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Hi everyone

I have an Asteroids Deluxe board here that I'm unfortunately stuck with probing around and I could need help by pointing me into the right direction.

Trigger of the problem
When I turned it on, a TL08 exploded in the vector output. Now I have a permanently toggeling reset signal

I socketed L6 and lifted Pin 1 as suggested in this forum. --> Still a reset, but that means in the MPU section, correct ?
But the reset is not permanently toggling anymore, about every 4-5 seconds the signal now comes out of the watchdog circuit.

RAM test with Fluke 9010a

• RAM test 0000-01FF = OK
• RAM test 0200-02FF = OK
• RAM test 0300-03FF = OK
• RAM test 4000-47FF = RAM BITS 1 AND 4 TIED

When I write AA to 0x4000h I read back A8. So 1010 1010 get to 1010 1000, I see the lost bit but I can't make anything out of that information atm :-/

RAM test with Slice Tool (by Gadgetfreak)

• I tested both Ram + Vector Ram in circuit RAM = OK

ROM test with Fluke 9010a

• D1 (6000-67FF) = OK
• EF1 (6800-6FFF) = OK
• FH1 (7000-77FF) = OK
• DJ1 (7800-7FFF) = OK
  
  
• R2 (4800-4FFF) = ERROR
• NP2 (5000 - 57FF) = ERROR

ROM test in external Programmer show that all ROMS are okay.

I can't find any error in the address decoding circuit for example, something I'm clearly missing here. I am therefore happy about any tip that helps me in any way

Thanks and best regards from Hamburg, Germany,
Banane