memory address error 00000, 04 PCXT Vtech laser xt/3

[Robin4]

I changed the memory on my Vtech laser xt/3 because had earlier a parity error.

But now i have got 2 problems.

1. I have installed new memory on the 2 inside rows (removed all older), which should give me a total of 512KB if i set sw1 and lever 3 to ON. (didnt installed the optional 128KB memory yet due troubleshooting. that four x 64x4 and two 64x1 parity.

2. I should have 512KB memory installed, but the system now only sees 64KB

3. Also got a memory address error on 00000, 04.. But dont know where this IC is located. Behorehand i tested all the memory chips with the DIY CHRIS 4164/41256 Dram tester from ebay. But this tester, tested all the chips as good..

 

[3pcedev]

Probably dumb question, but is the speed rating of the new RAM 150nS or faster?

Failing that try a different sequence of ram chips in the sockets and see if the address error changes.

 

[Robin4]

Yes they are all 120nS because there is 12 written on them.

Its not very easy to get the chips out because of the disc capacitor are in the way. (stupid design)

 

[Robin4]

I have fixed it.

There was two 64 x 1 chips installed between the other 256k x 1 chips. How this happend? I looked at the date code and not at the size of the chips. 512KB seems working now. Parity is on.

Only have to wait for the upgrade to 640KB.. Had them ordered few days ago.