Asteroids audio hum shown on an oscilloscope

Video shows the 10.3 v unregulated supply and speaker outputs measured with a volt meter and with an oscilloscope.
UPDATE: I finally got around to ordering the TDA2002 audio amps and replacing both of them on my Asteroids AV board. The new amps made a huge improvement in reducing the persistent hum. Before changing the amps, when the machine was turned on, I would hear a loud hum for a few seconds along with the crackling sound of the fluorescent bulb turning on. The hum would then get lower but was always present. After changing the amps, I still hear the crackling sound of the fluorescent bulb turning on but that loud hum is gone! There is still a little hum with the machine turned on, but it is the normal, acceptable hum of the machine.
I purchased 10 of the TDA2002 amps from China for around $6
www.aliexpress...
When using an ohm meter on the 2M scale and measuring the TDA2002 out of circuit from pins
1 to 2
2 to 3
3 to 4
4 to 5
the new amps read OL (open)
one of the original amps also reads open across those pins
the bad amp reads
1 to 2 = 260k
2 to 3 = 48k
3 to 4 = 22k
4 to 5 = 20k
Here is the link to the Vintage Arcade Forum where I discuss problem solved with my Asteroids machine...
forums.arcade-...

[@JeffFriedrichs]

Did you ever figure this out? I am having a similar problem

[@georgeterbush2976]

Yes. The hum in the audio turned out to be a bad TDA2002 audio amp on the Asteroids AV board. I replaced both just to be on the safe side. I just updated the description above with the details. Good luck!

[@JeffFriedrichs]

@@georgeterbush2976 Thanks - sadly replacing the TDA2002s did not fix my problem

[@georgeterbush2976]

@@JeffFriedrichs That's a shame. Before changing the amps, I spent weeks going over and cleaning up the ground connections on all of the boards, power brick and monitor. Nothing helped until I changed the TDA2002's.