It's a little unusual for resistors to go bad. How did you determine they are faulty? Do you have any pictures of the card you could share?

keep in mind that the LAPC-I needs the -5v rail present - else you will get no sound output at all
I happen to have the lapc-i service manual, will check what R49 and R50 are and report back

just checked, both R49 and R50 are 33K resistors
first make sure you have a -5v rail

Thanks for the replies and the resistor values, pic:

Where I am checking for the -5v on the card?

-5v is ISA pin B5 (check the pinout here: https://en.wikipedia.org/wiki/Industry_Standard_Architecture )
basically the 5th pin from the right but on the back side

you should first determine if your PSU supplied -5v , if it is an AT one then it is ok but ATX ones dropped it fairly soon after their release

Thanks keropi , checked the psu and no -5v. Went hunting for some others psu's and none of them have it either.
Will need to try and source one now, I guess that will be an AT psu ?
Do any ATX have -5v ?

You could also build (or buy) yourself one of these (or any variation of such), if you don't want to go hunting:
https://www.philscomputerlab.com/voltage-blaster--5v.html

ketma wrote on 2024-06-19, 21:23:

Do any ATX have -5v ?

Older ATX power supplies from the late 90s and early 2000s should have -5V.

Yeah without -5v you won't hear anything front the lapc-i as the audio amp circuit needs it to operate. Hopefully this will be the only issue and you'll enjoy this iconic card soon! I would suggest holding off messing with the resistors until a proper PSU solution is found. Maybe they just look old, can you upload photo of them?

Thanks, I've ordered a voltage blaster as mentioned by MJay.9.9.

As you say keropi i'll try this first before messing with them. I uploaded a photo in an earlier response, did this not show ?

Many thanks for all the support.

yeah now I see , they sure look bad
you can check with multimeter if they read anything , perhaps not a bad idea to replace them before testing further

Also, consider extensive cleaning of that board with some deoxit. :$

Something nasty has gotten on that board at some point. There is oxidation/corrosion in that part of the board.

Hi, just a further update, so I cleaned the area and afterwards the resistors looked much better, I also ordered and received a Voltage Blaster and then tested the card to see if was working now it would have the -5v it requires, and to my delight it WORKS !

No popping, static, background noise - just perfect music in all the games I tested.

So pleased the card is working and in my collection - thank you for all the responses.

excellent news!!! enjoy this legendary card 😀

Nice!