appiah4 wrote on 2020-07-10, 21:19:

There is certainly +5V and -12V elsewhere on the card, I can measure them on Pin 4 and Pin 11 of U11, for example. However, there is still no +5V on Pin 14 of U12. There is +5V on the +5V side of R38, but the side that is connected to Pin14 shows no voltage, it is shorted. When I remove the DAC at U12, I can measure +5V at Pin 14 of the socket.

Could be pins 14 and 15 got shorted somehow, you could measure continuity of the socket. Take out the DAC and measure the resistance between pin 14 and pin 15 on the IC as well, and between pin 14 and pin 2. If the chip has a short then it's bad. If the chip was ever installed backwards, it's bad.

You might also have a power supply that is going bad. Check the capacitors for evidence of leaking electrolyte, and measure the ripple voltage on each supply voltage rail. You can do this with a multimeter set to AC volts.

Also check your Snark Barker for any electrolytic capacitors that are in the wrong way around. If there are any that were in backwards, they need to be discarded and replaced.

TubeTimeUS wrote on 2020-07-16, 17:21:

Could be pins 14 and 15 got shorted somehow, you could measure continuity of the socket. Take out the DAC and measure the resist […]
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appiah4 wrote on 2020-07-10, 21:19:

There is certainly +5V and -12V elsewhere on the card, I can measure them on Pin 4 and Pin 11 of U11, for example. However, there is still no +5V on Pin 14 of U12. There is +5V on the +5V side of R38, but the side that is connected to Pin14 shows no voltage, it is shorted. When I remove the DAC at U12, I can measure +5V at Pin 14 of the socket.

Could be pins 14 and 15 got shorted somehow, you could measure continuity of the socket. Take out the DAC and measure the resistance between pin 14 and pin 15 on the IC as well, and between pin 14 and pin 2. If the chip has a short then it's bad. If the chip was ever installed backwards, it's bad.

You might also have a power supply that is going bad. Check the capacitors for evidence of leaking electrolyte, and measure the ripple voltage on each supply voltage rail. You can do this with a multimeter set to AC volts.

Also check your Snark Barker for any electrolytic capacitors that are in the wrong way around. If there are any that were in backwards, they need to be discarded and replaced.

Thanks TubeTimeUS. I have checked and all electrolytics are correctly oriented. The DAC was inserted the wrong way once before though, no wonder ir t is apparently bad now..

Anyway, I ordered replacements for the DAC, Amplifier and bus transceiver from a third supplier and they came in today. Replaced them all.

Also managed to find some 270pf/63V ceramic caps and replaced the 270pf/1kV ones I had on C68/C65 (which I kind of suspect are the cause here: prpbably low capacitance at 50V...). I will check and report tonight.

appiah4 wrote on 2020-07-20, 18:37:

Thanks TubeTimeUS. I have checked and all electrolytics are correctly oriented. The DAC was inserted the wrong way once before t […]
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TubeTimeUS wrote on 2020-07-16, 17:21:

Could be pins 14 and 15 got shorted somehow, you could measure continuity of the socket. Take out the DAC and measure the resist […]
Show full quote

appiah4 wrote on 2020-07-10, 21:19:

There is certainly +5V and -12V elsewhere on the card, I can measure them on Pin 4 and Pin 11 of U11, for example. However, there is still no +5V on Pin 14 of U12. There is +5V on the +5V side of R38, but the side that is connected to Pin14 shows no voltage, it is shorted. When I remove the DAC at U12, I can measure +5V at Pin 14 of the socket.

Could be pins 14 and 15 got shorted somehow, you could measure continuity of the socket. Take out the DAC and measure the resistance between pin 14 and pin 15 on the IC as well, and between pin 14 and pin 2. If the chip has a short then it's bad. If the chip was ever installed backwards, it's bad.

You might also have a power supply that is going bad. Check the capacitors for evidence of leaking electrolyte, and measure the ripple voltage on each supply voltage rail. You can do this with a multimeter set to AC volts.

Also check your Snark Barker for any electrolytic capacitors that are in the wrong way around. If there are any that were in backwards, they need to be discarded and replaced.

Thanks TubeTimeUS. I have checked and all electrolytics are correctly oriented. The DAC was inserted the wrong way once before though, no wonder ir t is apparently bad now..

Anyway, I ordered replacements for the DAC, Amplifier and bus transceiver from a third supplier and they came in today. Replaced them all.

Also managed to find some 270pf/63V ceramic caps and replaced the 270pf/1kV ones I had on C68/C65 (which I kind of suspect are the cause here: prpbably low capacitance at 50V...). I will check and report tonight.

Man, I hope that this fixes the final problems so you can enjoy the card 😀

After replacing the caps and the ICs, the behaviour is still the same: Distorted digital audio and no +5V on the new DAC chip's Pin 14. Pin 14 has continuity to R38, there is +5V voltage between one side of R38 and Ground and there is 0V between the side that is connected to the DAC and Ground. When I measure R38 to check its resistance I get 2.7K Ohms. Pin 14 is not shorted to Pin 2 on the DAC. Pin 14 is somehow NOT getting voltage, though. How come? I'm so confused..

Also, in case this helps, another strange behaviour I noticed is when I run Duke3D, sound effects can get 'stuck', i.e. keep repeating until a new sound effect comes along (the plane's passing by sound loops until I blow up the fuel tanks, etc.)

I'm starting to think maybe the DSP is bad at this point? But that doesn't explain missing +5V Vref on the DAC.. *SIGH*

Today I released SBDIAG (https://github.com/schlae/snark-barker/tree/master/sbdiag) which is a diagnostic utility for Snark Barkers and Sound Blasters. It makes no assumptions about a working card and can help with hardware-based troubleshooting for folks who have logic probes, oscilloscopes, or logic analyzers.

Thought maybe some of you could use it for troubleshooting cranky Snark Barkers.

Much appreciated thank you. I will give fixing my card another go in a few weeks, this should come in extremely handy!

One thing I am wondering: was the firmware of the original SB 1.0, 1.5 or 2.0 ever dumped? I would love to swap those out with the SnarkBarker firmware. I have one CT1351 chip here, in PLCC packaging, but couldn't dump its contents. I guess it is protected?

root42 wrote on 2020-09-01, 09:25:

One thing I am wondering: was the firmware of the original SB 1.0, 1.5 or 2.0 ever dumped? I would love to swap those out with the SnarkBarker firmware. I have one CT1351 chip here, in PLCC packaging, but couldn't dump its contents. I guess it is protected?

I'm not sure if this answers your question, but I've got a very old non name SB clone that looks and acts like a SB 1.5 or 2.0..
Unfortunatelly, I'm unable to dump the contents of the microcontroller, because both the G540 and the TL866 that I've got are too primitve to support
8051, 8042 and similar oldschool microcontrollers. For this, I would need some Galep or similar professional programmer, I'm afraid. 🙁

I have a Galep 3. I tried reading the CT1351 with it, but it returns only FF. I may have chosen the wrong Intel MCU though. Or it is read protected.

root42 wrote on 2020-09-01, 11:51:

I have a Galep 3. I tried reading the CT1351 with it, but it returns only FF. I may have chosen the wrong Intel MCU though. Or it is read protected.

Didn't TubeTime have a huge blog post about how he encountered this same issue and went about solving it, which included resorting to an X-Ray microscope or something?

I dunno. Maybe? However his firmware is from a SB clone. So I figured he never succeeded.

The original MCUs are all protected. Some microsurgery would be needed to defeat the protection from what I know, chip gets decapped and protection mechanism gets disabled with laser or such.

Darn. Would have been too nice to have a dump 😀 I guess no one ever tried that? Or Creative probably had the images taken down pretty quickly...

I'm sure there have been attempts but nobody has succeeded, me included 🤣

The X-RAY thing I remember is here in this PDF: https://hardwear.io/usa-2019/presentations/So … io-usa-2019.pdf

This was an awesome read/look 🤣 !

Yeah it's a hillarious read.

I'm so salty that I still haven't resolved my card's PCM issue 🙁

Short of trying a second MCU I basically replaced every other component on the PCM circuitry.

What kind of programmer do I need to program the Atmel? Maybe I should try reflashing it..

That, or one of the sockets I used is faulty in a way I can't tell (I checked every chip leg to the solder point of the socket..), or one of the passives or the board are bad somehow, since they are all correct values..

I tried out the diagnostic utility but without a probe or oscilloscope I didn't get very far. I'm at the point I'd be OK with just mailing it out to whoever would want to try their hand at fixing it..

appiah4 wrote on 2020-09-02, 11:24:

What kind of programmer do I need to program the Atmel?

If it's 89S51 (or other chip with serial programming) you can use arduino. https://www.instructables.com/id/Program-8051-With-Arduino/

Yeah it's a 89S51.. I will look into the arduino way. Any other programmers you can recommend?

root42 wrote on 2020-09-01, 09:25:

One thing I am wondering: was the firmware of the original SB 1.0, 1.5 or 2.0 ever dumped?

In 2019 TubeTime say in his twitter :

today i was able to confirm that i have a bit-accurate dump of the Sound Blaster CT-1351V202 DSP 2.02 firmware!