16K RAM pack

[sP1d3r]

I've started on the conversion by desoldering the ram chips, one of which was faulty unfortunately so the ram pack wouldn't have worked.
They came out quite easily also I removed the LS157's near the connector, one of which had been replaced to check it (worked) and the other which will be turned into a 4-chip stack, more fiddly to get them out as they're close to the connector.
I've desoldered the cable and currently hope to replace it with M&F pin headers for ease of soldering and assembly/disassembly.
The pin headers fit OK in the case and there's enough room for the quad stack using the 100uf capacitor purely as a spacer.
During the conversion it's possible to test as a 16K RAM pack with 5V DRAMs so I'll post again then.

Pin headers fitted as a rough guide

Solder side

Component side

[sP1d3r]

I bought a batch of 20 128-cycle refresh NEC D4164C-15 DRAMs from a vendor on Aliexpress and I've tested them with my Retro Chip Tester and also with my 1-bit DRAM tester by Simon Raybould, which I bought from eBay

Whilst all but one of the chips passed the 1-bit tests, only 4 of the chips passed the RCTP 4164 tests without using the decoupling capacitor.
A further 6 passed without the decoupling capacitor after testing with the 1-bit tester a few times and then retrying on the RCTP, the rest failed the rnd 2 test.

With the decoupling capacitor in circuit, all but one of the DRAMs passed on the RCTP so this might be down to my USB power supply.
It may be the case that with a good linear PSU the chips would pass the RCTP 4164 tests without the decoupling capacitor in circuit, I may try to test via the barrel connector with a linear (Class A transistor) PSU to see if this affect the results.

It would seem that the chips I bought are OK to use for the 64K conversion so I'll have a go at this.

The difficult part of this is soldering a stack of 4-chips via the 5V and GND legs and with an array of 1N4148 diodes soldered to various legs of the chips in the stack.
I'll have a go at this soon

[sP1d3r]

Since I've got 2 of my Zeddy's working I've tested the first 1016 RAM pack and it works OK, I'll be trying the 64K mod with the second one soon.

Working TS1016 16K RAM pack