Sega Super Hang-On repair

Flocke28

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Hi all.. i got a faulty Sega Super Hang-On pcb.. it crashed on game start, menu showed a bad ram. I swapped the ram on ic128 and it boots again, but the road was missing.. so i found a faulty 74LS11 on IC52.. road is back agian.. but now on some background tilles is the transparency missing. Any hints?
 
Is this background a new issue or an existing issue?

The tilemap generator is on the bottom board, 315-597, IC67 page 8 of the schematics. I would piggyback TTL ICs in that area but make sure the ROMs (IC54, 55, 56) are good though.

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Failing that, I would consider sending it to Mark (retroclinic.com) in the UK.

p
 
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Ah. Thanks.. i bought the pcb in faulty condition, so i can't say which issue was the first.. bit i will check the bottom board.. great help
 
Now I realized that i get only fm synths but no pcm sounds 🥺 i checked the clock as good on the 315-5218, i found also a bad pcm eprom and swapped them, but no luck.. there is no activity on the address bus for the pcm eeproms and also no activity on the RAM address bus, also no write enable signals to the RAM, but OE signal is toggling for the ram.... the interrupt signals from the Z80 looks good.. i tried also a replacement PAL with no luck.. any hints? I hope that the 315-5218 itself is not faulty
 
I would investigate the Ram and DAC, you can piggyback the Ram with known good ones and notice any difference. You will likely need to power cycle the pcb when you piggyback the Ram.

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For the DAC, you will need an audio probe for the outputs.

Once you have eliminated those two areas, you can go "downstream" of the audio path, with the 4066 switch and MF6-50 filters. I doubt you have faulty filters (you would have to have them both fail).

My bet would be the RAM.

p
 
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I ordered some 6116 ram.. have to wait for it.. but i'm confused that there is no activity at all on the address bus.. so in my opinion it doesn't look like a ram issue.. or can't be a ram issue the sound chip stop working at all?
 
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I swapped the 2015 RAM (6116) but no luck.. still same issue, no activities on the sound ic.. seems the ic is dead 😒 .. but clk for z80 is there and some other signals like irg too..
 
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