Is some protection possible for the SID chip?


  • mUItAnt
  • 450 Views 16 replies

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  • Is some protection possible for the SID chip?

    hi all,
    after reading about the problem of, sometimes the SID chip can be permanently damaged if you connect/disconnect a C64 audio cable from external amplifier/speakers while the C64 is powered on, is there any protection which could be used (such as a small circuit board) in-between the C64 and the audio amplifier/speakers, so that the SID chip becomes less sensitive and vulnerable to damage?
  • A user of this forum published a project for this some time ago: forum64.de/index.php?thread/61…&postID=953920#post953920 - it needs to be powered from one (internal) or two 9V (external) batteries to keep the output fully isolated from the C64.

    Or maybe you could buy a cheap ADC box that provides optical SPDIF on its output and mount it inside the C64?

    Source Code

    1. 10 x=rnd(-1963):fori=1to81:y=rnd(1):next
    2. 20 forj=1to5:printchr$(rnd(1)*16+70);:next
    3. 30 printint(rnd(1)*328)-217
    sd2iec - tapecart - GCVideo
  • hey thanks Unseen i just read through the thread you linked
    (well i could only read it using auto-translate to english)
    i did not really understand everything very well
    does anyone know if there is something ready-made i can buy, eg. perhaps up to 30 euros price?
    Unseen the cheap ADC box sounds interesting, if it is not too much trouble do you have a link or some further information about that?
  • mUItAnt wrote:

    Unseen the cheap ADC box sounds interesting, if it is not too much trouble do you have a link or some further information about that?
    Something like this (assuming it is really an ADC and not a DAC, the description seems to be mixed up). Since the optical output is completely isolated, you can hot-plug that all day long without any risks for your SID, as long as you don't disconnect the connection from the SID to the box.

    Source Code

    1. 10 x=rnd(-1963):fori=1to81:y=rnd(1):next
    2. 20 forj=1to5:printchr$(rnd(1)*16+70);:next
    3. 30 printint(rnd(1)*328)-217
    sd2iec - tapecart - GCVideo
  • hey thanks very much guys i really appreciate the help

    Unseen, i think you are correct that it looks like your ebay link could be a DAC

    however i found this alternative instead:
    amazon.co.uk/Easyday-Converter…gital-Black/dp/B07F1HB44T

    do you think that would be ok?

    i'm just a little confused about: can i use both (either) the Optical Digital PCM output, or the SPDIF Coaxial Audio output, and regardless of which output is used, it would mean the SID has protection? and for both (either) the Optical Digital PCM output, and the SPDIF Coaxial Audio output, would i be able to input that signal into any regular standard (eg. vintage?) amplifier/speakers, for example like the amplifier/speakers i used previously with the analog C64 audio output? (or do i need some kind of new modern/special 'digital' amplifier system?)

    thanks!
  • As it's not clear how exactly the little box is operating,
    you're only 100% safe using the optical output.
    It's the only way to ensure you can touch the output
    cable without risk for electro-static discharge, as it is
    not an actual cable but an optical fiber.
    This means that your amplifier will need to have a digital
    optical input. It would need to have a digital input
    even in case you'd only need the electric SPDIF.
    Though, the reverse kind of box might exist which converts
    the optical Toslink back to a standard line signal with
    RCA outputs. That could be plugged into your vintage
    amp.

    The post was edited 1 time, last by i u s ().

  • Then get another little external box that converts the optical signal back to an analogue which you can feed into any old amp. The optical transmission is only needed for making electrical isolation 100% sure.
    @Unseen linked to a nice schematic that will do the same which you could integrate into the C64. But you'd have to build the circuitry yourself.
  • i u s wrote:

    As it's not clear how exactly the little box is operating,
    you're only 100% safe using the optical output.
    It's the only way to ensure you can touch the output
    cable without risk for electro-static discharge, as it is
    not an actual cable but an optical fiber.
    Still got my C64 from 1983 - so nearly 40 years of connecting/disconnecting my breading using dozens of different amps. Never got problems - so is this protection stuff really necessary?
  • It seems very theoretical to me, too, but if this would make his sleep better, why not try to help him. ^^ The only chip I remember that I actually destroyed was an AMD Athlon from the generation that had no heat spreader, and I broke it mechanically when I installed the heatsink. This chip has been my keychain pendant for the last 15 years....
  • interesting, convert it back to analog again :D

    (well now i wonder, would the special SID sound change after all of this audio processing... heheh)

    sorry if i am becoming annoying but, one more question i hope, about what is the actual cause of the risk to the SID chip,
    it's 'electro-static discharge' which might damage the SID chip then?, and this could be caused by plugging/unplugging audio cables while equipment is on? it's that simple? (so, if you dont plug in/unplug the cables when the devices are on, there is no need for worry really?)

    thanks, yes i probably do worry too much :)
  • Any conversion from analogue to digital and back can induce unwanted changes to the signal. But I doubt that you will hear them, unless you can also hear the grass grow. ;)

    There is a multitude of possible causes of damage that could happen to the SID. A malfunction or wrong pinout of the video plug, especially in combination with malfunctions of the connected equipment might lead to whatever effects. ESD is mostly caused by electro-static charge of someone who touches any lead that is directly connected to the SID. So, the paddle inputs could be damaged while the chip is still playing fine. Another possible enemy might be a failure of the power supply, applying over voltage from inside. And, of course, heat might also speed up the chip's decay, but there is no proof for or against that. It's just that we know that with higher power dissipation per chip area, heat becomes an obvious chip killer, while we don't know for sure about the SID. So, we're certainly not doing anything wrong if we cool it. Well, like with your birthday cake, it's in best shape if it's not being consumed. ;)
  • hey thanks again i u s, after thinking about the options i think i will just carry on as normal for now and be really careful not to plug/unplug anything while the C64 is switched on (and always make sure the C64 is the last thing to be powered on when switching everything on at the start of a session..)

    now i know there are some protection options available though so that's good to know :)
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