CoindoorDave
Well-known member
Help needed - troubleshooting sound (Atari & the MB3717 amp)
OK - should have left well enough alone this weekend, but didn't. Had my Atari Arabian working perfectly except the sound was a bit "tinny". For short-term fix I ran the Speaker +/- lines thru an amp I pulled from a set of PC speakers.
Still sounded "tinny" to me.
Swapped out the AY-3-8910 with a couple known working ones and no diff. Ordered a new MB3713 from Bob and carefully removed the old one and then soldered in the new one..........backward....doh! As a result - there was NO sound.
Removed the MB37137 (assuming its toast, but set it aside) found a donor (off sound board from a Kangaroo set, which was missing the CPU board). Same chip - the MB3713 (not the MB3712, which I also have on another PCB). This time I was careful in making sure it was added correctly. No sound still.
Replaced the electrolytic caps that the MB713 output to (according to the repair guide/manual I found online for the game). Nothing. (and I made sure I replaced the caps with new ones with the same value).
Measured the +12 coming from the PS (it's fine). But haven't checked it on the board (so maybe there's something else friend).
I tried hooking the speaker lines back to the external amp, and also directly to the speakers. I get hum from the speakers (and actually I can hear a faint radio station being picked up).
Any suggestions on what to try next? I really wanna finish this - so close; cabinet's fantastic, got a new repro CPO and new yellow leaf buttons, shined up the shaft on the original red ball joystick - even replaced the badly burned G07 with a newer WG monitor with a fantastic picture and virtually no burn-in.
Thanks!
OK - should have left well enough alone this weekend, but didn't. Had my Atari Arabian working perfectly except the sound was a bit "tinny". For short-term fix I ran the Speaker +/- lines thru an amp I pulled from a set of PC speakers.
Still sounded "tinny" to me.
Swapped out the AY-3-8910 with a couple known working ones and no diff. Ordered a new MB3713 from Bob and carefully removed the old one and then soldered in the new one..........backward....doh! As a result - there was NO sound.
Removed the MB37137 (assuming its toast, but set it aside) found a donor (off sound board from a Kangaroo set, which was missing the CPU board). Same chip - the MB3713 (not the MB3712, which I also have on another PCB). This time I was careful in making sure it was added correctly. No sound still.
Replaced the electrolytic caps that the MB713 output to (according to the repair guide/manual I found online for the game). Nothing. (and I made sure I replaced the caps with new ones with the same value).
Measured the +12 coming from the PS (it's fine). But haven't checked it on the board (so maybe there's something else friend).
I tried hooking the speaker lines back to the external amp, and also directly to the speakers. I get hum from the speakers (and actually I can hear a faint radio station being picked up).
Any suggestions on what to try next? I really wanna finish this - so close; cabinet's fantastic, got a new repro CPO and new yellow leaf buttons, shined up the shaft on the original red ball joystick - even replaced the badly burned G07 with a newer WG monitor with a fantastic picture and virtually no burn-in.
Thanks!
