GDMike Posted October 31, 2023 Share Posted October 31, 2023 On 8/29/2022 at 10:07 AM, FarmerPotato said: Welcome! TIPC is welcome here—where else are you going to find fans? (I used one in 1985). I haven't bid on any as I usually look for machines that have a solid price on them and if they're reasonable then i'll take a gander at it. Quote Link to comment Share on other sites More sharing options...
InfiniteTape Posted October 31, 2023 Share Posted October 31, 2023 23 minutes ago, GDMike said: TIPC power supply started sparking without failing. I found a replacement for this part. Notice the prong coming off the top fuse holder pin touching component. . A Rifa cap? I've never owned an Apple II in my life, but I've seen enough repair videos to know that those should generally be replaced on sight. 3 Quote Link to comment Share on other sites More sharing options...
GDMike Posted October 31, 2023 Share Posted October 31, 2023 1 hour ago, InfiniteTape said: A Rifa cap? I've never owned an Apple II in my life, but I've seen enough repair videos to know that those should generally be replaced on sight. It's inside the TI power supply I have. I read something about the ps being similar to an apple supply, but the article could not verify the power was the same on 4 pinouts to the main board. 1 Quote Link to comment Share on other sites More sharing options...
GDMike Posted October 31, 2023 Share Posted October 31, 2023 I wanted to add an 8087 coprocessor. Any links to a good one? Quote Link to comment Share on other sites More sharing options...
Stuart Posted October 31, 2023 Share Posted October 31, 2023 A RIFA capacitor started smoking - that is a surprise! Is that a second one at the other end of the fuse - replace that one as well if so. 1 1 Quote Link to comment Share on other sites More sharing options...
GDMike Posted October 31, 2023 Share Posted October 31, 2023 22 minutes ago, Stuart said: A RIFA capacitor started smoking - that is a surprise! Is that a second one at the other end of the fuse - replace that one as well if so. Oh? I didn't notice.. but I'll double check. Thx Quote Link to comment Share on other sites More sharing options...
GDMike Posted October 31, 2023 Share Posted October 31, 2023 I started looking into the 8087 co, and it looks like a couple years ago the minds(K,C&S),of the 8087, that mr. Kahan did an interview and it's on YouTube. He speaks a little bit on his work with HP back in the day for calculators and tells some differences between TI calculator algorithm and his. He also talks about today's debugging of code is almost impossible. 1 Quote Link to comment Share on other sites More sharing options...
GDMike Posted October 31, 2023 Share Posted October 31, 2023 (edited) 1 hour ago, GDMike said: Oh? I didn't notice.. but I'll double check. Thx Ok... It looks like it is just a different value and there's two of them. I'll have to try to figure out the values and see if I can get parts thanks so much for checking into that for me you may have just saved me a fire. I took a photo of T2(transformer ),I'm not sure what that does or if it's any good it looks like it's been cooked Edited November 1, 2023 by GDMike 1 Quote Link to comment Share on other sites More sharing options...
+FarmerPotato Posted November 1, 2023 Share Posted November 1, 2023 3 hours ago, GDMike said: Ok... It looks like it is just a different value and there's two of them. I'll have to try to figure out the values and see if I can get parts thanks so much for checking into that for me you may have just saved me a fire. I took a photo of T2(transformer ),I'm not sure what that does or if it's any good it looks like it's been cooked I replaced two RIFA caps in the TI-928 terminal (1988). Got the equivalent Kemet from Mouser and for one the part number was unchanged. Read both sides of the cap for clues. Here's a post I read about safety capacitors: https://www.eevblog.com/forum/repair/x-and-y-capacitor-replacement-rifa-etc/ 2 Quote Link to comment Share on other sites More sharing options...
+FarmerPotato Posted November 1, 2023 Share Posted November 1, 2023 @GDMike Can you clarify what's going on with the fuse? 1. Is the fuse blown? 2. You mentioned that the fuse holder touches the RIFA cap--is that only after the cap exploded? 3. Is the cap itself now shorted, or not? (I'm curious if it fails open or fails closed) Quote Link to comment Share on other sites More sharing options...
GDMike Posted November 1, 2023 Share Posted November 1, 2023 (edited) I noticed a tab at the fuse holder which is part of the fuse holder itself and because of its little corner ear it was extended over into that capacitor by default install and It was a simple bend of the ear to put it back out of the way, but it was pretty sloppy of whoever put those fuse holders in not to see that. That would have been just a matter of time before the fuse holder actually pinched the paper of the capacitor. No the fuse never blew but I was quick on the power switch anyway I powered it up as a test computer booted and then The slight smell of smoke started and I killed the power. I pulled the power supply cover off looking for a dirt buildup I was thinking I would find but I didn't see much so I went ahead and powered up again and then the arcing was there and again the computer was booting but I killed it and then pulled the power supply completely off. When I investigated the power supply it was easy to see the capacitor was split in half, this particular brand is made of rice paper I think and of course the smell is horrendous. YouTube has many videos on this I found interesting, as I never knew. And since my postings I've been made aware that there are two more of those capacitors in my power supply and need to replacing and of course I've got to go back to the other computer that I have and pull that power supply off and replace those too. Not sure of the cap being shorted yet, I doubt it because the supply was still functioning to the computer, but I'll ohm it out. Edited November 1, 2023 by GDMike 1 Quote Link to comment Share on other sites More sharing options...
+arcadeshopper Posted November 1, 2023 Share Posted November 1, 2023 I'll note that most of the time you can just clip off the rifa and it will still work 1 1 Quote Link to comment Share on other sites More sharing options...
Stuart Posted November 1, 2023 Share Posted November 1, 2023 18 hours ago, GDMike said: I took a photo of T2(transformer ),I'm not sure what that does or if it's any good it looks like it's been cooked T2 ... is it just where it has been dipped in varnish to increase the isolation during manufacture? 1 Quote Link to comment Share on other sites More sharing options...
GDMike Posted November 2, 2023 Share Posted November 2, 2023 6 hours ago, Stuart said: T2 ... is it just where it has been dipped in varnish to increase the isolation during manufacture? After reviewing some o scopes online I saw these transformers and they look the same as this one. Plus the fact that I think if it was shot I wouldn't have a power supply working at all which this one does work. So I think it is just normal coloring. 1 Quote Link to comment Share on other sites More sharing options...
GDMike Posted November 2, 2023 Share Posted November 2, 2023 (edited) Here's a blown capacitor for an oilfield reactor. It blew away the bushings. Lots of paper in that one. This was found 20 ft away from where it was mounted and it fell exactly where it was supposed to, in that oil capture area of gravel. Edited November 2, 2023 by GDMike 1 1 Quote Link to comment Share on other sites More sharing options...
willbilly Posted November 15, 2023 Share Posted November 15, 2023 On 9/9/2022 at 10:07 AM, wbart84 said: I purchased it from the brother of the engineer that is currently in an assisted living facility and has no cognitive functions left. Was his first name Larry? What a shame. I have two of these guys, plus the laptop version (the TI Pro-Lite). I haven't done anything with them, but they're on the list of projects. 1 Quote Link to comment Share on other sites More sharing options...
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