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Doin' the Hacky POKEY


Nathan Strum

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Some time ago, I was planning to order a Concerto cart for my 7800.

 

I didn't have a POKEY to install in it, but figured I'd either order one from Best, or wait until the HOKEY was available to order the Concerto.

 

Around that same time, James mangled the daylights out of a POKEY, trying to remove it from a poor, unsuspecting Ballblazer cart. I offered to attempt to fix it, if he wanted to send it to me. So he did, presuming it to be DOA anyway (he subsequently bought a replacement POKEY from Best).

 

I didn't have anything to test it in though (and I wasn't about to mangle my own Ballblazer cart for testing), so I used the excuse of sort-of now having a POKEY to order my Concerto.

 

A year-and-a-half later, I finally got around to attempting to fix the chip.

 

Now, I didn't hold out much hope for success. I figured at best, I'd have a 30% chance of this working.

 

Thirty. Percent.

 

I think that was pretty optimistic, if you look at the pictures of the aftermath linked above.

 

When it arrived, I didn't think it looked all that bad.

01_mangled_pokey_front.JPG

 

Although that was the pretty side. This side...
02_mangled_pokey_back.JPG

Yeah. Ouch. It looks like James desoldered about 2/3 of the chip successfully, then just lost patience and tried ripping it out the rest of the way. (Just speculating... I'm sure James would never get impatient. :roll: )

 

So first things first - a little desoldering wick and some tweezers to clean-up and gently unbend the pins:
03_cleaned_up_pokey_front.JPG

 

So that all cleaned up pretty well, and just left me with one completely-broken-off pin, and one half broken one (third from the left):

04_cleaned_up_pokey_back.JPG

 

So to fix it, I decided to graft on a donor pin from another (dead) chip. I have a pretty-good collection of them now, from fixing up a few 2600's. Here's one from one of John's consoles:
05_donor_pins.JPG

 

For ease-of-access sake, I picked a corner pin that looked particularly stout, and chipped away at the resin with side cutters until I got a nice amount of the leg exposed:
06_top_pin_exposed.JPG

 

Then I broke off the chunk underneath. Neatness does not count here - I'm just making sure I don't damage the pin that I want.
07_bottom_pin_exposed.JPG

 

Then a couple of quick bends and presto! Donor body part!
08_donor_pin_clipped.JPG

 

Now I had to expose the top of the leg on the POKEY. I carefully scored the resin with a razor saw:
09_cutting_pokey.JPG

 

I had to be careful not to cut too deep and damage the part of the leg I needed to get to:

10_pokey_scored.JPG

 

Once scored, I figured I could just pop the piece off with a pair of side-cutters, as I'd done on the donor chip:
11_clipping_pokey.JPG

 

No such luck. I spent about 20 minutes gradually chipping and scraping my way down to metal:
12_pokey_exposed.JPG

 

Next, I cleaned and tinned the contact:
13_pokey_tinned.JPG

 

And used a spare chip socket to line up the donor. Sorry for the blurriness. iPhone 6S. (I refuse to upgrade.)

14_ready_to_solder.JPG

 

A quick touch or two with the soldering iron, and the leg was attached!
15_soldered.JPG

 

Next, I had to fix the half-broken pin (again - third from the left):
16_half_pin.JPG

 

I forgot to take a picture of clipping the donor pin off, so I craftily Photoshopped one. Nobody will ever be able to tell the difference!
17_donor_half_pin.JPG

 

I then forgot to take a picture of clipping off the broken half of the POKEY pin, and again was forced to show off my mad Photoshoppery skillz:

17b_clipped_pin.JPG

 

I used the socket again to line them up, and grafted the new pin on top of the old one:
18_half_pin_ready.JPG

 

Done!
19_half_pin_fixed.JPG

 

And the other side, because of course I remembered to take a picture of something I didn't need to:
20_front_of_fixed_pokey.JPG

 

So would it work? Remember - I'm giving myself a 30% chance of success, so I'm not expecting much. First though, I figured I'd better see if the Concerto cart itself actually worked. I'd never tested it, POKEY or not.
21_empty_concerto.JPG

 

I popped it into my 7800 with a fresh SD card (since I can't find my old ones), fired up a 7800 test binary, and presto! No POKEY! Because I hadn't installed it yet. But hey - the cart works. I tried a few other binaries just to make sure, including Ballblazer (which was deafeningly, and unsurprisingly, silent).
22_test_cart_no_pokey.JPG

 

Time to install the Hacky POKEY! Opening the shell, I somehow managed to break off a tiny little alignment pin. Bummer. But that's what screws are for.
23_broken_cart_tab.JPG

 

I gently (or gingerly even) seated the POKEY in the socket, and carefully squeezed it into place:
24_pokey_installed_front.JPG

 

Everything fully seated, and no bent pins! I considered throwing a little JB Weld over the corner to tidy it up, but I kind-of like the look. It has a history to it now. And also, I didn't want to spend the time on it (thirty percent chance of success and such).
25_pokey_installed_back.JPG

 

Before doing anything else, I checked continuity from the chip through the board. Just to make sure that if the chip still worked (thirty percent), that the signal paths were good.
26_continuity_tested.JPG

 

I then reassembled the cart...
27_concerto_assembled.JPG

 

And fired it up!
28_7800_onna_shelf.JPG

 

Would it work? Well... first I had to wade through the Concerto's startup sequence:
29_concerto_reminder.JPG

Looks pretty good for stock RF.

 

Then I loaded the test cart binary...
30_test_cart_menu.JPG

 

And... nothing! Still no POKEY.
31_test_cart_still_no_pokey.JPG

 

Thirty.

Percent.

 

But then I thought, "What if the test binary doesn't see the POKEY because it's in the Concerto?" The Concerto isn't exactly 100% compatible. So, I fired up Ballblazer...
32_ballblazer_title.JPG

 

And was met with some reassuringly jamming tunes! The POKEY worked! Take that, other 70%!
33_ballblazer_gameplay.JPG

You'll just have to pretend this is video. But the music is there.

 

Just to be sure, I fired up Commando:
34_commando_title.JPG

 

And that worked, too! (Again, you'll have to pretend.)
35_commando_gameplay.JPG

So I managed to revive James' mangled POKEY! And now I have a working POKEY for my Concerto cart!

 

Unless he wants it back. :ponder: 

 

That would be awkward. I'm kind-of attached to it now.

 

Anyway...

 

And yes, my 7800's video is a little bit lot on the dark side:
36_7800_color_chart.JPG

 

But my monitor is calibrated properly for NTSC:
37_ntsc_bars.JPG

 

It's hard to get a good picture with my iPhone (refuse to upgrade), but yes, the PLUGE is clearly visible in person:
38_pluge.JPG

Not sure if adding a UAV mod would address the brightness issue, but I'll likely try that at some point.

 

After I experiment practice on John's 7800, that is. You think this POKEY was a mess? Just wait.

 

But that's a story for another time... ;) 

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To be fair to the Concerto, it looks like the 7800 Utility Cart image doesn't have pokey flagged in the header, so Concerto did the right thing by not enabling it.

 

( @Trebor might be a good idea to throw a pokey@4000 header variant of the Utility Cart in the rom pack)

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Great story and great job! I'll PM you my address to send it back...  j/k!!

 

Wow, after I completely mangled it I never thought it would ever sing beautiful POKEY songs again, amazing work!

 

- James

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2 hours ago, RevEng said:

To be fair to the Concerto, it looks like the 7800 Utility Cart image doesn't have pokey flagged in the header, so Concerto did the right thing by not enabling it.

 

( @Trebor might be a good idea to throw a pokey@4000 header variant of the Utility Cart in the rom pack)

Thanks for the info. Adding that variant would be helpful. I kept looking through Trebor's utility collection for something that would just tell me, "Yep. There's a POKEY here."

2 hours ago, ZeroPage Homebrew said:

Great story and great job! I'll PM you my address to send it back...  j/k!!

 

Wow, after I completely mangled it I never thought it would ever sing beautiful POKEY songs again, amazing work!

Thanks! And thanks for sending me the POKEY. That was a pretty long-shot repair, but it was fun to try something different and I'm pleased it worked out (and that the Ballblazer cart didn't die a horrible death in vain ;) ).

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7 hours ago, RevEng said:

To be fair to the Concerto, it looks like the 7800 Utility Cart image doesn't have pokey flagged in the header, so Concerto did the right thing by not enabling it.

 

( @Trebor might be a good idea to throw a pokey@4000 header variant of the Utility Cart in the rom pack)

Done.  Will be present in the next release of the 7800 ProPack.

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