Sinclair ZX80 / ZX81 / Z88 Forums

I didn't tweak any values before burning. Unless you get consistent failure with one type of EPROM t then leave well alone. I left it at the defaults for the ST 27C64 Chips, and it works perfectly, but the (Intel?) 27128A I was doing for another retro device is a different matter. I thought I had a...

I had a TOP853 and it worked.... I finally got around to picking up a EPROM burner, made a new ROM and the ZXpander is up and working again! I ended up picking up the Top853. I bought it on eBay cheap ($35 USD), but it took forever to ship from China, and the English translation reads like it was f...

Oh rats... AFK and missed it. Are you going to do another run at some point?

... My low-end Wellon has what I consider to be more reliable, less buggy code driving it, and a raft of recommendations from some people I trust I've seen the Wellon VP-190 on eBay, which seems to be the least expensive Wellon programmer that I've found so far. it costs about twice as much as the ...

Could anyone recommend a good, not to expensive, EPROM programmer? I've been seeing the TOP853 and G540 universal programmers a lot on ebay, they're cheapish... any thoughts?

questarian wrote:... I'm going to try cleaning and buffing the pins to see if that makes a difference.

Nope...Well, It was a nice theory while it lasted
-John-

Thanks! It occurred to me last night that the problem with the ROM might also be a oxide/contaminant coating on the pins and/or socket. I've experienced the same on-again off-again behaviour before so I'm going to try cleaning and buffing the pins to see if that makes a difference. I don't have a RO...

When My new hardware arrived today I decided to swap out the v6.6 ROM from my DOA board with the V6 on the working board I had so that my two working ZXpanders would both be running the same new versions... but when I swapped the ROM, the second one stopped working!!!!! For a moment I really thought...

Excellent ! I'd be interested in at least 2 as well!

I've swapped the chips between the two of them several times, with and without the SD, I've looked cold solder joints and bridges.... I'm reluctant to do more swapping as I've bent pins a number of times and I expect that if I do much more they'll begin breaking off. I ran a meter on the regulators ...