Game was working fine then one day decided not to boot. The -17 MPU LED does not flicker; just comes on solid at power up. The brown sockets have been replaced and there is no corrosion on the board.

I replaced U7 through U11 with known good chips and nothing changed. Solid LED, so assumed the game ROM's were bad.

I modified/jumpered the -17 board to accept two 2732 ROM's and purchased a set for Evel Knievel. Tested them in another board, so they are good.

Now, I have installed only U6, U9, and U11, all known to be good. No flicker, only solid on.

I briefly shorted U9 pins 39-40. LED stays solid on.

Can I get some troubleshooting help? ...looking for a flicker! Thank you...

I have also checked continuity from U9, U10, and U11 pins. I don't find any openings or shorts.

There is no corrosion. The reset is working properly.

To be clear, this was summarized in my first post this posting.

I have double and triple checked the new socket soldering (see post #2). The jumpers in piniwiki are correct. I have modified another -17 board for 2-2732 ROMs and that board is working.

Ballypin, you're an EM guy!!!

A while back I bought the NVRAM.WEEBLY.COM Universal MPU board (instead of Alltek) and couldn't be happier. The price was better, and Andrew has been helpful through the years. It has been a good product.

I don't need another MPU. I already have two working spares, but I'd like to get this one from Evel Knievel working again then add it to my spares collection.

Yes. At power up it starts low and goes to 5v in split second. And when I short pin 39 and 40 momentarily the LED stays lit. I'm assuming the reset is working correctly.

OK....they are all pulsing. For what it's worth, I checked all the pins on U9. In addition to the ones you listed, pin 3, 5, 36, and 37 also have pulse activity.

Also, I don't know how to interpret this: All the pins showed steady pulse and steady level (probe green LED), but pins 22 thru 26 showed a quickly flickering level (probe green LED) instead of a steady (non flickering) level.

They are.

Added back in U11 and same activity.

Added back U6. Observed different activity. All pins on U9 pulsed as before EXCEPT pin 5. It does not pulse.

U9 pin 5 measures 4.21
U15 pin 3 measures 2.54

U9 pin 5 is not pulsing with U6 in. It is pulsing with U6 out.

yes. But just to check, I swapped it out again for a new one, tested in another game.

U19 pin 10 pulses with U6 out, and does not pulse with U6 in.
U15 pins 4,5 and 6 pulse with U6 out. With U6 in, pin 4 does not pulse, but 5 and 6 do.

U9 pin 5 measures 4.13 v with U6 in, and 3.7 v with U6 out.

U6 pin 18 has continuity with pin 12, and briefly with pin 24. Pin 18 is jumpered to pin 12 per the jumper instructions (for -17 board to run two 2732 ROM's). And when I check for continuity from pin 18 to pin 24 I get a split second of continuity, then infinity.

I also pulled the U6 socket frame off the board to look underneath and inspect the pins. It is immaculate. No trace issues whatsoever, no solder bridges.

No

In checking the resistance between pins 18 and 24, I measure 500 ohms with my leads one way, and when I reverse the leads I measure 1k ohms. These measurements are consistent and repeatable.

Reading pinwiki and locked on LED says to check U9 pin 5 (VMA line) and I should get about 2.8V. In my case, I get 4.14V. Says if incorrect try a new U9, which I did. Then says to check U14D, U15C, U19B. U15 most likely IC to fail. My question: What am I supposed to be checking for on U14D, U15C, and U19B? Or is there something else you see with regards to the previous posts and measuring data?

U15 pin 3 -- I get a pulse with and without U6.

I get pulsing activity in all pins except 12, 18, and 24.
I do get pulse at pin 22. I also get pulse at 18. Per the mod, the trace to pin 18 is cut and a jumper is connected from pin 12 to 18.

I stepped through logic probe U14, 15 and 19. I get no pulse at U19 pins 8, 9 or 10, and U14 pins 11 or 12.

I have triple checked all the jumpers.

I will continue prying up socket frames and continuity checks. I have checked and double checked the work around U9, 10, and 11 and find nothing. The thing I keep coming back to is that this board was locked up before the sockets were replaced, so I think it's something that is (was) untouched.

I rechecked voltages and pulse activity on Andrew's drawing with U6 in and out. Here are the results. (NP=no pulse, P=pulse).

Screen Shot 2020-09-01 at 11.28.52 AM (resized).png

No. It didn't work before I changed the jumpers either.

Is it significant that U19 pin 10 and U14 pin 11 voltage is low?

yes, and your point?

Yes, it worked up until the day it quit working. When it quit the LED was locked on. I just figured the old brown sockets should finally be replaced, U9 U10 and U11. The other sockets are not brown. So I replaced the 3 brown sockets and nothing changed. LED still locked on.

Then I replaced U7, U8, U9, U10 and U11 with known good chips and nothing changed. LED still locked on. So I figured the U2 and/or U6 went bad and bought two replacements....them being 2732's, so I did the jumper mod for the -17 board to accept two 2732's. I had done this mod on another -17 board recently and it worked fine.

Did the mod and installed the U2, U6, and all the others. Still LED locked on.

I never get a flicker.

So to answer your question, yes and no, the board worked before I did the jumpers (like when the board was new in 1979), but it quit working before I did the jumpers.

Don't know how I'd ever burn my own eproms when I don't even understand all this PROM, EPROM, ROM stuff! Bob, you're killing me!

So, I don't know. I had two original ROM's in U2 and U6. I bought replacements, U2 and U6 both 2732's. I tested them in a -35 board I have jumpered for 2732's and the board booted. So I believe I have two good 2732's for U2 and U6.

Not sure what you mean "2732s were 2716's doubled up." I didn't have files combined onto a single chip if that is what you are referring to.

I did the jumper mod as shown here, including the cuts and jumpers in section D.

I have quadruple checked that the jumpers are correct.
Screen Shot 2020-09-02 at 11.01.05 AM (resized).png

OK...that sort of makes sense.
I've asked Andrew to chime in regarding exactly what he burned for me. Maybe the next step will be to try the different jumper settings. Will kinda suck as I have cut some of the traces for the 2732's, but no big deal if that solves the problem.