i use a similar part to reset my replacement bally MPU and the -51 sound board. Simple, cheap, and they work well.

I'm not sure its worth doing it to a SYS11 MPU unless all those parts got puked on by the batteries.

You could even just cut out the reset generator parts and whack it across the 6802 legs. Could probably even hide it under the CPU socket or on the back of the board. Reset gen just hooks up the gnd +5v and the /reset. P1, P7, and P40 of cpu

i'm not sure where jokerz was at with moving the sound stuff to a separate board, but don't forget about the sound board. It has its own CPU and support parts, including reset.

The hum buzzing you hear is probably from the capacitors taking time to charge up, but not sure about the digital noises. If everything else works and is stable, i'd probably leave it alone.

I will say my F-14 is pretty silent until at power on. I put all new electrolytic caps in it maybe 6-8 years ago.

revisted the schematic in f-14 and it does show the /reset from the MPU going across the ribbon to the sound board. also triggered a memory that some of the early sys11 (plain / no letter?) that didnt have /reset hooked up right going to the sound board, but my mem is foggy. Which sys 11 MPU are you using?

you can stick a logic probe on /reset past the sound ribbon and make sure it is making it to the sound board. Probably jumper W1 on the sound board is /RESET.

I am about to do this mod on an Elvira board that was destroyed by battery corrosion. However, I cannot find the correct part. I can get an MCP120-450GI/TO easily enough (450GI instead of 460GI). Are these parts interchangeable or do I need the 460GI?

450 should be a fine replacement. the final three numbers indicates the voltage trip point where it puts the processor into reset. 450 = 4.5v0dc max and 460 = 4.60vdc max. The GI or DI letters indicate the pin out arrangement. TO indicates package type (i think). See the datasheet for pin out.

My go to reset part is MCP130-460DI/TO They are usually in stock at Arrow and other places.

Great fix for a whole lot of extraneous crap that is no longer needed on these boards.

The 450 gives a bit more of a hysteresis zone than the 460. Sometimes the low voltage dips are merely noise on the 5V line, more hysteresis will reduce triggering on noise. If you have a good, solid 5V line then either will work fine.

Note that there is already a pullup on the reset line via resistor network pack SR19, pin 3. So for this one an MCP120 would be preferred. But if you were to use an MCP130 then that would work as well -- but the reset generator would need to pull down two load resistors (still an easy task).

Thanks for the response, guys. A second question: the part I am looking at is DI/TO instead of GI/TO (https://au.rs-online.com/web/p/products/7240586/). Is the pinout the only difference with DI vs GI? Any other differences I need to think about?

just the pin out is different. two pins are rotated. they call it the die bond out i think if you check the datasheet.

Note that if you get the part with the different pinout - you need to modify the pinout arrangement as presented in the video to match.
The "G" part versus the "D" pinout is a rather radical pinout change.

Understood. You guys are right, the pins are totally different. I will install it opposite to the direction illustrated on Pinwiki to line up the reset pin with the top pin of Q39. Then I'll have to bend the other two pins so that negative (VSS) goes to the middle pin of Q39 and positive (VDD) goes to the bottom pin of Q39.
Capture (resized).PNG

Just installed the new reset generator. It's a bit fiddly rearranging the pins to match the pinout, but it works OK.

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So, silly question, but is D2 still required when using the reset generator? It is not stuffed in this pic on Pinwiki which shows the minimum parts required when using a reset generator: https://www.pinwiki.com/wiki/index.php?title=File:Sys11_Battery_Rot_Done.JPG

But it is still required for the batteries? I am getting an adjustment failure message but that might be because I did not stuff D2. But I didn't think anything of it because it was not on the parts list on Pinwiki.

Thanks for any advice.

If you are using batteries D2 must be installed or the batteries will not keep the RAM contents intact when the game is turned off.

I thought so! Thanks.

Any other components necessary for the battery?

Looks like there was never a follow up to this, can anybody clarify, what all components can be removed for system 11

Also can a link to the 3-7 be posted here? Thanks