The ghetto mod thread

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  • stj
    Great Sage 齊天大聖
    • Dec 2009
    • 30901
    • Albion

    #261
    Re: The ghetto mod thread

    i have seen rubber used.

    problem is, even rubber will harden & crack eventually.

    Comment

    • SteveNielsen
      Retired Tech
      • Jun 2012
      • 2327
      • USA

      #262
      Re: The ghetto mod thread

      Yes but certainly not as quickly as the foam does. Foam also has more acoustic transparency than solid rubber and in my mind foam would seem to allow a certain amount of back-cone radiated sonic energy to mix with front radiated sound out of phase.

      Comment

      • momaka
        master hoarder
        • May 2008
        • 12160
        • Bulgaria

        #263
        Re: The ghetto mod thread

        Originally posted by SteveNielsen
        I wonder if someone could come up with a different material to use for the cone edge surround besides the crappy foam, say a thin solid rubber surround like a bicycle inner tube is? I think the paper surround is promising.
        Hi-end car woofers usually come with rubber surrounds (or rubber-like, at least). IIRC, the rubber doesn't provide acoustic damping as good as foam. However, it is a bit tougher, so it allows more power to be pushed in the speaker (which, if you've seen videos of car woofers flexing hard and playing loud, you will understand why - foam would likely rip apart at those power levels).
        See this one, for example:
        https://www.youtube.com/watch?v=XrVSj0WwtMM

        And here is someone's home-brew version :
        https://www.youtube.com/watch?v=C2k3jE4kqKE

        Other material I have seen used somewhat often is rubber-impregnated cloth. But I'm not sure how good of a material that is for high-power speakers - especially woofers.

        The ones I saw with cloth surrounds were a little "soft" - i.e. it was easy to move the speaker cone. Ironically, with both of these instances, the speaker enclosure was a ported design. From what I've been reading, soft surrounds are better fit for sealed enclosures, since ported and transmission line (T-line) enclosures don't provide any means to limit the cone movement below their tuned frequency, which means the speaker can easily bottom-out and possibly get damaged.

        Anyways, the Cewin Vega speaker above, along with my other CV drivers all have datecode stamps from early to mid 90's and all are with completely rotten foam surrounds. I think oldest one is a '92 or '94, and youngest is '96 or '97. So more or less, that foam has lasted probably about 15 years (I'm not counting the last few, because the foam probably started to rot badly then). This isn't too bad overall, IMO.

        Still, I think rubber is better. The Sony SS-MB215 floor standing speakers I use in my room as monitors use rubber surrounds on the woofers. My family got these speakers back in 2002 or so from Sears (so they are close to 14 years old now). The rubber is still good on them today with no signs of hardening anywhere.

        Originally posted by SteveNielsen
        Did you use anything like the old school speaker dope to kind of "vulcanize" the paper?
        Nope, I haven't.

        Ever since I fixed the Realistc Nova-18, however, I have been thinking about coating the paper with latex paint. I figured latex is fairly rubbery and we already have a few cans of leftover interior latex paint anyways, so might as well try it. I will most likely test it on the paper surround of the CV speaker above. Probably next week or so. Will let you know how it goes.
        Last edited by momaka; 02-08-2016, 09:41 PM.

        Comment

        • Compgeke
          Badcaps Veteran
          • Feb 2014
          • 524
          • USA

          #264
          Re: The ghetto mod thread

          Found this in a C64 with ram problems. Pin1 was cut, but still not that great of a fix.
          Attached Files

          Comment

          • stj
            Great Sage 齊天大聖
            • Dec 2009
            • 30901
            • Albion

            #265
            Re: The ghetto mod thread

            i hate that trick, it causes excess loading and wont help if an input or output is shorted on the old chip.

            Comment

            • Compgeke
              Badcaps Veteran
              • Feb 2014
              • 524
              • USA

              #266
              Re: The ghetto mod thread

              I do as well. Makes it harder to diagnose when you find something like that and you don't know if that's the cause or something else is bad and they tried that as a fix that didn't work.

              Piggybacking is only something I do for diagnostic, like stack a 2nd 4164 on top of one of the existing ones to see if that chip's bad. Very useful trick for old computers, saves a lot of time from desoldering all the chips and soldering in sockets then swapping until something works.

              Comment

              • stj
                Great Sage 齊天大聖
                • Dec 2009
                • 30901
                • Albion

                #267
                Re: The ghetto mod thread

                most dram failures cause the output to stick,
                you can spot them with a logic probe.

                that and the burned-finger test

                Comment

                • momaka
                  master hoarder
                  • May 2008
                  • 12160
                  • Bulgaria

                  #268
                  Re: The ghetto mod thread

                  Originally posted by Compgeke
                  Found this in a C64 with ram problems. Pin1 was cut, but still not that great of a fix.

                  Now that's what you call chip pr0n
                  (I guess that's where the piggyback term originates from? )

                  Comment

                  • Agent24
                    I see dead caps
                    • Oct 2007
                    • 4913
                    • New Zealand

                    #269
                    Re: The ghetto mod thread

                    Probably they did it for a quick test and it worked, so they left it like that to save time.

                    Of course if I was now trying to troubleshoot it, I'd remove both chips and replace with a socket.
                    "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                    -David VanHorn

                    Comment

                    • goontron
                      5000!
                      • Dec 2011
                      • 4108
                      • US

                      #270
                      Re: The ghetto mod thread

                      I had two dead acer aspire netbooks. I made one with the good parts. Blue one had a good everything but display and SDcard slot. The red one had a bad motherboard, no ram, no HDD. I put the red display on the blue unit and put the SDcard slot in it too. The touchpad buttons on the blue one had gouge in it, so I put the red one in its place. It's complete with a bodged in 64gb SSD and a crap looking (internally good. Protected well. LG cells!) Battery. It also has a RTL8188 N wireless in place of the atheros G wireless.
                      Attached Files
                      Last edited by goontron; 02-16-2016, 09:18 AM.
                      Things I've fixed: anything from semis to crappy Chinese $2 radios, and now an IoT Dildo....

                      "Dude, this is Wyoming, i hopped on and sent 'er. No fucking around." -- Me

                      Excuse me while i do something dangerous


                      You must have a sad, sad boring life if you hate on people harmlessly enjoying life with an animal costume.

                      Sometimes you need to break shit to fix it.... Thats why my lawnmower doesn't have a deadman switch or engine brake anymore

                      Follow the white rabbit.

                      Comment

                      • dragos2009
                        Senior Member
                        • Mar 2013
                        • 110
                        • Romania

                        #271
                        Re: The ghetto mod thread

                        by the way i really like the look of that acer goontron looks really nice like a custom job

                        Comment

                        • goontron
                          5000!
                          • Dec 2011
                          • 4108
                          • US

                          #272
                          Re: The ghetto mod thread

                          One thing i didn't notice was the display hinge end pieces are one blue and one red.

                          Unrelated links that i will need later: http://www.hddoracle.com/viewtopic.php?f=2&t=276
                          http://www.hddoracle.com/viewtopic.php?f=100&t=155
                          Last edited by goontron; 02-16-2016, 01:56 PM.
                          Things I've fixed: anything from semis to crappy Chinese $2 radios, and now an IoT Dildo....

                          "Dude, this is Wyoming, i hopped on and sent 'er. No fucking around." -- Me

                          Excuse me while i do something dangerous


                          You must have a sad, sad boring life if you hate on people harmlessly enjoying life with an animal costume.

                          Sometimes you need to break shit to fix it.... Thats why my lawnmower doesn't have a deadman switch or engine brake anymore

                          Follow the white rabbit.

                          Comment

                          • eccerr0r
                            Solder Sloth
                            • Nov 2012
                            • 8658
                            • USA

                            #273
                            Re: The ghetto mod thread

                            Originally posted by Compgeke
                            Found this in a C64 with ram problems. Pin1 was cut, but still not that great of a fix.
                            Now I'm not an expert at C64 hardware as I've never owned one, but it also could be possible it wasn't an aftermarket fix, but rather a design fix. I'd imagine if it was an aftermarket fix, pin 15 needs to be cut. But as a design fix, possibly the output of the LS257 simply didn't have enough drive strength and the quick fix was to use two (assuming the inputs aren't loaded down too much.)

                            Design fault, yes, alas, if it works, it works. I'd be worried if just pin 1 was cut as a repair... pin 15 must be cut as a repair...

                            Comment

                            • Agent24
                              I see dead caps
                              • Oct 2007
                              • 4913
                              • New Zealand

                              #274
                              Re: The ghetto mod thread

                              From the photo it looks like Pin 16 (Vcc) was cut on the old chip. Without power I don't see how you'd get extra drive current though, so I doubt that's why the new chip is there.

                              Both Pin 1 and Pin 15 are inputs. I don't see how cutting either of those would make sense. Pin 15 is for disabling the outputs, but only when pulled high. Unless you hoped it would float high (probably a bad idea).

                              But why would you set the outputs disabled on a faulty chip? Who says it would disable them anyway?
                              Last edited by Agent24; 02-17-2016, 10:29 PM.
                              "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                              -David VanHorn

                              Comment

                              • stj
                                Great Sage 齊天大聖
                                • Dec 2009
                                • 30901
                                • Albion

                                #275
                                Re: The ghetto mod thread

                                commodore dont do that, all pcb revisions are error free.
                                the only change to the 64 was to add some diodes to the serial port, and that resulted in a pcb change.

                                Comment

                                • eccerr0r
                                  Solder Sloth
                                  • Nov 2012
                                  • 8658
                                  • USA

                                  #276
                                  Re: The ghetto mod thread

                                  hmm... hard to tell if pin 16 was cut... that may do more for disabling the old chip, but it would still leak. Not sure why they simply remove the old chip. If they were cutting pins, might well just cut all of them to stubs, take off the body of the old chip, and solder the new chip to the stubs?

                                  Comment

                                  • stj
                                    Great Sage 齊天大聖
                                    • Dec 2009
                                    • 30901
                                    • Albion

                                    #277
                                    Re: The ghetto mod thread

                                    pin16 is the 5v supply.

                                    Comment

                                    • stj
                                      Great Sage 齊天大聖
                                      • Dec 2009
                                      • 30901
                                      • Albion

                                      #278
                                      Re: The ghetto mod thread

                                      Originally posted by eccerr0r
                                      If they were cutting pins, might well just cut all of them to stubs, take off the body of the old chip, and solder the new chip to the stubs?
                                      i'v seen that tried and had to clean up the mess for the owner,
                                      Atari used to recommend it!!

                                      when you try to solder to the stub it becomes loose and flops around - usually ending up stuck to the one next to it!

                                      Comment

                                      • SteveNielsen
                                        Retired Tech
                                        • Jun 2012
                                        • 2327
                                        • USA

                                        #279
                                        Re: The ghetto mod thread

                                        Originally posted by Compgeke
                                        Found this in a C64 with ram problems. Pin1 was cut, but still not that great of a fix.
                                        I've seen that on a few boards as well back in the 80s. Not limited to any particular brand as I recall, it was just done and if it worked then it was left alone. Shitty practice but it happened.

                                        Comment

                                        • eccerr0r
                                          Solder Sloth
                                          • Nov 2012
                                          • 8658
                                          • USA

                                          #280
                                          Re: The ghetto mod thread

                                          I guess once you cut off the plastic of a soldered DIP, it should be fairly easy to remove the remaining pins one by one especially if it becomes loose and flops around... Still don't get why it was stacked other than for drive strength!

                                          Comment

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