Options for 130XE Memory Chip Replacement?

[800_Rocks]

I have a 130XE that boots straight to the memory test and shows all red and some orange (instead of green).  Before I unsolder, socket and replace the 16 memory chips I wanted to ask if there are other memory options for the 130XE.  Questions:

1) Could I just install an Ultimate 1MB upgrade?  OR does U1MB require the underlying default 64K (or 128K) to be available and functioning?

2) I see the '64k SRAM Module for XL/XE' upgrade on The Brewing Company site.  Could I use this to get to 64K of RAM and just leave my faulty RAM on the board?  Obviously this would only give me 64K rather than 128K but then I suppose U1MB could be installed.

3) Other options short of replacing the original 16 memory chips?

 

 

[mimo]

@tf_hh makes a 576k SRAM upgrade for the 600xl which includes the 64k base RAM.

From what I read you should be able to use this in an XE.

Or the syscheck board , again from tf_hh, plugs in to the eci(?) Port on an XE and takes over ram , plus all sorts of other goodness

Edited March 5, 2021 by mimo

[+Nezgar]

First order of business.... Swap one end of the two resistors on R110/R111 to swap the base 64K U13-and extended 64K (U26-U33).

 

The machine may then boot up OK if the extended RAM is OK (now being used as base RAM)

 

Otherwise if you either buy a SysCheck 2.2 (which has a memory test OS ROM as one of the selectable OS's) or socket your OS ROM and temporarily replace it with Shoestring's memory tester, you can find out which base RAM chips are specifically at fault.

 

Although the general recommendation with "Mt" brand chips is to replace them all - they are a very common failure point in XE's. Others will likely eventually fail even if you replace some individual bad ones...

 

[_The Doctor__]

first order of business check the power supply under load right away then 15 minutes later...

then see the above post by Nezgar...

 

1) it's best to repair the on board memory then do other upgrades, shorted or ranbom chips do weird things...

2) see 1)

3) yes there are many available from sram to simm type upgrades... to replace what's on board..

 

after you have the base memory working u1m etc. are a fine way to go.

Edited March 5, 2021 by _The Doctor__

[+Stephen]

My take on this.  MT chips are the worst out there.  If all 16 are not bad now, they will be soon.  U1MB is a fantastic upgrade, but it does require a machine with a working base 64kB of RAM.  Given that the old RAM is not worth saving, and XE PCBs are notoriously fragile, it would be in your best interest to cut RAM out and de-solder the pins one at a time, then install sockets.

[ClausB]

I'm betting the bad chip is the one with the big, red X on it!

Edited March 6, 2021 by ClausB
Oops, wrong photo.

[800_Rocks]

Notice my upper-left memory chip is 4164 all the others are 4264.  Are these interchangeable?  When I replace all the chips which do I want (4164 or 4264)?  and does it matter if I replace with 15 or 20 speed chips.  I notice my board also has a mix of both speeds.

Edited March 6, 2021 by 800_Rocks
added picture

[_The Doctor__]

The 4164 that often appear in the first spot on the XE pcb does not require the 100uS pause and 8 ras cycle initialization the 4264 does.

The 4164 also dissipates a little more power than the 4264 chips do and tolerates a bit more stress than the 4264's do.

This is why the 4164 is in that position, it is first in line for power to hit it and it is first in line for access.

Somewhere in the AA threads this or something similar has been noted along with folks discussing why some machines take so long to power cycle and reset and all that other good stuff.

It is good to choose memory of the same access time, you have a mix of 150 to 200 as your machine stands now... I'd just toss 150 (-15) in it and call it a day.

This is of course from my flawed and failing memory (is my brain MT?)... check your datasheets and see if I'm still pretty close on it.

Edited March 6, 2021 by _The Doctor__
editted to add empty (mt) brain joke. LOL

[Sinjinhawke]

When I got my 130xe it has a very similar memory config.  One high quality chip in the first slot and MT crap in all the others. I wasn't showing failures on the built in RAM Test but the extended RAM was showing almost all failures. 

 

I bought a soldering iron, some sockets, a bunch of Tesla 4164 memory chips (ebay) and got to work doing a horrible rookie job of removing just the 8 on the right side and putting in sockets.  I broke one of the capacitors while removing the old memory so ordered hundreds of those to replace 1.  I put the 8 Tesla chips in the sockets and they all test perfect.

 

I am holding off replacing the first row until I see signs of failure.  I think I have more practice now and will do a better job next time though.