More on the Cheetah Rampack

I should be more careful about doing "repeats" ( I should learn some manners) but I could not find anything recent on these .

But here is on WOS thread on it from the past:-

https://sinclairzxworld.com/viewtopic.php?t=540

Comments


  • So it appears that a slightly more powerful power supply is useful for these .My one came with some instructions and a Memory Test Program . So maybe my idea of using a Retroleum Smartcard with it is a bit superfluous.

  • A side issue.

    The remark by Gozzo (on the Sinclair ZXworld thread) about positive polarity intrigued me . Is this correct?
  • edited October 2019
    Abit off topic again but I found this as well:-

    https://comp.sys.sinclair.narkive.com/Epa2DUhW/mixing-and-matching-wires-and-hardware

    So the Zx81 really does have centre positive polarity (unblievable) on the power supply?

    This seems to be a recipe for power supply problems . I still cannot believe it

    Post edited by harriusherbartio on
  • edited October 2019
    Seeing as the plugs for the ZX81 and Spectrum power supplies are totally different and one will not plug into the other this really is a non problem.

    Meanwhile here's Tom with the weather..
    Post edited by moggy on
  • Reply to Moggy

    Thanks for the info . I did not get a ZX81 power supply so I did not know that . My point about some online sellers saying their supplies work on both is amusing (or not)
  • Now I have seen the capacitor leakage in the ZX81 Rampak ,I think I will check the Cheetah Zx Spectrum Rampack for leakage as well .
  • Now I have seen the capacitor leakage in the ZX81 Rampak ,I think I will check the Cheetah Zx Spectrum Rampack for leakage as well .

    Please do not use the ZX81 RAM pack if it has leaking capacitors as you can easily damage the ULA chip or cause some other damage.

    Hopefully 1024MAK will see this and offer advice on how to repair it.
    I find his advice well worth listening to and in my opinion he's the most knowledgeable guy for all things 81 and explains things in an easy to understand way.
  • Reply to Moggy

    Yes I agree. Where would we be without Mark's expert help ?
  • edited October 2019
    So I took the plunge .

    I put the Cheetah on the DK Issue 2 16K ZX Spectrum and on the back of that I put my cased up v2 Retroleum Smart card . On pwer up it made nice beeping noises . Although there was some distortion of the graphics I could read enough to see "Lower RAM error at 57FFB " And "32K Upper Ram OK" ( I think this means the Cheetah is OK) .Then it said "Lower Ram error encountered ". Two of the ICs mentioned IC3 ,IC4 were listed in the lower middle right of screen.

    IC6 ,IC7 ,IC8 ,IC9 ,IC10 ,IC11 ,IC12 ,IC13 were also listed on the left hand side of screen ,well left of those two ICs. I was not sure if it was listing all of them as faulty or just IC3 and IC4.Still I reckon the Smart card "did good" .And I am pleased about the Cheetah.(It is not a "dirt rotten cheetah" after all)

    Post edited by harriusherbartio on
  • edited October 2019
    moggy wrote: »
    Now I have seen the capacitor leakage in the ZX81 Rampak ,I think I will check the Cheetah Zx Spectrum Rampack for leakage as well .

    Please do not use the ZX81 RAM pack if it has leaking capacitors as you can easily damage the ULA chip or cause some other damage.

    Hopefully 1024MAK will see this and offer advice on how to repair it.
    I find his advice well worth listening to and in my opinion he's the most knowledgeable guy for all things 81 and explains things in an easy to understand way.

    Yes, if you want to save it (the ZX81 RAM pack), some work is needed. Don’t power it up until all the electrolytic capacitors have been renewed and the circuitry for the DC/DC inverter has been inspected, checked and tested.

    Oh, and this thread is NOT an WOS Update, so is in the wrong place :-(

    Mark
    Post edited by 1024MAK on
  • Yes sorry Mark
    My enthusiasm got the get of me and I put it in the wrong place again! .

    Re ZX81 Ram pack . Now I have 2 possibilities :-1) The varnish appears to be genuine 2) A lot of grime was removed when I cleaned it with alcohol - brownish . I do not think alcohol can dissolve varnish so it is possible that there was capacitor discharge as well as varnish So I will replace the caps at some point and will not charge it up till then . Thanks one again for the advice..
  • edited October 2019
    Post edited by harriusherbartio on
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