Please help . OSSC No test pattern, no LCD text, both LEDs lit

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    Had my 1.5 OSSC with audio board for a few years now. Never given me any problems. Went to turn it on this morning as usual, and all I get is the following symptoms

    No test pattern
    No audio
    LCD is lit but no text
    Red and Green LEDS permanently lit

    I’ve tested the following

    Voltage regulators have no shorts between ground and VCC
    Same behaviours whether SCART from a console is in or out
    Removed audio board, same issues
    Fuses F1 F2 (these are fuses right?) are fine

    I’ve brought up schematics for the DIY build to see if I get voltages on some easy to access pins on U1, U2 and U3, they do show voltages around the 3.3v mark (although one of the chips, I forget which one, was showing 1.1v, I think it was U3). Although I’m not sure what they should show to be honest. Also tested the oscillator with my simple, not very good handheld scope, and I get an output of 1.8kc which I think equates to 1.8khz (I’m not very good with scopes though so I may be using it wrong) but there is a definite output from the output pin of the oscillator. Also the oscillator has continuity with the CLK27 pin of the Altera fpga.

    I don’t have a USB blaster to test the FPGA using the JTAG port. That was going to be my next thing to try, but it means I have to buy one.

    Any thoughts anyone? I love my OSSC and I want to carry on using it 🙁



    U6 3.3
    U7 1.9
    U9 1.9
    U12 1.2
    U13 2.5
    U14 1.2
    U15 1.8
    U16 1.8

    U5 3.3


    Definitely worth trying to JTAG the unit, if the FPGA doesn’t respond at all it may need to be replaced.


    Thanks, I pretty much expected to get a usb blaster. I’m hoping this one will work Amazon means I get it today and it’s cheap so fingers crossed I get some kind of results later today.


    Right, well that was strange.

    Installed v17.1 of the Quartus programmer software. Could’nt work out what I was supposed to do, so I just followed the JTAG firmware update instructions to the letter. Flashed version 0.87-aud as there was no JTAG 0.88-aud available. It seemed to be going ok, then I got the messages below

    Info (209060): Started Programmer operation at Sat Apr 17 22:43:45 2021
    Info (209016): Configuring device index 1
    Info (209017): Device 1 contains JTAG ID code 0x020F20DD
    Info (209007): Configuration succeeded — 1 device(s) configured
    Info (209018): Device 1 silicon ID is 0x14
    Info (209044): Erasing ASP configuration device(s)
    Info (209023): Programming device(s)
    Info (209021): Performing CRC verification on device(s)
    Error (209040): Can’t access JTAG chain
    Error (209027): Verification failed for device number 1
    Error (209012): Operation failed
    Info (209061): Ended Programmer operation at Sat Apr 17 22:44:48 2021

    I unplugged the OSSC and switched if off and on again, and its working! Well I have stuff on the LCD screen and I can operate it with the remote etc. Bit late to plug it into anything at the moment but I will try tomorrow. Since its working I decided to update to 0.88-aud the SD card method. And that worked as well. So…. yeah I don’t know how I got it to work tbh…

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