Marius Posted February 12, 2014 Share Posted February 12, 2014 The XEGS I bought today is missing a MOBO switch (see other topic) but I also saw a modification on the sound amplifier. What is that thingy doing there? The only thing that I can think of is that this diode prevents damage in case of incoming sound on the cinch connectors of the computer. But I guess someone else might know it. I had to break the warranty seal so I guess this was a factory-mod Quote Link to comment Share on other sites More sharing options...
Rybags Posted February 13, 2014 Share Posted February 13, 2014 XEGS doesn't use an amplifier IC - that IC in the middle is a 555 Timer IC, it's used to generate the poweron Reset signal for 6502 and other major chips. Quote Link to comment Share on other sites More sharing options...
re-atari Posted February 13, 2014 Share Posted February 13, 2014 (edited) The XEGS I bought today is missing a MOBO switch (see other topic) but I also saw a modification on the sound amplifier. What is that thingy doing there? The only thing that I can think of is that this diode prevents damage in case of incoming sound on the cinch connectors of the computer. I had to break the warranty seal so I guess this was a factory-mod Look at the amount of resin flux on the PCB, Atari's 'betere bak- en braadwerk'... The diode is probably used to improve the 555's stability. re-atari Edited February 13, 2014 by re-atari Quote Link to comment Share on other sites More sharing options...
Marius Posted February 13, 2014 Author Share Posted February 13, 2014 Whaha yes. I call that also 'bakken' (of metselen). Quote Link to comment Share on other sites More sharing options...
re-atari Posted February 14, 2014 Share Posted February 14, 2014 (edited) Whaha yes. I call that also 'bakken' (of metselen). But to compensate things, judging by the lousy state of the solder joints it looks like the Tramiels cut back on the amount of solder used at assembly. I can see a resistor that is just barely soldered in. Look after the pennies and the pounds will look after themselves, right? Thank God Atari did not use leadfree solder back then, production would have had just about 100% DOA. Even nowadays leadfree solder is a real pig to work with (speaking from experience). re-atari Edited February 14, 2014 by re-atari Quote Link to comment Share on other sites More sharing options...
Rybags Posted February 14, 2014 Share Posted February 14, 2014 Judging by the flux mess, I very much doubt it's OEM - looks like something someone has done at a later point. Probably just before getting a phone call and rushing off somewhere and leaving it to sit for the remainder of the weekend. Quote Link to comment Share on other sites More sharing options...
re-atari Posted February 15, 2014 Share Posted February 15, 2014 Judging by the flux mess, I very much doubt it's OEM - looks like something someone has done at a later point. Probably just before getting a phone call and rushing off somewhere and leaving it to sit for the remainder of the weekend.I agree it looks like very homebrew, but the factory seal would have been damaged when opened by (one of the) previous owner(s). I guess it's possible to remove the warranty seal without entirely breaking it, but you'd still be able to tell it was peeled off (again speaking from own experience). BTW, after checking the 555's datasheet, it looks like the diode has to be a zener type, used to protect its TRIG input. And ultimately improve stability (as I mentioned). re-atari Quote Link to comment Share on other sites More sharing options...
Rybags Posted February 15, 2014 Share Posted February 15, 2014 I overlooked the seal thing. I suppose given that some XEs have mysterious socketed random chips and the general theory is that failed machines have sockets put in for the replacement ICs that possibly this one didn't pass and had a rushed production line fix job. Quote Link to comment Share on other sites More sharing options...
Marius Posted February 15, 2014 Author Share Posted February 15, 2014 Yes. It was perfectly sealed. The seal did look like factory-new. It is a Rev. 3 motherboard of the XEGS by the way. I have a few more XEGS's floating around here, and the others all do have a Rev. 1 motherboard. In the REV. 1 motherboard there are more chips on socket, but the diode is not there. I love the XEGS. It's a nice computer. The keyboard quality s*cks bigtime. From all XE keyboards, the XEGS keyboards give the most terrible typing-experience EVER. But I replaced one now with a better one, and it's really cool. My 5 year old daughter loves the colorful buttons, and I love the default video output quality. Quote Link to comment Share on other sites More sharing options...
re-atari Posted February 15, 2014 Share Posted February 15, 2014 Yes. It was perfectly sealed. The seal did look like factory-new. It is a Rev. 3 motherboard of the XEGS by the way. I have a few more XEGS's floating around here, and the others all do have a Rev. 1 motherboard. In the REV. 1 motherboard there are more chips on socket, but the diode is not there. I love the XEGS. It's a nice computer. The keyboard quality s*cks bigtime. From all XE keyboards, the XEGS keyboards give the most terrible typing-experience EVER. But I replaced one now with a better one, and it's really cool. My 5 year old daughter loves the colorful buttons, and I love the default video output quality. Goes to show that after a few decades old stuff gets 'hot' again, even the 'Miami Vice' colors Atari used on the XEGS's buttons re-atari Quote Link to comment Share on other sites More sharing options...
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