![]() On the TI, only a percentage of consoles have a Mitsumi. No doubt the market for such things is larger for the still-popular Sinclair family. Less likely than the Mitsumi to get dirt on the contacts since the layers are sealed together.įor the TI99/4A, a Mitsumi membrane would require just a single layer with a separator since the circuit board provides the second contact "layer." Installation would likely be more involved. It's a three-layer sandwich two contact layers with a separator between, with many punched alignment holes. I paid around $24 for one to fit my TS1500. The replacements are well made, sold out of the UK and cost with mailing is reasonable. Good thing, since the original membrane is pretty much doomed to fail at some point and nearly all the different models used them. There's new replacement membranes made to fit the Sinclair Spectrum, ZX81 and Timex TS1000 and TS1500. ![]() ![]() I sell blank pcb and also assembled adapters at look under ti hardware and keyboard ![]() Usb is standard usb keyboard interface yes it works fine with wireless keyboards That is short of finding an Alps that is obviously broken, then I would need another for some switches for parts. I am not sure how I would reliablly be able to tell between it and the Alps model on an ebay listing. It doesn't sound like they are a great design either. It seems though they have what is called a "Stackpole" keyboard, I am seeing a number of 99/4as for sale with a missing key or so which are of that type. I will keep an eye out for an Alps keyboard. I would rather have a working keyboard on the computer if I can. The USB adapter there is to setup input to the TI from a modern usb keyboard then? Indicating even a wireless one. It has been a month or more since I pulled the keyboard apart, I am not sure if it would be practical to attempt that. I am the most tempted by coming up with a replacement board, switching it over to some microswitches. I repurposed a couple for use on my Timex TS1000 by cutting some board traces and adding some flying leads. The key matrix isn't that hard to figure out with a schematic on hand. I've sold a couple like this for cheap where the known good keyboard was the best part of the deal.Īrcade Shopper sells a USB adapter, also you could roll the dice for another Mitsumi which he offers as-is and hope to get a working one. Or hunt down a non-working console with an Alps. Too long ago now to remember.īut somebody on here has gotta have a stash, ya'd think. If I still have any left, they're buried in the shed somewhere and may be the duds I pulled and replaced. and you wouldn't need to power up the disassembled console to test.įor some years after TI bowed out, you could find good Alps keyboards in surplus for $5 each. Such fun! Or a DMM on Ohms should show the contact failing/making/failing. Touch the jumper to the second contact and pretend you're the keyswitch. You could jumper the keyboard connector at those points to check the motherboard side of things. The other types can get dirty or break a solder joint, but at least that's easily dealt with. I've never seen console-related key-input issues, always been the keyboard. I would almost design a pcb replacement, except the stems don't have the conductive pads on the bottom, and the springs are setup differently and wouldn't work.įrom what I read, I take it the multi keystrokes are likely "poor" condition contacts barely making contact, and sort of making it like it is bouncing? Being wired directly to the cpu inputs, it shouldn't be a circuity issue then? It is sad that it is so similar to the Commodore 64, except spring placement and being membrane. I was very disappointed to find this unit had the Mitsumi. I am not yet happy enough with the 99/4a to invest another likely $75.00 to hope to get a good Alps keyboard, or least one that is repairable. I'll likely attempt it at some point, but I am not expecting amazing long term results. I wanted to see if there was some reliable method found here. I haven't heard of any of the old vintage Mylar keyboards being properly repairable. ![]() I was not impressed with the likelihood of a fix, or at least a long term one. I should have noted that I have seen the Mylar fix post. ![]()
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