VOGONS

Gateway 2000 16MVCARD

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First post, by ecliptik

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I am trying to get a Gateway 2000 16MVCARD soundcard working and am stumped on what to do next. Card is detected and configured, but sound volume is extremely faint when using Line Out and occasionally works when using Amp Out but is distorted and scratchy (sample mp3 attached). With Amp Out even when the system isn't doing anything there are sometimes pops and other odd noises from the speakers.

The system is a Gateway 2000 Slimline desktop with a 486DX2-66Mhz, 48Mib of memory, CF2IDE on IDE Master, 8x CDROM on IDE Slave, Gotek Floppy Emulator, Picogus (IRQ 7 and DMA 3 in USB mode) and powered by a PicoRC with a 80 Watt PicoPSU. I have tried running the system only with the sound card in case it was a power issue but same results.

Here's what I've tried so far.

- Read Tenormans excellent writeup
- Read other similar threads
- Installed drivers from Gateway 2000 SystemCD 3.5 for MS-DOS 6.22
- System configures card on boot using the JAZZ.SYS driver
- Sony CDROM interface works and detects a 2x CDROM with MSCDEX.EXE
- Replaced all electrolyte capacitors - Rubycon for 1000uf and 50uf, WIMA film for 1ufs and Nichicon for 47uf - verified all are soldered well and polarity is correct
- Replaced LM1877N-9 with new-old stock chip (and put a 14 pin round IC socket on the board for it)
- Ferrite beads are all intact and show continuity
- Tested all resistors in Line-Out and AMP Out path and re-flowed solder
- Push and bend test with no difference in sound output
- Measured 11.5v on Pin 14 of the LM1877N-9
- ISA card screwed securely into chassis

I'm running out of ideas, and don't really know enough electrical engineering to test the paths more. I have a basic multi-meter, soldering iron and other tools, but that's about it. I've tested with both known working speakers and headphones and same results. Any ideas?

autoexec.bat

GoTo %config%

:PG
LH C:\DOS\MSCDEX.EXE /D:MSCD000 /M:5
LH C:\WINDOWS\SMARTDRV.EXE 512 256 C A-
GOTO COMMON

:PGLITE
LH C:\DOS\MSCDEX.EXE /D:MSCD000 /M:5
GOTO COMMON

:WINPG
LH C:\DOS\MSCDEX.EXE /D:MSCD000 /M:
LH C:\WINDOWS\SMARTDRV.EXE 2048 1024 /L
GOTO COMMON

:CD
LH C:\DOS\MSCDEX.EXE /D:OPTICAL /M:5
LH C:\WINDOWS\SMARTDRV.EXE 512 256 C A-
GOTO COMMON

:CDLITE
LH C:\DOS\MSCDEX.EXE /D:OPTICAL /M:5
GOTO COMMON

:WINCD
LH C:\DOS\MSCDEX.EXE /D:OPTICAL /M:5
LH C:\WINDOWS\SMARTDRV.EXE 2048 1024 /L
GOTO COMMON

:CLEAN
ECHO Clean boot - no drivers loaded
GOTO END

:COMMON
LH C:\DRIVERS\CTMOUSE.EXE
ECHO %config% configuration loaded
GOTO END

:END

config.sys

[COMMON]
DOS=HIGH,UMB
FILES=40
BUFFERS=30
LASTDRIVE=H
DEVICE=C:\DOS\HIMEM.SYS /TESTMEM:OFF
DEVICE=C:\DOS\EMM386.EXE NOEMS I=B000-B7FF
DEVICEHIGH=C:\G2KAUDIO\JAZZ.SYS P220 I5 D1 E3 T330 Q2
STACKS=0,0

[menu]
menuitem=PG, PicoGUS with SMARTDRV
menuitem=PGLITE, PicoGUS
menuitem=WINPG, Windows with PicoGUS
menuitem=CD, Optical Drive with SMARTDRV
menuitem=CDLITE, Optical Drive
menuitem=WINCD, Windows with MSCDEX
menuitem=CLEAN, No Drivers
menudefault=PG,5

[PG]
DEVICEHIGH=C:\PICOGUS\CDMKE.SYS /P:250 /Q

[PGLITE]
DEVICEHIGH=C:\PICOGUS\CDMKE.SYS /P:250 /Q

[WINPG]
DEVICEHIGH=C:\PICOGUS\CDMKE.SYS /P:250 /Q
DEVICE=C:\WINDOWS\IFSHLP.SYS

[CD]
DEVICEHIGH=C:\DRIVERS\VIDECDD.SYS /D:OPTICAL

[CDLITE]
DEVICEHIGH=C:\DRIVERS\VIDECDD.SYS /D:OPTICAL

[WINCD]
DEVICEHIGH=C:\DRIVERS\VIDECDD.SYS /D:OPTICAL
DEVICE=C:\WINDOWS\IFSHLP.SYS

[CLEAN]
REM No drivers loaded

Reply 1 of 3, by Pickle

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have you tried different positions of those 2 jumpers?

edit: I dont see a normal supply you might be missing the negative 5 volt rail

edit #2: looks to me the card uses -5 v, its pin 5 on the b side (side with chips)

edit #3: i see the pico supply now, that on its own does not supply -5 v. I think that attached to one of those current monitor's, which i dont know supply's the -5 rail.

Reply 2 of 3, by Babasha

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-5v required

Need help? Begin with photo and model of your hardware 😉

Reply 3 of 3, by ecliptik

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Thank you for the replies. I tested the PicoPSU and 16MVCARD and both show -5v on Pin 5.

Testing the other power rails, the only concerning one is Pin 7, -9.68v, which should be -12v. Testing the PicoPSU directly it measures -9.7v from the voltage regulator. I'm not well versed in electronics to know if this is normal.

Pin 3: +4.89v
Pin 5: -5.05v
Pin 7: -9.68v
Pin 9: +11.96v
Pin 29: +4.89v

I know this a bit of an odd combination, as I'm using a PicoRC supplying power to the AT connector and directly to the ISA bus. A Creative CT2940 sound card in the same slot works without any issues, although it lacks Pin 5 completely. The PicoGUS I have also doesn't have a Pin 5 (well it does just not connected to anything).

Tracing the -5v path it goes through surface mounted capacitors, C7 and C8, and makes it's way into one of the TI LF353 Wide-Bandwidth JFET-Input Dual Operational Amplifier chip U3, Pins 4 and 8. The LF353 data sheet has Pin 4 as -VCC and Pin 8 as +VCC. There are 6 of these LF353 chips on the board. Testing Pins 4 and 8 on all 6 gave -5.01v on Pin 4 and +5.02v on Pin 8, same measurements when idle and while playing sound (Doom demo). This is within the recommended operating conditions according to the datasheet.

Since these are amplifier chips, and sometimes L is louder than R (assuming 3 ICs per channel), I wonder if one or more of the chips is bad. Doing a quick search for LF353 failure, it seems they might have some known issues. Maybe worth putting in an order for some new ones and replacing them?

Another thing I'm wondering about is if the crystal oscillator on Y1 is bad, since there's a repetitive clipping sound instead of MIDI music (I can tell it should be music since it stops/changes when music should).

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