Jump to content

techknight

68040
  • Content Count

    8026
  • Joined

  • Last visited

Posts posted by techknight

  1. On 6/20/2021 at 2:18 PM, portableleo said:

    After some reading on the forums it looks like TechKnight got much further than me. 

    Too bad the project seems to be on hold... maybe time to revisit it if there is enough interest? 

     

    Yeah, but not far enough. This just takes more power than the feeble old portable can give. I think you would be far better off with an FPGA-based project, or use one of those Amiga soft-core type CPUs like the raspberry pi which emulates a 68K. 

  2. 1 hour ago, davidg5678 said:

    I bought a cheap 10L Ultrasonic cleaner a few months ago to clean up some of my Macintosh logic boards. I had a small problem fitting a Mac SE/30 board inside the tank, but I just had to remove the metal basket that the machine came with in order to get it to fit properly. When I first started using the machine, I thought that everyone who claimed distilled water was necessary was crazy, but my home's hard well water left all kinds of nasty mineral deposits over a dead board, so distilled water is a definitely a must. After switching to distilled water, at first, I thought my cleaner was defective, as almost no dirt was being removed with each cleaning cycle. I had the stupid idea to add dish soap and isopropyl alcohol to the water and see what happened --this left horrible crusty deposits all over the board, and is an all around bad idea. Apparently, putting isopropyl alcohol into the tank can be a potential fire hazard, so I really shouldn't have done this at all.

     

    I am now using a special chemical called Branson EC in my ultrasonic cleaner. This stuff seems to be kind of hard to purchase, so I had to buy it from eBay of all places, as the typical suspects (Amazon, Digikey, Mouser) didn't have any stock available. When I add some of the chemical to distilled water and run the ultrasonic cleaner, leftover flux and dirt just float off of the PCB. Everything comes out pretty clean. After a rinse in the ultrasonic cleaner, I place the PCB in a small plastic bin, which I fill with the contents of one 8oz bottle of isopropyl alcohol. I then slosh the alcohol over the PCB to displace any water. Afterwards, I blast the alcohol off of the board with compressed air, and I let it dry overnight on some paper towels (or when I'm feeling impatient, I just dry the alcohol off using a paper towel :)).

     

    My assessment of the machine so far is that it does a pretty good job of cleaning parts of circuit boards that would be too difficult to reach by hand. When I inspect PCBs under a microscope, they normally are covered in all kinds of debris that you can't really see with the naked eye. After a cycle through the ultrasonic cleaner, the dirt is largely gone. I like how the machine can remove dried flux that is stuck underneath the legs of SMD chips --this is really sometimes really hard to accomplish with a toothbrush or q-tip because of the tiny size of the component legs and the massive bristles. I was most impressed by how well the machine cleaned a dead iPad logic board that I had coated in tons of nasty flux a few years ago. Because of the fine pitch of components on the iPad PCB, I had no real way to remove dirt, as even a toothbrush bristle would be too thick to fit in the gaps between ICs.

     

    It took me a few weeks to figure out that the ultrasonic cleaner is not a magic cleaning machine. Whether or not the ultrasonic cleaner will be useful really depends on the specific job I'm trying to do, and sometimes I can achieve better or equal results with a scrub brush in my utility sink. I'm still learning how to use the ultrasonic cleaner, so I am by no means an expert, but it definitely is a useful tool when I need it.

     

    Edit: I forgot to add that it is probably a good idea to wear some ear plugs when the ultrasonic cleaner is turned on. I've never really seen anyone else mention this, but the machine is really loud, so I started wearing ear protection to block out the noise. I don't know if this thing could cause hearing loss, but at minimum, I will say that earmuffs make it less annoying to be nearby.

     

     

    Same process i use, except... bake dry with a disposable toaster oven. Works wonders. 

  3. 29 minutes ago, PowerMac_G4 said:

     

    I started on CS 1.6 then moved on to CS:Source. The current version, CS:Global Offensive has been around for almost a decade now but has evolved a whole lot along the way. It still includes some maps from the early games though. It is an immensely fun game with a horrible, horrible community. Online games with good communities are a rare thing indeed – it tends to be the small ones that really shine. 

     

    I can't see things getting as toxic in vintage Mac world as they are in the land of online video games because the barrier of entry is so much higher but it is sad to see a slight decline starting to creep in. It's undeniable that the popularity of the hobby has skyrocketed over the last few years, hence the rather high prices of old Apple gear right now. It figures that unsavoury types would see it as an opportunity to make a quick buck.

     

    On the bright side: everyone on 68kmla seems lovely and I've never had a negative interaction here. We all just really like Macs, be they our own or other people's.

     

    My Go-To in those days were Metal of Honor Allied Assault, and Spearhead. i was on that game alot as a teenager, clans, matches etc.... 

     

    Super popular until CoD came along, and then Gamespy died out taking the server list with it. Someone patched the game, but its all european servers now. so high pings over here. 

  4. 35 minutes ago, PowerMac_G4 said:

     

    The community got bigger. Ask anyone who's played an online video game that started small then ballooned into a phenomenon. The more people there are, the more unpleasantness there is. I basically can't play a game of Counter Strike any more without being verbally abused. I'm not saying we should just "deal with it" but we do have to prepare for things to only get messier. 

     

    Thats a game i havent heard of in a long time. I havent played CS since about 2005 or so. 

  5. 12 minutes ago, ktkm said:

    I haven’t even begun to suspect the caps yet. My drive came very clean and smelled nice. But yesterday, I think I managed to kill the DC motor controlling the disk spinning mechanism after I started to fiddle with the lens trimpot for a better audio read. Now I need to find a replacement part, whatever that could be? Sigh. It bummed me out since I temporarily managed to salvage the original gear with some drilling and glue.

     

    Messing with the laser trim pot didnt kill the motor. It killed the laser. Youll need a new optical pickup. Been there done that many times. I dont mess with the laser adjustment anymore, I go after everything else first. 

     

    Leaking caps will mess with the servo and its ability to read information. I had to redo both this drive, AND a caddy load drive. the Caddy drive was much worse. 

  6. 2 hours ago, Kai Robinson said:

    I had quite enough of this kinda BS from the Amiga community - really didn't expect it here. If someone has a problem, come to me! Comment on the thread, let your problem be known and it'll be investigated and fixed. I've not shipped a board to this person either unless they're hiding behind a differrent name, so it's not like they have 1st hand experience of this. Of course i don't expect an actual reply from cowards like this who like to lurk on facebook and fling sh*t, but it'd be an interesting interaction if they did. 

     

    It used to not be here.... Not entirely sure what happened to start seeing that kind of behavior over in this community. But, people suck so it is what it is sometimes. 

  7. its hard to keep these little 9" trinitrons converged. and its a pain in the ass to do it. you also need plastic adjustment tools. 

     

    First thing is to adjust the H-STAT on the rear of the CRT Neck PCB, it will change the horizontal static convergence to bring it inline. Then, the corners have to be adjusted via the slugs that are on the yoke. You must do this with a crosshatch style pattern/image up on the screen, and use plastic adjustment tools. 

  8. Check the fuse next to the molex. Also check for breaks in and around the vias/traces near the lower left corner of the board. Because with your pictures, I am seeing issues in that area. the U1M/RP201 area. C26 will cause all kinds of strange issues if any of the traces/vias are broken to and from that capacitor. 

     

    if the op-amp is reporting the wrong information to the PMGR ADC your gonna get problems. 

  9. On 6/5/2021 at 12:54 AM, at0z said:

    Recap done, waiting on battery and hard drive cable to connect SCSI2HD. The 40SC is shot by the sounds and gunky edges, I don’t see any successful resurrection of these. 

    7FF52877-2F83-4970-956B-2DD62EB03DD8.jpeg

     

    I fixed a gunked up conner. Key is to do it BEFORE you spin it up and destroy the platter/heads. 

  10. On 6/5/2021 at 12:48 AM, eraser said:

    I've had a bit of a revelation.  Since I am not an EE maybe @techknight can sanity check?

     

    @maceffects are you certain it's the flyback transformer?  Here is what I realized (I'll try to be as concise as possible):

     

    1. Years ago I was really busy and made the mistake of sending some of my old Mac hardware off to someone (shall remain nameless) to recap and one of those boards happened to be my Mac TV analog board.  It had gone from working properly when I shipped it off to having video that looked just like what @Garrett_B posted when it returned.  I was furious and depressed and put it on a shelf until I had more time to diagnose it.

     

    2. During my pandemic isolation I started doing my own recapping, and in the process was able to get multiple systems with this same exact Sony Trinitron tube (including Apple AV14 monitor, Mac TV, and an LC575) working with crisp and stable video.  In the process I noticed that all of these Apple designs use a very similar main analog board and even the component labels match.  They also share another very interesting similarity ...

     

    3.  A few days ago I noticed that @maceffects had posted a list of caps for the Mac TV analog board but there was, what I thought, a huge missing piece of data: the type of capacitor.  Then it hit me.  The nameless individual I referenced above [1] had used low-quality general purpose (GP) caps for everything on the logic board.  But in my work with all of these analog boards I've been soldering on Apple specifically used low impedance (LI) caps for a number of the ones in the CRT circuit.  Consistently from board to board specific ones, even through changes in vendor (Nichicon, UCC, Rubycon), all of these specific caps were LI designs.  One of those LI caps in particular, CF8, is known to cause unstable video and distortion when it drifts off spec due to leakage or other issue.  Replacing it with a correct one restores proper video.  

     

    I am not an electronics expert (I know exactly enough to be dangerous) but I do know that CRT circuits have a lot of complicated inter-related feedback mechanisms that expect the correct resistance and capacitance in a circuit in order to work properly.  Is it not reasonable to think that maybe caps of the wrong impedance value (or ESR) - either because they have failed due to age, or picking the wrong replacement cap - are causing or at least contributing to this problem?  

     

    Maybe I am totally wrong and the flybacks really are the universal cause of this problem, but my anecdotal experience with 1, 2, and 3 make me think that maybe there is a far more simple solution we are overlooking here.  At a minimum maybe the flyback transformer is responsible for fewer of the problems than we blame them for.

     

     

    Any time i recap an SMPS circuit or anything with high frequencies, i automatically order low impedence/ESR capacitors, its just habit for me. So this is something i never thought of during the event of NOT having the right caps. 

  11. that reminds me, I have one of those big Sony trinitron (B&W G3) style monitors here that someone brought to me while back. It has a bad flyback as well. it draws too much current in higher resolutions which trigger an x-ray protect shutdown. 

     

    Only getting worse. 

  12. 3 minutes ago, cheesestraws said:

     

    I've always conceptualised the flyback as a box full of analogue magic and danger in approximately equal doses...

     

    Yeah, it can be. it was even worse in the vacuum-tube type TV era. those flybacks were all specific, and they were all more intimately tuned with the horizontal output than they are "today". The horizontal output pulse only affected from center-right of the CRT. The flyback collapse/response affected center-left. Thats why this is important. 

     

    Newer/more expensive designs. (like Philips RPTVs from the late aughts) had HVGs instead of Flybacks, which they were very similar but they were a self contained unit that was self-oscillating at its own frequency and was in no-way tied to the horizontal output stage, except for phase locking. These are muuuuch easier to substitute if it ever came down to it. 

     

    But, flybacks that are tied into and intimately involved in the horizontal output network? nope. 

  13. 28 minutes ago, PowerMac_G4 said:

     

    Flyback failure is sadly only going to become more and more prevalent over the next decade. These parts were never intended to last 30-40 years. We really need to figure out how we can actually save these old machines from a currently-inevitable, permanent death. Is it possible to create an equivalent to a flyback transformer from more modern parts, for example? What's actually inside a flyback transformer besides a pair of coils? I recently expressed my frustration at just how sparse the information is on these parts and what they actually do. I'm no dummy when it comes to electronics but the flyback has always mystified me.

     

    I've tried reaching out to HR Diemen to see if they'd be willing to release/sell their old designs into the public domain but their web presence is near-zero and the forms on their decrepit site do not work. I'm not sure the company even still exists - the phone number on their site is not connected any more.

     

    What we really need is a scenario like that which has played out over in the BUG Pickles thread, where the original designer of the cards was tracked down, contacted, and has now gotten involved with trying to revive the extant cards. Finding the person or persons responsible for the engineering of these transformers would be a huge leap for the community. If schematics for these parts cannot be sourced then there is a huge amount of work to be done on reverse-engineering dozens of different models. It is sad to think that the information is out there yet so far from the right hands. 

     

    The flyback transformer is a critical component in the circuit. you cant just substitute it either. it requires intimate knowledge of the circuit design that only the engineer knows, or a damn good reverse-engineer. 

     

    Why? because the flyback not only produces a high voltage, it also produces all the secondary scan voltages for the other circuits in the set. Vertical Sweep, B+ Boost, etc.... Including focus/screen. Also, its part of a tuned-circuit with the horizontal output stage, and all the other support components are selected around that tuning. And if that weren't enough, different flyback designs have different frequency responses and losses over frequencies. 

     

    This doesn't include the x-ray protect, and high voltage regulation feedback circuitry that is connected to a tap on the flyback as well. 

     

    So its not as easy as swap-n-go. I wish it were. 

     

    @apm can certainly elaborate more on this subject too. 

  14. 6 hours ago, tt said:

    @techknight It may be the photo, but TBH I think it looks better on other types of CRTs... is it a Trinitron tube? Also the size is kind of small, most of the demand seems to be for 20"+ unless it is a premium monitor. I agree with the sentiment, it would be good to see these kept with their intended machines.

     

    These monitors I think are Mitsubishi based. they share the flyback with the LC Toppers. 

  15. Love the concept. I knew that a IIgs monitor was just an RGB monitor at heart. But..... its posts like these that create a huge run of demand on things like that. 

     

    Now if those IIgs monitors were hard to be found before, now they will be even harder to find and price will jump. haha. 

     

    Oh well. 

  16. 3 minutes ago, aladds said:

    I know that there are versions of NU which can corrupt files when paired with "incorrect" system versions (Usually old NU with a more modern system), but I always thought you had to actually *run* it for that to occur.

     

    The fact you were able to re-copy files and things issues not occur again rules out anything hardware related in my opinion.

     

    7.5.3 is also pretty buggy - could just be some issue there?

     

    Recopying them on the Q700 still caused issues. I had to move the drive and cables back over to my IIsi and LC2. Then it worked. 

     

    7.5.3 Buggy in what ways? I dont have a list. 

  17. 3 hours ago, MrFahrenheit said:

    Sounds like the kind of problem that happens when termination isn’t correct, or a bad SCSI cable. 
     

    Are you using one of those SCA80 adapters?  If so, is it one that has termination on the adapter?  I’ve had experience with a lot of these adapter boards and some don’t have enough termination for the number of lines a SCA80 drive needs to be fully terminated. 
     

    Also, back in the day there were incompatibilities between FWB HDT specific versions and specific Macs / specific OS versions. What version of System Software and FWB are you using?  Make sure the version on your drive is compatible with your OS and the Q700. 

     

    I dont recall what version of HDT it is. And yes, its a terminating adapter. I forget where I bought them, but they have a transistor or two and a bunch of resistors on the PCB. Like I said, it works fine in my LCII and my IIsi. its only the Q700 giving me beef. 

     

    System 7.5.3

×
×
  • Create New...