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Simon Carter

Dead 65XE, keyboard membranes

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Hi,

   usual question asking again - just bought an untested 65XE from eBay (listed as untested) and sadly it didn't surprise me by working 🙂 I've tried the keyboard on my working XE and that's just a membrane clean/replace, so no biggie there, but turned the unit on just gives a red/burgundy screen, nothing else. Am I looking at dead RAM, or potentially replacing every IC until something works?

 

On the plus side, i did get a copy of Yogi and the Greed Monster, so it's not all bad 🙂

 

Si

 

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Personally I would replace the ram first, I bet its MT ram which if it hasn't failed will do soon 😈

Then see where you go from there

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RAM says Sharp, not sure if that's the same as MT. Quite looking forward to seeing if I can resurrect this one

 

Thanks

 

 

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@Simon Carter

 

Good luck. You may already know this but bare in mind with the mylar/membrane you get dual and single layer ones. 

 

AFAIK and in my experience dual layer XE keyboards have lots of loose little blue rubber popper type things which all fall out upon dissasembly if you have the keyboard the wrong way. (Sorry, I don't have a pic to hand).

Simius sells the dual ones for a very reasonable price if you PM him.

 

Whereas single layer mylar/membrane XE keyboards have fixed black rubber contacts , like this when you open it up. These don't fall out:

 

image.png.eed59f47eddeca1d79cb0e2353684c72.png

 

Reason I know is I have both types of XE keyboard.

 

As mimo mentioned the red/burgandy screen is very likely a bad ram chip or maybe more. I've not heard bad things about the Sharp brand of ram chips generally.

 

I recently ressurected a 130XE from the dead, (a rather lengthy post here details it all which may help). Plus I did the same with a 600XL with a few issues included bad ram, (red/burgandy screen).  Again detailed in a rather lengthy post here

 

Worth bearing in mind both my machines had multiple issues aside bad ram - and yours still might. But at the start in both cases it was bad ram chips initially, (with other issues then becoming apparent). I've found, (as many other's have), that you have to fix one thing before you can work out what else needs fixing.

 

The only PITA thing is all the RAM chips and others on the XE board are socketed. 

 

EDIT: If you haven't done already make sure you aren't using a notorious Ingot power supply to power up the XE, and IHMO get yourself a 5v USB to 5pin DIN power supply (in UK on Ebay they cost £10).

 

 

 

 

 

 

Edited by Beeblebrox

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yeah red screen can indicate bad RAM, OS ROM, CPU, MMU. RAM is easiest to check by using the piggyback technique or by using a Sys-Check-II device - bought from user TF_HH. There are many forum topics that go into greater detail.

just to set Beeblebrox straight, the European ingot power supplies are fine, its the USA ones that are moody.

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40 minutes ago, xrbrevin said:

just to set Beeblebrox straight, the European ingot power supplies are fine, its the USA ones that are moody.

@xrbrevin  ah, I did not know that. Thanks. :thumbsup:

  • Like 1

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I'm not knowledgeable enough to know the answer to this but I have only ever seen Mt ram in a 65xe.

Is there any evidence of it being replaced at some point? Maybe it wasn't done very well?

 

And if you need a double layer mylar I can highly recommend the ones made by dudie of this parish.

Good luck with the fixin' looking forward to following progress 

 

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ps just realised a typo in my post (#4) above which I now can't edit. I meant to type:

 

The only PITA thing is all the RAM chips and others on the XE board are NOT socketed. 

Edited by Beeblebrox

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5 hours ago, mimo said:

I'm not knowledgeable enough to know the answer to this but I have only ever seen Mt ram in a 65xe.

Is there any evidence of it being replaced at some point? Maybe it wasn't done very well?

 

And if you need a double layer mylar I can highly recommend the ones made by dudie of this parish.

Good luck with the fixin' looking forward to following progress 

 

 

MT RAM is definitely used in a lot more machines than just a 65XE. I think it was used a lot in all XL/XE machines. I have at least one 800XL with MT RAM.

 

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if you end up with the wrong type of membrane, there are workarounds - one is to add an M3 washer behind each rubber plunger or the other is to insert a small grub screw into each plastic plunger. depending on type

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4 minutes ago, xrbrevin said:

if you end up with the wrong type of membrane, there are workarounds - one is to add an M3 washer behind each rubber plunger or the other is to insert a small grub screw into each plastic plunger. depending on type

@xrbrevin Funnily enough the 7mm OD m3 plastic washer trick is exactly what I did with my dual mylar/membrane and the single type keyboard. (Simius put me onto it). The only thing it does is make the key press feel stunted as the keys lose a couple of mm of down movement. Guess it's worth getting thinner washers next time round. It took around 20mins to install them and what really helped was a curved set of electrician's tweezers. 

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29 minutes ago, bfollowell said:

 

MT RAM is definitely used in a lot more machines than just a 65XE. I think it was used a lot in all XL/XE machines. I have at least one 800XL with MT RAM.

 

I may have miss worded that.

I have not seen sharp ram in an XE before, I have definitely seen Mt ram in a 800xl 

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4 minutes ago, Beeblebrox said:

It took around 20mins to install them

  nice, it takes patience for sure!

and still superior to the original weak mylar 😎

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What kind of 65XE do you have in your hands? If it is one with ECI, it is great since there are just 2 RAM chips to change, very easy, as you can just cut the feet of the chips and then desolder each pin separately. Also a good thing is that Syscheck can be used with those machines. Not only that, you can transform that machine in a 130xe easily if you can find an EMMU chip.

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17 minutes ago, xrbrevin said:

  nice, it takes patience for sure!

and still superior to the original weak mylar 😎

True. The mylars Simius sold me are quality and less costly than the other XE ones I've seen.

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Wow, 

      So many answers, thanks guys. First things first:

 

20211027_094943.thumb.jpg.f6127a7a557678bd0e1be2b7d3112cf8.jpg

 

 

Definitely says Sharp! I have Sharp RAM in both my 65XEs. I was going to ask if its possible to convert a 65 into a 130 with extra RAM and an MMU but @manterola already seems to have answered that one.

 

I had replaced the membrane in my first 65XE, and had made the error of choosing the wrong type, but fixed it with washers as @xrbrevin suggested, does seem to have made the keyboard less responsive though 😞. I think I'll pick up a proper membrane when I have the funds.

 

Re the ingot power supplies - I thought the UK ones were just as bad as the US ones? Apparently not, although I'm sure one killed my 800XL...

 

Looking forward to getting some RAM and having a stab at fixing the XL and the XE. Slowly regrowing my childhood collection:

 

20211027_100255.thumb.jpg.36882199078efd70fadb1888be1bd6a3.jpg

 

And yes, the dressing gown is mine...

 

Regards

 

Si

 

 

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22 minutes ago, Simon Carter said:

to convert a 65 into a 130

aside from the extra RAM chips you will need a 74LS95 for U35 and a programmed GAL16V8D for U34

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3 hours ago, xrbrevin said:

aside from the extra RAM chips you will need a 74LS95 for U35 and a programmed GAL16V8D for U34

Or the emmu CO25953, very hard to find nowadays.

However, I have never done that ram expansion myself in that motherboard version. I did it in a motherboard that uses 4464 RAM chips, so I needed to add the emmu and 2 4464 chips, nothing else. 

Edited by manterola

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18 hours ago, manterola said:

What kind of 65XE do you have in your hands? If it is one with ECI, it is great since there are just 2 RAM chips to change, very easy, as you can just cut the feet of the chips and then desolder each pin separately. Also a good thing is that Syscheck can be used with those machines. Not only that, you can transform that machine in a 130xe easily if you can find an EMMU chip.

This was something else I meant to ask - both my XEs have the ECI bus, but also have 8x8k RAM. Only have two to check/change would make things a lot easier...

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56 minutes ago, Simon Carter said:

This was something else I meant to ask - both my XEs have the ECI bus, but also have 8x8k RAM. Only have two to check/change would make things a lot easier...

Yep most European 65xe's used the 130xe boards with only half the ram populated , but with the eci port 

Edited by mimo
Fixed it

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1 hour ago, Beeblebrox said:

@Simon Carter  I wonder if you could post a photo of the entire 65XE's PCB? :grin:

20211027_215717.thumb.jpg.bf27be013cae19ad4c31480b3952811d.jpg

 

Here you go...

 

If you need more detail, just shout, wont be til tomorrow though

  • Thanks 1

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Well, I've just picked up some RAM chips and tried piggybacking but no change, I did notice that, at some point, a previous owner has socketed the Freddie chip, I wondered whether this had failed previously. Might be an avenue to explore...

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