PhilsComputerLab wrote:

firage wrote:

could be a broken solder joint.

That's something I would try. If you have a solder iron, heat up every solder joint.

I did this with a non-working GUS PnP and it came back to life 😀

My SB32 CT3670 has a broken solder in the speaker out connector. I can see it (big crack) and the
connector is loose. Thanks to it, I lost one channel.
The Line out is fine, but it does not amplify the output. I got to fix the speaker out...

Solder iron ? There are some obstacles in the way.
Removing the speaker out connector doesn't look good to me.
Hot air (400C degrees) maybe ?

Damn ! I feel dizzy again trying to grasp terms like scope and TO92 5V regulators 😠
Is this a component with three legs ? I just don't want to hurt my SB32 learning stuff !

Frasco wrote:

Damn ! I feel dizzy again trying to grasp terms like scope and TO92 5V regulators 😠
Is this a component with three legs ? I just don't want to hurt my SB32 learning stuff !

"Scope": oscilloscope
"TO92 5V regulator": yes, a small three legged component like a transistor, but with markings like 7805 or 7905 (possibly another component number, since I haven't checked my CT3600 yet)

Frasco wrote:

My SB32 CT3670 has a broken solder in the speaker out connector. I can see it (big crack) and the
connector is loose. Thanks to it, I lost one channel.
The Line out is fine, but it does not amplify the output. I got to fix the speaker out...

You should be able to reflow the pins on the back with an iron.

devius wrote:

"Scope": oscilloscope
"TO92 5V regulator": yes, a small three legged component like a transistor, but with markings like 7805 or 7905 (possibly another component number, since I haven't checked my CT3600 yet)

7805. Thanks for your readness. Total safety now!

Uh...Oscilloscope. Kinda like a multimeter and it also serves to test components.
Please, don't waste your time explaining details cause I don't have such equipment.
It looks like an important and advanced troubleshooter.

gdjacobs wrote:

You should be able to reflow the pins on the back with an iron.

Awesome! And doing a small pressure of course.
Let's try it again.

Frasco wrote:

gdjacobs wrote:

You should be able to reflow the pins on the back with an iron.

Awesome! And doing a small pressure of course.
Let's try it again.

Yeah, hold the jack in place when you touch up the solder joints.

My right channel is back after 17 years.

I was too scared (never did it before) and I had some minor problems.

The solder wasn't going in the right place, so I used a small cooper wire
and finally the solder slipped in the crack.

And then the multimeter beeped continuity. I was like: Fantastic!

So yeah, just another accurate information from you, as usual.

SB32 isn't that great, but I remember the day I got this one, thinking: It's time to play
DOOM 2 in all glory!

Maybe have a look at some of the games on this list.
MS-DOS AWE32 Games list

You'll want to source some RAM to install first, of course. Let us know how it works for you!

Took heed and found this one:

JESUS ! I still remember the CD music (orchestral). No such joy if you get some ripped version.
The art aged, but it has a special place in my heart.

Crusader and Blood 😀 😀
I still remember guards burning and crying ! Memories that remain.

Don't know if SB32 is the best for them. Although I plan to use it in some retro machine.

gdjacobs wrote:

You'll want to source some RAM to install first, of course. Let us know how it works for you!

What for ? I heard something about "soundfonts" to enhance SB Live! or AWE32.
It sounds like modification to me. I like the AWE32 the way it is, but I'd like to hear your opinion.

I believe titles that support uploading custom music samples to an AWE card will require it. This is essentially the feature that AWE cards including the SB32 and Goldfinch can give you over a Waveblaster II.

You are not the first to tell me about this benefit. When my friend said something about installing RAM, I imediatelly discounted it. 😊

I have two modules of 1Mb and two of 4Mb. What you say ?

30 pin SIMMs? Go big or go home!

But how can I get those memories ? 4Mb modules (30 pins) are hard enough to find.
Besides we are talking about DOS games.

Ah, sorry for the steal. That's my last intervention.

That's what I meant. You have 4MB SIMMs, might as well use 'em. If you find larger capacity ones down the road, do the upgrade.

James-F wrote:

Check the 5V and -5V regulators, they are fed from the 12V and -12V rails.

Tested them and they both output the correct voltages.

I then followed the audio path from the output back to the multiplexer chip and here's where things get interesting, and by interesting I mean bad. I used wires connected to powered speakers to try various points along the way to see if I could get correct audio somewhere.

The multiplexer chip is a 74HCT4053D. Here's a schematic of the chip:

I'm familiar with analog audio electronics, but I never used a multiplexer and don't really know what it's used for. One thing that puzzles me is that all the analog pins are described as input/output. I don't understand how a pin can be both an input and an output, but I'll try to find some information about that. Anyway, pin 14, that I traced from the card's output back to this chip, is silent, but pins 13 and 12 seem to be fine. Pin 13 is much more bass heavy than pin 12, but otherwise they seem to carry the same sound at the same volume. Asides from these, pins 1, 2 and 3 also carry correct audio, again with pin 1 much more bass heavy. I'm guessing the output to the other channel is either on pin 15 or 4 and these are all silent.

Now, the problem may be a damaged multiplexer, but it can also be one of the supporting components. Any ideas what to try next?

The multiplexer is like a set of two way switches. It connects pin 14 to pins 12 and 13, pin 15 to pins 1 and 2, and pin 4 to pins 3 and 5 depending on how the switches are programmed (via pins 9, 10, and 11).

So it's possible the multiplexer is damaged, but it's equally possible that it's not being programmed properly.

Have you tried jumpering across the switch to see what configuration gives you proper output?

Yeah, after reading the multiplexer's datasheet a little more I think I understand the input/output thing. The pins function as either input or output depending on how you use it. In this case it's used as a multiplexer, so pins 4, 14 and 15 are outputs. If it was being used as a demultiplexer these pins would be inputs.

At this point I'm almost certain the problem is the chip. All the DC voltages to its control pins seem correct. Pin 6, 9, 10 and 11 are LOW (0V), which means that pins 2, 5 and 12 are selected as inputs and there should be output on pins 4, 14 and 15.

Also, I took your advice and shorted pins 12 and 14, bypassing the multiplexer and got output out of the card on the left channel. Same thing with pins 2 and 15, but on the right channel. At this point I'm 99% certain it's the multiplexer that has gone bad. I'm going to try sourcing it locally so that I can repair the card faster.

Good plan.

I love electronics!
Especially troubleshooting and reverse engineering.

Alright, my CT3600 just came back to life 😁 I replaced the 74HCT4053 with another one from a AWE64 Value broken beyond repair. I had to buy a hot air station though, but I can already tell it's going to be extremely useful.

So, that's 2 CT3600 repaired thanks to this thread! Now, the only one left is the OP's. How's that going?