C64 with power protector (Gotek) and chameleon crashes

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Don't Panic. Please wash hands.
  • When using the chameleon with a C64 with a power protector (gotek) the chameleon does not seem to like it. I get reboots of the chameleon and weird display on the output of the C64 (1084). Tried different C64s and multiple power supplies (Commodore branded). Sometimes it works for a while but then the reboots come in and continue in a reboot loop. I did not find remarks on protectors in relation with chameleon so I wonder what this could be. Without protector it works. The protector itself works fine with a C64 without chameleon. No problem with other cardridges until now.

  • Depending on what kind of circuit it uses there will be a significant voltage drop - which is why adding those "protectors" as seperate devices (instead of building them into the PSU) is generally a bit questionable.

  • THe Chameleon already has a protection circuit: Whenever the voltage on the 5V rail istoo high, a Z-Diode will burn any excess voltage.


    I agree with Tobias - the circuit is "questionable" at best. It may do what it's advertised to do (cut off power upon too-high voltage), but it's not fit for the everyday job of keeping the computer operating properly. If you can, send it back - you don't need it.

  • Okay. Reason I got this protector is because I want to keep using the supplies I have laying around. Maybe I can change the 5v circuit in them then. Generally the protector works for the normal c64 usage except then with the chameleon. Apparently the chameleon draws a bit more current than the average fast loader cardridge.


    I am in touch with the seller of this thing to see if I can send it back (or keep it for the normal use).

  • The voltage drop is 0.05-0.1. I measured the 5V inside the C64 and it is 5.05V. Do you have a suggestion where to measure to find the cause of this? Can it be something else than voltage drop?

  • You always need to measure under load - yes, the Chameleon takes more power than the usual freezer/Fastloader cart, but that should not cause the system to become unstable. Power consumption is about 2.1W (average), so about 420mA, with peaks above that, of course. This is considerably less than for example the original Commodore REU.


    If the seller will disclose the exact circuit, we can estimate what the actual drop under load is. However, the answer should be absolutely clear: Chameleon has overvoltage protection already. You do not need another protector. However, I won't start to advertise this feature, as I cannot guarantee any performance in real-world-random failures. It will limit damage, that's for sure, but it has not been designed to do a specified thing on case X, Y or Z. In other words: There is nothing to advertise.


    First thing I'd ask the seller of such a "protector" is if there is insurance included. If the C64 suffers damage with the thing connected, will the seller or his insurance pay for it? I have my doubts, as the price is rather low, and you can already see that it has not been tested thoroughly. If you get weird behaviour with a Chameleon, you'll have lots of trouble with an REU.


    That means: You do not have proper operation in known-good configurations, and I have my doubts that there is insurance included. So all you've paid for is a little bit of a good feeling, but no actual value. I bet that the "good feeling" is gone already with the improper function. Let me know if you get the good feeling back after knowing the actual coverage in case of a defect.


    To put the cherry on the cake: Please ask the seller if he'll pay for a damage that is caused on Chameleon. If the input voltage is too low, the voltage regulators may go into oscillation, because they are operated outside spec. This won't be covered by warranty, as you should not operate the Chameleon on a known-bad computer. Since the cause of the low voltage is already known here, we will surely send you to the root source of the problem, the vendor of the "protector".

  • I measured the voltage drop on the user port with and without protector. Without (with chameleon inserted) I see it dropping worst case to just 4.5v when switching on and then go back up to 4.98V. With the protector it drops to 4.0V causing the chameleon to crash/reset. The output voltage on the 7805 is a steady 5.05V.


    This protector is a hobby project as far as I can see so no warranty. It is only meant to shut off the power from the old commodore bricks in case the 5V is becoming to high and fry the chips. For me just a security measure without having to buy a more expensive power supply.


    As for the schematic, from the print it looks like the schematic from Ray: https://console5.com/wiki/File:Commodore_64_Computer_Saver_Schematic.png

    Besides the beeper.


    I asked the seller if he can confirm this.


    The seller is willing to return my money so that is not an issue. Now I am trying to understand why the voltage is collapsing with this device which does not look that complex.

  • The last reply was more than 365 days ago, this thread is most likely obsolete. It is recommended to create a new thread instead.