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Internal Shots of the Logitech Z313

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    #21
    Re: Internal Shots of the Logitech Z313

    Here ya go.

    My only gripe is that the spkr coupling caps should be bigger. 2200u for the 4 ohm speakers usually plugged into these amps. Wanna get the -3dB point nice n low.

    That card came out of a 233MMX clone that I junked. It was upgraded from one of the many 486 clones from the glory days. It didn't belong to me- belongs to the same people the LCS1020's do. That stuff's been here since September, as well as a system I built for them...

    When I dug out my XT back in '05, I put an SB card in it. I figured if I stay within the limits of the 8-bit ISA slots, that 16-bit card could 'hang over.' Got the OPL2/3 to work with some old DOS demos and could also play 8-bit WAVs. Also found a prog to remap/convert MIDIs for custom Adlib banks and played 'em. I'd convert, check, and play them on an 'emulated' XT in DOSbox, then put 'em on a floppy and play them on the real XT.

    LOUDSP30 also ran on that XT, as did 'DOSSHELL.' Fun for a week, then the MFM hdd finally died.

    -Paul
    Attached Files
    "pokemon go... to hell!"

    EOL it...
    Originally posted by shango066
    All style and no substance.
    Originally posted by smashstuff30
    guilty,guilty,guilty,guilty!
    guilty of being cheap-made!

    Comment


      #22
      Re: Internal Shots of the Logitech Z313

      Originally posted by Th3_uN1Qu3 View Post
      btw, do you remember soundcards with onboard amps?
      i sure do, cause i still have a bunch of them

      Soundblaster 16 (CT1690 ; 1993 ; PnP version) -> ST TEA2025B (2x 2.3W)
      Soundblaster 16 MultiCD (CT2230 ; 1994) -> ST TEA2025B (2x 2.3W)
      Soundblaster Vibra 16C Prelude (CT2960 ; 1995) -> ST TEA2025B (2x 2.3W)

      and this is where it starts to get interesting..

      Soundblaster Vibra 16 (CT4180 ; 1997) -> Philips TDA1517A (2x 4W)
      Soundblaster AWE64 (CT4500 ; 1997) -> Philips TDA1517P (2x 6W)

      all the SB16's and the AWE64 had Bass/Treble adjustments via software. the Vibras and all PCI "soundblasters" (being cost-effective (read: cheap stripped down POS) cards) had no special features whatsoever.. including bass/treble settings.
      this includes all PCI "Soundblasters" based on the Ensoniq ES137x chips. those were the "modern vibra cheapos" if you wanna call them that. everything on those is done in software. they still sound better than most onboard crap though (no background noises like hissing or "computer thinking" interference caused by CPU or HDD activity)

      i remember killing a pair of cheapo speakers (with a tiny amp in them) by turning up the volume of the soundcard instead of the speakers.
      they didn't like what was coming from my AWE64 with bass and treble set to max.

      after that, i used 2 pretty good sounding small shelf speakers (each rated for 10W continuous, 14W max. IIRC) directly hooked up to the AWE64..
      card is still alive and working perfectly fine..

      Comment


        #23
        Re: Internal Shots of the Logitech Z313

        Originally posted by Th3_uN1Qu3 View Post
        They weren't ASOUND in here, but i do remember the white boxes.
        Does Encore sound right?
        I think they were just generic crap that came under different names. I still have a pair of them on the computer at my grandma's house. They sound like shit. No response whatsoever under 120 Hz. Turn up the volume and the LED light on them begins to dim with the beats. I only use them when I have to.

        Originally posted by Th3_uN1Qu3 View Post
        (btw, do you remember soundcards with onboard amps?)
        No, but now that you mentioned it, I checked an old Pentium motherboard from a Compaq and it had a TDA1517 amp, coupled with 2x 1000uF 10v caps, a 2200uF 16v storage cap, and some ESS AudioDrive chip. I wonder how it would sounds with my headphones. Probably much better and much louder than most modern onboard audio stuff.
        Last edited by momaka; 02-23-2011, 11:35 PM.

        Comment


          #24
          Re: Internal Shots of the Logitech Z313

          Originally posted by kaboom View Post
          My only gripe is that the spkr coupling caps should be bigger.
          It wasn't just a cost cutting measure. The coupling caps were intentionally downsized to direct more power to the frequencies the speakers could reproduce. 2.5W/ch isn't a lot when you're trying to deliver 30Hz.

          Originally posted by Scenic View Post
          i sure do, cause i still have a bunch of them
          I still have a SB16 and AWE64 too. The AWE64 sat in my dual-PIII till not too long ago. Unfortunately the fancy dual 370 motherboard that i bought (to be able to finally run the 1400MHz Tualatins at their rated speed and more) does not have an ISA slot anymore so i had to resort to an Audigy SE. Now i need to build an amp for my satellites as i used to run them off the AWE64 speaker output. And yeah the tone controls rocked... with the treble set to max those small bookshelf type speakers kept up with a 12" sub powered by a 75W amp.

          Originally posted by momaka View Post
          No, but now that you mentioned it, I checked an old Pentium motherboard from a Compaq and it had a TDA1517 amp, coupled with 2x 1000uF 10v caps, a 2200uF 16v storage cap, and some ESS AudioDrive chip. I wonder how it would sounds with my headphones. Probably much better and much louder than most modern onboard audio stuff.
          AudioDrive... meh. Never liked how they sounded. They were hella loud though. If your headphones aren't up to snuff, plugging them in the speaker output may damage them.
          Originally posted by PeteS in CA
          Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
          A working TV? How boring!

          Comment


            #25
            Re: Internal Shots of the Logitech Z313

            Originally posted by Th3_uN1Qu3 View Post
            And yeah the tone controls rocked... with the treble set to max those small bookshelf type speakers kept up with a 12" sub powered by a 75W amp.
            treble @ max on a sub..?
            more like bass

            Comment


              #26
              Re: Internal Shots of the Logitech Z313

              I have a SoundBlaster 128 PCI with integrated amp.

              So that means that I can connect passive speakers directly to the card??
              Attached Files

              Comment


                #27
                Re: Internal Shots of the Logitech Z313

                if you set the jumpers right (speaker output), yes.
                TDA1517P has a max. output of 2x 6W (depends on the supply voltage)

                edit: btw.. those SB128's belong to the Ensoniq ES137x series cards. Creative bought Ensoniq and started labelling them as creative. they don't support any Soundblaster features though (including the bass/treble adjustments in the windows mixer)
                Last edited by Scenic; 02-24-2011, 07:55 AM.

                Comment


                  #28
                  Re: Internal Shots of the Logitech Z313

                  They were very popular here back at that time. Nearly every computer I saw had a soundblaster PCI 128 card. They were quite affordable too.

                  Here is one without an amp
                  Attached Files

                  Comment


                    #29
                    Re: Internal Shots of the Logitech Z313

                    Originally posted by Scenic View Post
                    treble @ max on a sub..?
                    You misread it. Sub was running off its own amp, sats were running off the AWE64's onboard amp. With the treble cranked the sats were loud enough to keep up with the sub.
                    Originally posted by PeteS in CA
                    Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                    A working TV? How boring!

                    Comment


                      #30
                      Re: Internal Shots of the Logitech Z313

                      Originally posted by Th3_uN1Qu3 View Post
                      It wasn't just a cost cutting measure. The coupling caps were intentionally downsized to direct more power to the frequencies the speakers could reproduce.
                      Then what about people who liked to hook big speakers to the soundcard amp, just for fun? Like me...

                      My dad's first 'puter had an Epox Super 7 mb with a K6-2 @ 400MHz, the first release of '98, 192MB of PC-100 SDRAM, and an ISA AWE32.

                      After using headphones on the amp's output, I brought the level back up so I could use the powered speakers. Forgot to unplug the deadphones!
                      "pokemon go... to hell!"

                      EOL it...
                      Originally posted by shango066
                      All style and no substance.
                      Originally posted by smashstuff30
                      guilty,guilty,guilty,guilty!
                      guilty of being cheap-made!

                      Comment


                        #31
                        Re: Internal Shots of the Logitech Z313

                        Originally posted by kaboom View Post
                        Then what about people who liked to hook big speakers to the soundcard amp, just for fun? Like me...
                        470uF at 8 ohms yields a -3dB point of 41Hz. Even big speakers need a lot more power than the 2.5W typically provided by the soundcard to reach under that so it was quite useless to install bigger coupling caps. At 4 ohms it goes up to 72Hz though, which isn't that good anymore.
                        Originally posted by PeteS in CA
                        Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                        A working TV? How boring!

                        Comment


                          #32
                          Re: Internal Shots of the Logitech Z313

                          I need some help fixing mine and you guys are experts. My sound is very distorted, the sub doesn't seem to be producing any sound. The satellite speakers aren't very loud and produce a hum that gets louder as i turn the sound up. At max I can barely make out voices and the hum is louder than the voices.

                          What should I be looking at, the pre amps, or the heat sunk audio amps ?

                          Comment


                            #33
                            Re: Internal Shots of the Logitech Z313

                            Hum either indicates bad caps (not that likely in your situation) or something that's eating up all the power and keeping the caps empty so that ripple gets thru. You say the subwoofer is not working. I think that the subwoofer power amp (one of the chips on the heatsink) is shorted. Get a datasheet for the IC and with the speakers unplugged from the mains and your multimeter on 200 ohms scale measure between its power inputs, between each of them and ground, and between each of them and output. You shouldn't get anything, the meter should stay at "over". If any of those measurements return a low value the IC is shorted.

                            If the output got stuck to one of the rails the bass speaker is most likely toast as well.
                            Originally posted by PeteS in CA
                            Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                            A working TV? How boring!

                            Comment


                              #34
                              Re: Internal Shots of the Logitech Z313

                              Originally posted by vo_danh View Post
                              I need some help fixing mine and you guys are experts. My sound is very distorted, the sub doesn't seem to be producing any sound. The satellite speakers aren't very loud and produce a hum that gets louder as i turn the sound up. At max I can barely make out voices and the hum is louder than the voices.

                              What should I be looking at, the pre amps, or the heat sunk audio amps ?
                              Do you have the Z313s? I screwed up my board midway through "fixing it up", so it's been in my shop for a month or two now. I can help you out if you need part references...or anything else.

                              Honestly. They cost like $35. Might as well just get new ones because if you try getting parts shipped in, it's probably not going to be too cheap. The power-amp chips are totally obsolete. I'm not home right now, but I've never heard of them before when I first saw them. They're old stock.

                              Comment


                                #35
                                Re: Internal Shots of the Logitech Z313

                                I got them for <$30 they were broken and they sent me another set. I didn't have to return the broken ones so I wanted to fix them up just as a learning experience, and maybe get an extra set for another computer if i can fix it. I couldn't find any info on the pre amps with the numbers on them. I will test the power amps as soon as I get my multimeter back ( i just moved ). Thanks, any info would be appreciated, data sheets etc.

                                Comment


                                  #36
                                  Re: Internal Shots of the Logitech Z313

                                  The preamps are Youwang UTC4558.

                                  The power amps are NXP (Phillips) TFA9842J.

                                  Datasheets are attached. The underside of the board is really cheap quality. Pain in the butt to work with. I'd hardly bother.
                                  Attached Files

                                  Comment


                                    #37
                                    Re: Internal Shots of the Logitech Z313

                                    Where's the volume control in these? Is it between the line inputs and the dual opamps or between the opamps and power amp ICs?

                                    Vo_dan, increasing-hum-as-volume's-increased suggests that the volume pot is in fact between the opamps and power amps. Sounds like (haha) the power IC for the sub has shorted, pulling the supply voltage down and causing extreme ripple. This gets into the opamps via their supply leads and appears at the preamp output. That would explain the hum increasing as the volume control's advanced.

                                    If you even want to bother, perhaps to satisfy your curiosity, desolder the IC for the sub. I'll bet the sats play fine now and your supply voltages are back up again. The IC for the sub is connected in BTL, think of it as both channels of the IC being bridged. The IC for the sats has one channel per speaker, coupled with coupling caps. There is just one positive power supply.

                                    Too bad they used those old TFAs, but Mouser has some remaining stock...

                                    The TDA7370 'stereo/bridge' amp is, or was, popular in 2.1 computer speakers. So-called Altec-Lansing ones, to be specific. The schematics should make clear how the circuit is configured. Those inputs typically have an impedance between 15 and 20K. ST made a boo-boo with the coupling cap calcs!

                                    -Paul
                                    Attached Files
                                    "pokemon go... to hell!"

                                    EOL it...
                                    Originally posted by shango066
                                    All style and no substance.
                                    Originally posted by smashstuff30
                                    guilty,guilty,guilty,guilty!
                                    guilty of being cheap-made!

                                    Comment


                                      #38
                                      Re: Internal Shots of the Logitech Z313

                                      Originally posted by kaboom View Post
                                      Where's the volume control in these? Is it between the line inputs and the dual opamps or between the opamps and power amp ICs?

                                      Vo_dan, increasing-hum-as-volume's-increased suggests that the volume pot is in fact between the opamps and power amps. Sounds like (haha) the power IC for the sub has shorted, pulling the supply voltage down and causing extreme ripple. This gets into the opamps via their supply leads and appears at the preamp output. That would explain the hum increasing as the volume control's advanced.

                                      If you even want to bother, perhaps to satisfy your curiosity, desolder the IC for the sub. I'll bet the sats play fine now and your supply voltages are back up again. The IC for the sub is connected in BTL, think of it as both channels of the IC being bridged. The IC for the sats has one channel per speaker, coupled with coupling caps. There is just one positive power supply.

                                      Too bad they used those old TFAs, but Mouser has some remaining stock...

                                      The TDA7370 'stereo/bridge' amp is, or was, popular in 2.1 computer speakers. So-called Altec-Lansing ones, to be specific. The schematics should make clear how the circuit is configured. Those inputs typically have an impedance between 15 and 20K. ST made a boo-boo with the coupling cap calcs!

                                      -Paul
                                      I'll have to give it a look...Gotta trace back from the stupid pod thing, and I don't even know what wire was attached to the pot. I'll do my best.

                                      Comment


                                        #39
                                        Re: Internal Shots of the Logitech Z313

                                        I would just pull the sub amp IC and try it. Where the pots are in the ckt doesn't matter as far as the fault is concerned; it just changes the behavior. If it's between pre and power, the hum level is variable with the pot, if not, it's not...

                                        Don't waste time on that

                                        The 5401s are good for 3A, but each pair (half of the bridge) conducts for half the time. Yes, that's 'cheating,' but should still be close. They're not gonna blow up if there's 3.001A thru them either- "average rectified forward current." Most of the current flows in a large pulse each half cycle, when the instantaneous transformer voltage exceeds that of the 4700u cap. This could be 5-8A, depending on the transformer and ckt impedances. All normal with a capacitor input supply.

                                        There was a set of "unloved" computer speakers I repaired. Similar to yours, weak distorted audio masked by hum in the sats and nothing from the sub. Heatsink got hot quickly near sub IC. B+ was about 3 volts. The opamps had their own supply, so that's why anything even got through them. First thing I did was remove the sub amp. Presto! All five sats came up and supply was ~20V with negligible ripple. The driver for the sub was okay- looks like both halves of its bridge amp decided to short the supply. A new ST power IC, along with moving the polyfill away from the board, fixed it.

                                        I'll bet you one set of speakers it's the sub IC

                                        -Paul
                                        "pokemon go... to hell!"

                                        EOL it...
                                        Originally posted by shango066
                                        All style and no substance.
                                        Originally posted by smashstuff30
                                        guilty,guilty,guilty,guilty!
                                        guilty of being cheap-made!

                                        Comment


                                          #40
                                          Re: Internal Shots of the Logitech Z313

                                          I came here looking to find info on the Z313 as my daughter has a set from which some of the magic black smoke had escaped. I don't have the necessary skills to rework a switchmode power supply, so my plan was to replace it with an external. Having used the info here to find out what amps are in the box, I checked the specs online and this confirmed a guestimate someone on uk.d-i-y had made that 12V at an amp should be fine. I have now hooked this up (though I haven't had time to put any music through it yet) and it has restored a healthy glow to the "On" LED !:*^>)) Hopefully that's the job done.

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