 for replacement displays. I'd like to spread the word on how to make your own if you have the time/means.
I've got the Screen working.. but i'd still liek to try fabricating a new one.
well not my area of specialty but there all manner of criteria that affect the selection of displays such as whether or not they are alpha/ numeric (some low cost displays are text only) clock rates are critical as well as line addressing for matrixing but that's a whole area of speciality far beyond the level of fixer upper catergory (and me)
the backlight issue is easily resolved with a few well placed led's.
i'll hope you come to a good ends to your efforts...no offense intended.
to wit i was quite fond of the SPX90 in my days as a touring soundman!
the backlight issue is easily resolved with a few well placed led's.
i'll hope you come to a good ends to your efforts...no offense intended.
to wit i was quite fond of the SPX90 in my days as a touring soundman!
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