Tandy 3 Voice Sound - SN76489 ISA Soundcard Project \ VOGONS

i wanted to build a lotech Tandy Soundboard, unfortunaly James is not longer selling any boards on his page.
Does anyone own a Spare Board and can Scan both Sides in High Resolution to allow me to build my own ?
EDIT: I'm a idiot.. james already has pictures in high res on his side.
EDIT: Ok backside is missing... 😒
i have already all components laying around.. just missing the pcbs.

should not a hard task to reengineer the pcb.

Maybe someone can help me out ?
i can also trade i still have lotech isa compactflash pcbs.
and rs232 to ps/2 converter pcbs.

Thanks

Matthias

EDIT:
Hotfixes for LO-Tech Audio Combatible Sound Adapter and R0 and R1 Tandy 3 Voice Boards:

Tandy 3 Voice Sound - SN76489 ISA Soundcard Project

Last edited by matze79 on 2023-05-17, 22:00. Edited 10 times in total.

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Reply 1 of 456, by sirlemonhead

Posted on 2017-06-02, 18:29

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Did you contact him? I noticed he's not selling anything at the moment but did he say he's stopped altogether?

Thought he might be receptive to release schematics/files if he's no longer interested in selling PCBs...

Reply 2 of 456, by matze79

Posted on 2017-06-05, 13:53

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yes already did contact him, does not answer anymore.

i found a old schematic.

Tandy-Sound-Adapter-r01.png

but i dont know if its the same version like the pcb from the store.

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Reply 3 of 456, by matze79

Posted on 2018-01-20, 20:15

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tandy.jpg

During my holidays i made some progress..
maybe soon i etch a pcb.

still need to check adress decoder, i'm never have designed one... and have no exact idea how they work.

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Reply 4 of 456, by dreamblaster

Posted on 2018-01-20, 20:20

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nice !
if you need some help, just pm me

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Reply 5 of 456, by matze79

Posted on 2018-01-21, 14:44

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Thanks 😀

test.jpg

found some spare time.. need a break now 😁

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Reply 6 of 456, by bjt

Posted on 2018-01-22, 12:59

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I have a populated (not working) Lotech Tandy board if it would help you.

Didn't spend too much time troubleshooting it because I have another working board.
You can have it for the price of postage. I suspect it might have a bad via.

Reply 7 of 456, by matze79

Posted on 2018-01-22, 13:59

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Thanks i send you a PM, that would really help me 😀

i'm testing some stuff with the Soundchip and a AVR currently (muting noise)
The MCU is only 50 Cent, also why not use one.
Programming is also no problem at all. Just adding a ISP Header.
And a ISP Adapter is today 1-2$ delivered from HK/CN.

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Reply 8 of 456, by bjwil1991

Posted on 2018-01-22, 20:13

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bjt wrote:
I have a populated (not working) Lotech Tandy board if it would help you.

Didn't spend too much time troubleshooting it because I have another working board.
You can have it for the price of postage. I suspect it might have a bad via.

I purchased one last year on eBay, and it sounds amazing. Guessing you got one on eBay yourself?

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Reply 9 of 456, by matze79

Posted on 2018-01-23, 15:41

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the Schematic above is really outdated, and CE never does anything with that Decoder at C0h.

I redraw something from the Pictures, James seems to use Top Plane as VCC.
As Capacitor on the Image has + connected in the top layer.

tandy_decoder.png

i used the images from lotech cards i found on the net and draw this..
Maybe some one with a Card can confirm it.

My Clock Divider is working fine and also my Tandy Chip is connected right.
The Picture of the ISA Card (Perfboard) is wrong rewired it.

So the only remaining thing is the decoder 😀

And here my LanCable WireMess:

messcard.jpg

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Reply 10 of 456, by matze79

Posted on 2018-01-29, 15:57

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Adress Decoder is working now, Card is playing Sounds 😀

Thanks to everyone helped.

Now i have 2 working Boards.

Now its time to get the Noise on Power up fixed 😁

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Reply 11 of 456, by matze79

Posted on 2018-02-02, 11:18

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Here a Picture of the working Card:

DSC_0099 (Large).JPG

i working now on getting the Sound IC muted on Boot Up 😀

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Reply 12 of 456, by matze79

Posted on 2018-02-02, 15:54

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breadboard test for muting 76489 successful.

Added 74HC244 to the perfboard build, allowing me to cut the 76489 from isa bus to send commands with mcu.
Had some issues, but turning down Busspeed to 4.77Mhz fixed them 😀

test1.jpg

Tomorrow is MCU Time 😁

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Reply 13 of 456, by Great Hierophant

Posted on 2018-02-03, 04:47

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Great progress, keep up the good work!

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Reply 14 of 456, by matze79

Posted on 2018-02-03, 13:27

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mcu_tech.jpg

MCU is wired up.

Now its time to get a Idea howto get it work..

Need still to cut off some signals (CE/IOW/etc)

Pass them Trough MCU ? hmm

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Reply 15 of 456, by matze79

Posted on 2018-02-05, 11:07

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With MCU passthrough i get timing issues, even if i do use asm hmm.
And another Amp or Transistors to switch off would raise the part count up..

EDIT:
Stupid Idea, content removed.

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Reply 16 of 456, by matze79

Posted on 2018-03-03, 13:34

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muting_Ready.jpg

photo_2018-03-03_14-26-05.jpg

Got it!

Muting now works.
The Card is now silent on Bootup.

A RS Flip FLop did not work well for me.
Some BIOS seem to access second DMA Controller, so running the Card on AT (0C0h) can cause the Flip Flop to Trigger on Boot..

I'm using a ATTiny13 now.

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Reply 17 of 456, by keropi

Posted on 2018-03-03, 14:18

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excellent news!

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Reply 18 of 456, by dreamblaster

Posted on 2018-03-03, 19:20

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Super news !

Reply 19 of 456, by matze79

Posted on 2018-03-11, 12:08

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Current Progress:

tandy_check.jpg

Now i'm Searching a way to reset attiny on System Reset.

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