Pin-bot no background music

[lozpeters]

Ok i have been tinkering with this for the last few days trying bits out to try to solve it myself but now i am stuck

So my Pin-bot has no sounds or music at all. No noises at start up, no noises during tests and nothing if i push the CPU test switch.

I have been testing continuity and all seems fine, re-seated all chips and connectors. twiddled the volume control switch and nothing (does make the speakers crackle when i twist it)

Checked the voltages on the power board and i get 5v, +12V and -12V. The sound board is getting 5V and +12V @ J3 (should i have -12V here too???)

So now i am confused, what should i test now?

 

[lozpeters]

ok, after a bit more digging, pin 8 on the mpu is reading +5v according to flipperwinkle this should be -12v!! and powers the sound, i will do some more digging and see if this is incorrectly wired or a fault in the -12v coming from the power board

 

[Jay Walker]

Hi,

According to the schematics, pin 8 of the 6802/6808 mpu chip(s) should be a steady 5v. The only correlation between -12v and a 'pin 8' I can see is the mpu board power input connector, 1J17. And the audio pcb should receive 5v and -12v, but not necessarily +12v. If the power input to the audio board, J3, has only 4 pins, they're 5v (Grey), Ground (Black), -12v (Black-white) and a keying pin, pins 1 to 4, right to left. If +12v is supplied, it would be at pins 5 & 6 of a 6-pin connector at J3, with White-grey wires. Though that type of audio pcb has two audio amplifiers, I don't think they're actually used. The audio signal is amplified and sent to the speakers by the amp on the mpu board.

 

[lozpeters]

thanks for that Jay, it is the 6 pin connector.

I swapped the wire on the MPU to a -12v line on the power board ( so now the sound board gets -12v +12v & +5v)

i now have sounds the machine bongs once when turned on, and in test mode i get sounds but no music and when i push the MPU test switch i just get one sound (like a muted symbol)

so getting there just some more digging to get music to work!

 

[lozpeters]

OK a little update now i have had some time to play

one bong when i turn the machine on, all sound affect tests work fine. The music test gives nothing. If i push the CPU test switch i get one tone, which according to the flipper wiki is a bad RAM at U23 should i change this and where is the best place to get one??

Also i noticed while the machine is on and in attract mode after a min or 2 it says "i see you" then after another min or 2 i do get some music playing

so why does it seem to play music in attract mode but not the test mode??

any help much appreciated