Sound Blaster 16 CT1740 Problem

Discussion about old sound cards, MIDI devices and sound related accessories.

Sound Blaster 16 CT1740 Problem

Postby borgie83 » 2019-5-24 @ 08:22

Hey guys. So I have a Sound Blaster 16 CT1740 which was getting quite hot and also not playing sound out of the left channel. Due to this I replaced the Dac, Amp, Yamaha OPL Sound Chip and 2 larger capacitors located near the volume wheel. All with new parts. I haven't tested it yet as wanted to know if I should also replace the 2 voltage regulators first? Just don't want to power it up and fry the amp etc. Basically I'd like to know if the voltage regulators would cause a sound card to get hot and fry the amp.
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Re: Sound Blaster 16 CT1740 Problem

Postby borgie83 » 2019-5-25 @ 05:07

*Bump*
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Re: Sound Blaster 16 CT1740 Problem

Postby Jo22 » 2019-5-27 @ 04:34

Hi, not sure what to say. :( If an 78xx/79xx is faulty, it either shorts or passes the full voltage.
These voltage regulators aren't expensive and can be bought in your local electronics shop.
Just be sure to get the right parts. Some stabis can provide 0.5A, 1A or 1.5A (or 2A).
So also better check the suffix, (ex. 7805 vs 7805CT vs 7805G etc.)
Also keep in mind that pinout of 78xx and 79xx is not the same.
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Re: Sound Blaster 16 CT1740 Problem

Postby borgie83 » 2019-7-14 @ 01:37

Jo22 wrote:Hi, not sure what to say. :( If an 78xx/79xx is faulty, it either shorts or passes the full voltage.
These voltage regulators aren't expensive and can be bought in your local electronics shop.
Just be sure to get the right parts. Some stabis can provide 0.5A, 1A or 1.5A (or 2A).
So also better check the suffix, (ex. 7805 vs 7805CT vs 7805G etc.)
Also keep in mind that pinout of 78xx and 79xx is not the same.


Apologies for the delay. The voltage regulators are as follows; AN7805 and AN7809. Both appear to be positive voltage regulators? Could be wrong though. Just thought the sound blasters had 1 positive and 1 negative? 1st VR is 5V and the 2nd is 9V. Both 1A.
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Re: Sound Blaster 16 CT1740 Problem

Postby Jo22 » 2019-7-14 @ 22:00

Hi, yes, seems right to m. The older 8-Bit cards (SB1.x-2) also had -5v, I believe.
"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

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Re: Sound Blaster 16 CT1740 Problem

Postby borgie83 » 2019-7-18 @ 03:11

Jo22 wrote:Hi, yes, seems right to m. The older 8-Bit cards (SB1.x-2) also had -5v, I believe.


So 2 positive voltage regulators being a 7805 and 7809 would be fine to use? Also, is higher or lower ripple rejection better?
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Re: Sound Blaster 16 CT1740 Problem

Postby Tiido » 2019-7-18 @ 03:54

Higher ripple rejection is better.

Negative regulator is a small transistor sized thing (TO92 package), 79L05 written on it.
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Re: Sound Blaster 16 CT1740 Problem

Postby borgie83 » 2019-7-18 @ 13:39

Tiido wrote:Higher ripple rejection is better.

Negative regulator is a small transistor sized thing (TO92 package), 79L05 written on it.


Ok great. Thanks mate. What I'm confused about though is that my card appears to have 2 positive voltage regulators and yet I've read about there being 1 positive and 1 negative on Sound Blasters. I'll upload a photo on my voltage regulators for clarification.
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20190714_093915~2.jpg
CT1740 Voltage Regulators
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Re: Sound Blaster 16 CT1740 Problem

Postby Tiido » 2019-7-18 @ 14:13

5V one is for positive rails on the opamps and DAC+ADC stuff, -5V one for opamps negative rail and the 9V one is used for the speaker amplifier.
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Re: Sound Blaster 16 CT1740 Problem

Postby Jo22 » 2019-7-18 @ 21:54

Sorry for not replying ealier. Also: Good luck! :)
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