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About justacruzr2

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    Space Invader
  • Birthday 09/20/1954

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    Chicago, IL
  1. Same here. Currently working on a vintage cassette deck. Anyway, the CC9900 I was talking about was the Rev A model. I also have the first model and rebuilt it also but I haven't adjusted the trim pots yet. Still have the readings you took on yours before you disassembled your card so I have the specs to do that when I get around to it. Was more interested in getting the Rev A card working first so I could start repairing the floppy drives. Need a working card first before I can determine whether repairs to the floppies were successful. Keep at it....you'll get it done.
  2. Sounds like your repair list overfloweth. Good luck with all of it. All the general purpose ICs and transistors I got from DigiKey. Some of the caps and resistors I had on hand. The rest I got from various sellers on eBay. There wasn't one source for everything and it probably cost me close to $100 to rebuild the card. Not cheap but what's the alternative? A good CC9900 on eBay, when one comes up, sells for much more than that. No real good solution I'm afraid.
  3. I can add a little about the details of what I did and what I found. I replaced all the chips on the card except the ROMs and the PALs. They were OK. I replaced the 9901 although I'm sure it was OK as I had tested it with another known good 9901. I know the 7406 was bad and maybe the one next to it (can't remember it's number...maybe 7438). I also found several caps that were bad. They had dark brown spots on them that suggested they overheated and weren't noticeable until I looked at them with a magnifier. I replaced all the caps just to be sure. Also all the resistors, diodes and transistors. I didn't replace the crystal or the LED. That's about it...hope that helps.
  4. Not sure if you're talking about the disk controller card or the floppy drive so I'm going to assume you mean the disk controller card which we discussed months ago. All I did was just rebuild the card since I don't have any technical equipment, other than an ohm meter, to track problems down. I thought that was what you were doing too with your CC9900.
  5. A BIG thanks to all of you. And it's great to see 100% concensus. @ Stuart Thanks for answering what was to be my next question. I do understand how to translate the markings to the value but was not sure if it was expressed as micro farads (uf) or pico farads (pf). Thanks for clearing that up. @ Ksarul Definitely is my intention and the ones in this photo too (even though they don't look bad) which DigiKey identified as polyester film caps. DigiKey was unsure about the ones that all of you identified. Probably because as CC Clarke says they have been largely eliminated so they don't see them anymore. These drives are 31 years old and need some freshening up as long as I'm working on them. Actually I'm working on 2 drives. They both took a spike from a static discharge along with the disk controller. The controller I already repaired and tested with a known good drive and it's OK (the CC9900 we were talking about months ago). @ CC Clarke Thanks and if I can't get polystyrene from DigiKey I'll go with the polyester (mylar) as you suggest.
  6. Can any of you electronics experts out there identify what type of capacitor is shown in this photo. This is the main board in the floppy drive I'm repairing and I would like to replace it with the correct type. I know it's not ceramic disc, electrolytic or tantalum. I believe it's some kind of film type....but which? And it's clear to see that the cap in the lower right corner is blown. The others may be compromised as well. Thanks for any help you can provide.
  7. A cheaper alternative than the MG eproms is to simply press the space bar twice. This will land you at the TI menu. This was a known workaround for the software that would not work correctly from the CorComp menu. Try this first before you spend money. I can not be sure that this method works for everything but it does work for everything I have.
  8. Sorry to hear that. I purchased many different things from him over the years (back in the day) and he was one of my trusted sellers. He always dealt fairly and honestly.
  9. Another good addition to the collection of documentation would be the "Hardware Manual for the Texas Instruments 99/4A Home Computer" written by Michael Bunyard and released in 1986. It is generally referred to as the Bunyard Manual. Michael Bunyard was a Senior Member of the Technical Staff at Texas Instruments for 16 years. The manual is a technical manual and covers all the hardware TI released for the the 4A including the console. It also includes console schematics. There was also a "SAMS Computerfacts" Technical Service Data for the 4A which includes schematics and service diagnosis procedures.
  10. Thought I'd add this for what it's worth. If you like the feel of DOS there was a DOS system released for the 4A called Command DOS. It was written by Monty Schmitt and released by Ryte Data. I have this and it works well and is a fun way to interact with the 4A
  11. Fujitsu M2551A drives. These are the early models (bought from Triton) that don't have any additional numbers after the model number. Later ones have an "08" or "26B" after the model number and the main board is slightly revised and not compatible with the earlier model.
  12. Actually it's 2 drives. They took a hit when the FDC crashed and took one of my floppies with it. The drive lights come on, the disks spin, but they don't read/write.
  13. Anyone know of someone or someplace that does floppy disk drive repair (reputable of course)? It's a bit more complicated than FDC repair and I'm not having any luck doing it myself.
  14. This will make you cry. I bought an extra PEB (and some other things which included the European version of the Starter Pack 1&2 and the Game Writers Pack !&2. Not sure but I think these were only released in UK) when Triton was going out of business. They were selling the PEB, brand new in sealed box, for $50.
  15. Got it.... Got it...Thanks. "The one next to the two eproms, mine did not have any jumpers, but in other photos, in my archives, I see jumpers in several configurations, is this why my TI kept coming up with a cyan screen, was this tear down preventable?" I've seen the same thing in another photo. But mine has only 1 jumper between pins 2 and 3 on the lower 3 pin jumper pack. Those other jumpers in other photos may be for testing purposes. I don't know for sure. All I can say is that my card works except that it doesn't recognize a disk in the drive. I doubt that's the reason why. There are still some minor unresolved issues like setting my trim pots and until I have addressed all those things I'm not pointing the finger at the jumpers. "The area where the trim pot is marked, what is the value on your pot, mine keeps fluctuating around?" Haven't done mine yet. You do have to do the procedure correctly to be able to adjust it correctly. The master Reset has to be pulsed first before you jumper the pins and put it into test mode. The better and correct procedure is in the datasheet for the WD2793. I downloaded it and read it and it's very thorough. The setting that other fellow who built his own disk controller card is incorrect for 5 1/4" floppies. He said to set the 50K pot to 250ns but he didn't mention that setting is for 8" floppies. The datasheet says 400ns for 5 1/4's. I recommend you download that datasheet and read it. The procedure for setting both the 50K and 10K are there. Afterwards they should settle down and give a steady reading. "And what is the purpose of the two caps on the marked regulator, for decoupling or smoothing out of the by-passed voltage?" Basically you are correct. The answer is actually in this thread a page or 2 back. Hope that helps!
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