Soundcard disappears in DOS/Win98 \ VOGONS

Soundcard disappears in DOS/Win98

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First post, by Riikcakirds

Posted on 2022-06-02, 15:24

Riikcakirds Offline

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Joined: 2020-11-02, 18:18

Sound card is IPLAW35 CRYSTAL CX4237B-XQ3 (ISA).

After booting to DOS, the POST screen lists PCI devices and under that shows my soundcard detected as an ISA PNP DEVICE.
Then I have around 1 minute to initiate the card before it disappears and can't be detected by unisound or it's own dos driver.

I have noticed if I don't connect the 3.5mm stereo jack to lineout the card will sometimes not disappear, it will still be detected 30 minutes later but as soon as I plug in the 3.5mm jack back in to line out the card disappears from DOS. Motherboard is 440BX and has no other problems. Tried the soundcard in two other motherboards with different power supplies and it has the same issue.
Does this sound like a capacitor problem (they look in very good condition)?

Reply 1 of 2, by Riikcakirds

Posted on 2022-06-03, 13:22

Riikcakirds Offline

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Joined: 2020-11-02, 18:18

I removed the caps, they came off very easy on this card and tested them with an ESR Meter. According to the chart they are what you would expect. The capacitor tester I used showed they are all within 98% of their rating.
I soldered on new capacitors and the behavior of the card is exactly the same, so I'm a bit lost with this one.

Rarely the card is found at boot and will work for hours (with 3.5mm lead in line out). Usually it disappears from DOS after 1 minute, or I remove the 3.5mm stereo lead, boot and card is found, then plugging the 3.5mm lead to line out causes the card to disappear.