fabrice montupet Posted November 4, 2017 Share Posted November 4, 2017 (edited) Tonight, I undertook the internal cleaning of a perfectly functional TI-99/4A that I had bought a few years ago, to do the maintenance of it as I do for all my equipment in a cyclical way. During the disassembling, I could see that the TI employees not employed half-measures with the thermal paste for the VDP ... It was dropped everywhere on the legs of the component, on the IC support and even on some neighboring components. To simplify the cleaning of the quartz that was also covered (the paste having hardened over the years), I decided to desolder it. At this time, I wondered what could be the supplier of this quartz, this quartz of 10.738635 MHz that equips all TI-99/4A and which runs the VDP. The plastic film wrapping it indicating only this frequency of 10.738635 MHz, I used a X-Acto cutter to remove the film, hoping that an inscription engraved on the quartz would tell me more.And indeed I could discover the name of the manufacturer: NDK. But what was my surprise by reading the frequency: 8.867 MHz! A packaging marking error. The VDP can't work at this frequency, it looses the video sync. Edited November 4, 2017 by fabrice montupet 2 Quote Link to comment Share on other sites More sharing options...
+Vorticon Posted November 4, 2017 Share Posted November 4, 2017 Interesting find. Even more interesting is the fact that you take apart perfectly functional vintage equipment 4 Quote Link to comment Share on other sites More sharing options...
kl99 Posted November 5, 2017 Share Posted November 5, 2017 Tonight, I undertook the internal cleaning of a perfectly functional TI-99/4A that I had bought a few years ago, to do the maintenance of it as I do for all my equipment in a cyclical way. During the disassembling, I could see that the TI employees not employed half-measures with the thermal paste for the VDP ... It was dropped everywhere on the legs of the component, on the IC support and even on some neighboring components. To simplify the cleaning of the quartz that was also covered (the paste having hardened over the years), I decided to desolder it. At this time, I wondered what could be the supplier of this quartz, this quartz of 10.738635 MHz that equips all TI-99/4A and which runs the VDP. The plastic film wrapping it indicating only this frequency of 10.738635 MHz, I used a X-Acto cutter to remove the film, hoping that an inscription engraved on the quartz would tell me more. And indeed I could discover the name of the manufacturer: NDK. But what was my surprise by reading the frequency: 8.867 MHz! A packaging marking error. The VDP can't work at this frequency, it looses the video sync. Is the quartz identical for 99/4A NTSC and 99/4A PAL? Quote Link to comment Share on other sites More sharing options...
fabrice montupet Posted November 5, 2017 Author Share Posted November 5, 2017 Yes, they are. To convert a US 99/4A to an EU 99/4A and vice-versa , you just have to replace the VDP, the DIN connector and make some minor modifications on the motherboard (straps/resistors) :-) Quote Link to comment Share on other sites More sharing options...
kl99 Posted November 6, 2017 Share Posted November 6, 2017 I am curious, did you choose to switch your 99/8 VDP in order to use a YPrPb output like Jens-Eike did modify his 99/8? I am not really satisfied with the NTSC Composite output. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.