Faulty CZ1016 Rampack

[bola_dor]

Well. In fact it is a Sinclair Issue 2 rampack inside that was rebranded and sold in Argentina ...
It is my original almost 35 years old rampack but is not working..
Voltages rails on the 4116s are ok.
Pin 2 to 14 have continuity in all of the ram IC..
Pin 2 to all of the corners (0v, -5v, +5v, +12v) have no continuity on any of them .. some current is measured but about 1700ohm over +12v for example..
And no continuity between pins 2 either...
I am waiting a lot of 4164s I bought from china to replace them but now I think that there may be another problem..
Thanks

[Paul]

Please post a photo of your Rampack PCB. It makes it much easier to determine which PCB version it is.
Kind regards
Paul

[bola_dor]

Please post a photo of your Rampack PCB. It makes it much easier to determine which PCB version it is.
Kind regards
Paul

Hi Paul,
Is exactly like this one posted here..
I may take my own pictures later
Than you

https://www.sinclairzxworld.com/viewtop ... 340#p24322

[Paul]

You already got some hints in the linked thread
Are all PCB interconnects still reliable? Mine always break at opening the case

[bola_dor]

You already got some hints in the linked thread
Are all PCB interconnects still reliable? Mine always break at opening the case

Yes, in fact I resoldered a new ribbon cable and retested it all the points with a multimeter

[1024MAK]

With RAM packs, these can be a right pain to fault find. One method is to put an adapter in between the computer and the RAM pack so that (1) the computer’s internal memory is not disabled, and (2) the RAM pack is remapped to a different area of memory.

This adapter normally needs a male edge-connector (PCB) and an edge-connector socket. But it is possible to use sellotape to insulate selected edge-connector contacts on the computer. Then use temporary wires and a simple circuit to reroute some signals.

Then it is possible to use BASIC to write and read test data to the RAM pack.

Alternatively, if you have an oscilloscope or logic analyser, these tools can help to ‘see’ what’s going on with the signals.

Mark

[bola_dor]

With RAM packs, these can be a right pain to fault find. One method is to put an adapter in between the computer and the RAM pack so that (1) the computer’s internal memory is not disabled, and (2) the RAM pack is remapped to a different area of memory.

This adapter normally needs a male edge-connector (PCB) and an edge-connector socket. But it is possible to use sellotape to insulate selected edge-connector contacts on the computer. Then use temporary wires and a simple circuit to reroute some signals.

Then it is possible to use BASIC to write and read test data to the RAM pack.

Alternatively, if you have an oscilloscope or logic analyser, these tools can help to ‘see’ what’s going on with the signals.

Mark

Thank you..
I can get an oscilloscope but I I really don't know what to check for..
That interface sounds interesting.. where can I find it. ?
Regards

[1024MAK]

Repairing RAM packs, other useful threads: here and here.

There are no ready made adapters or kits for an adapter, but there are details of the circuitry in this thread. Do read it all the way through, as a diode is needed that is not shown in the first diagram.

An oscilloscope will enable you to see the input and output signals of each DRAM chip. It can also be used to see if select, enable and other control signals are present.

Mark

[bola_dor]

Repairing RAM packs, other useful threads: here and here.

There are no ready made adapters or kits for an adapter, but there are details of the circuitry in this thread. Do read it all the way through, as a diode is needed that is not shown in the first diagram.

An oscilloscope will enable you to see the input and output signals of each DRAM chip. It can also be used to see if select, enable and other control signals are present.

Mark

Great.. thank you!!!