First post, by Ozzuneoj
- Rank
- l33t
So, I got a CT1350B in its original box with a lot of vintage hardware last fall and I decided to try it out today. It was missing its volume knob (the pot was still there) though. Thankfully, I recently obtained a Media Vision Pro 3D card that needs an odd-ball 3-connector filter capacitor replaced, which is going to have to wait until I have a few other small parts to order. Since that card uses an identical volume dial and attaching screw, I borrowed them for the CT1350B so I could actually adjust the volume.
Now, the problem I have is that I get a strange scratchy hissing noise from the output. I've connected it to two different devices (a monitor with built in speakers and a DIY mini-amp I built). Both exhibit the same problem. I tried a few games that are from the late 80s to early 90s and generally all I get is that there is some kind of change in the noise when digitized sounds or OPL music should be playing, but there is no recognizable music or sound coming through the speakers.
I tested Silpheed, Zeliard and Nascar Racing (CD version). The computer is running Windows 98SE (on a 440LX board running a Pentium II 266) for the sake of testing, and I did install the card as a sound blaster compatible in Windows. What's strange is that although it doesn't seem to allow it to be used for anything other than DOS applications (I don't get a speaker icon in the system tray), there is a break in the noise when I click on certain things in Windows, as if its responding somehow. The games themselves were tested in DOS mode. Set blaster is set properly in autoexec as well.
I've never dealt with sound hardware this old, so I don't know if I'm just doing something wrong, or if there is some kind of defect with the card. A defect is certainly possible, considering that the card had its volume knob harvested at some point, but I'm not sure where to go from here. I thought maybe it was because I was using a stereo mini jack and the SB 2.0 is only mono that it was having some kind of issue there, but even with a 3.5mm mono plug, connected to one side of an RCA to 3.5mm stereo Y cable, I get the same problem.
Are there any common failures with these? I should be able to replace just about anything on one of these since the components are so large and accessible.
EDIT: A little bit more info...
The volume knob does effect the level of static I get, so the pot seems to be fine there.
I did a super technical "sniff test" after running the card, to tell if any components may be fried... and to my surprise, the TEA2025B in the middle of all the electrolytics near the card's inputs and outputs has a faint but distinct smell of burnt electronics. There isn't any visible damage, and this appears to be the amplifier that runs the speaker output, so I'm inclined to think that someone probably just pushed the poor fella too hard at some point (hooked it up to some large speakers with low resistance maybe), fried it and then threw it back in the box, only to harvest the volume knob some time later.
I may have one of these chips, but if I don't, are there some common chips that are compatible? I could probably just steal one off a less interesting sound card of course... but I've got a few sacks of old DIP chips of various types and I may have a compatible replacement ready to be used.
