Another Donkey Kong Jr (DKJr) restoration thread

WannaTheater

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After saying I wouldn't be doing another restoration any time soon, fate kicked me in the head. I managed to pick up this Donkey Kong Jr. locally. All electronics, monitor, etc, were initially removed, so basically it was purchased in an unknown condition. As an added bonus, this also came with Donkey Kong (2-board) and Popeye boardsets.

Here is what was known:
1) Monitor had been recapped, but visual inspection showed some wires not connected
2) Some hacked harnesses (trivial)
3) Donkey Kong, Donkey Kong Jr boardsets, and powersupply were apparently working before monitor recap
4) Popeye boardset untested
5) Audio board does not work, and has not been recapped
6) Cabinet solid, but de-laminating. Has back door.
7) Minimal screen burn







 
First order of business- Clean up cables.

Video, power and yoke cables all electrical taped:



Cleaned up using some goo gone, reconnected, and used some harbor freight shrink wrap and heat gun.

 
Next was trying to determine what was wrong with the monitor. Information about the repair process can be found here:
https://forums.arcade-museum.com/showthread.php?t=449944

In summary:
1) HOT had two leads reversed - Corrected
2) Reseated Flyback- Carved out notch in case so it would sit flat.
3) Found a few cracked solder pads/runs - Repaired
4) A solder bridge was identified (@vectorman had this same issue). Repaired.
See the following: https://forums.arcade-museum.com/showthread.php?t=444561
5) The leads to the SCREEN pot were reversed (my bad.... Thanks Again, @paul400). Took a very long time to figure this issue out, but now all is good with the monitor:



 
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Next up was the audio board. Some work with the multimeter, and it was determined that fusable resistor R383 was open... and the transistors were not testing correctly. I purchased a cap/traisistor rebuild kit from Peter at https://www.arcadepartsandrepair.com/.

I also replaced a few other resistors that were cracked/burned, and reflowed all solder joints.
(You can see burn at R380). I believe I replaced R380, R381 and R382.





This corrected the audio amplifier board issues.
 
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Cleaned up power supply. Everything disassembled, wires scrubbed, wood sanded. Thought about painting the top of the power supply gold... and would have if I had the paint sitting around-

Before:


After:
 
Cleaned up the marquee light. Bulb was missing, starter was char-broiled. I purchased a new cord from Home Depot (extension cord), and cut off the female end. Fixture was painted using Rust-Oleum Semi-Gloss White (I taped off the original specification sticker to maintain history...). Connected using butt-connectors and shrink tubing/heat gun. Since this replacement cord is thicker than the original, the strain-relief plug would not fit. So I employed the knot mechanism of strain relief.

Also note, even though the photo shows a 6-ft replacement cord, I actually used a longer one (I think 9 feet, then cut is down to match the original length).





Fixture completed with starter and bulb purchased from Steven at Arcadeshop. Will find out if it works once I get the game put back together.

 
Next up: Cabinet stripping/disassembly

The laminate on one side was basically falling off. Using a drywall knife, both sides were stripped:





This piece of wood was a pain to remove- Stapled to the front black piece (with decal) and stapled/glued to the front bottom of the monitor shelf.



It did some damage to the bottom of the monitor shelf wood, but nothing major. Will need to clean it up.

 
I got lucky in that the coin door panel was able to be removed (no hidden screws). But it would have been much more difficult getting to the bottom screws without this:



Front pieces removed:



With the cabinet being open, I was able to sand, getting rid of the past years of funk on the surface of the wood.
 
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Inside of front panel- sanded (defunked!)

The bottom support on the front panel needed some attention:



The four screw heads basically rusted off, and the the piece of wood was pretty wobbly. Home Depot sells square dowels that are pretty close to the required dimension (in the wood trim section). I removed the old one, cut a new one, and wood glued and screwed it down. Will need to pre-drill some holes which will be used to screw DOWN into the floor of the cabinet- (The original was stapled).
 
Taking a step back... before I disassembled the cabinet, Donkey Kong Jr sound was fine. But the Donkey Kong boardset only had SOME sounds (boom boom, sneakers squeaking, etc). This is where a logic probe comes in handy:



While I've heard this problem is sometimes corrected by replacing VR2 (10K pot) on the CPU board, mine looked like it had already been replaced. With the logic probe, you can trace the signal back to find where it dies. With the game off, I just connect the red and black leads across one of the capacitors holding up 5V near the top of the CPU board (red on positive, black on negative). Then power the game on, with a game started, touch the probe to the pins I am interested in- The logic probe will not beep, it will "squelch" and sound like the Donkey Kong sounds if the analog signal is present. If not, the Logic Probe will either sound a high pitch or low pitch depending on if the pin is stuck high or low.

I checked the following Op Amp pins, and found nothing:
MB3614 (Location 7K) pin 8 (2nd stage op amp output)
MB3614 (Location 7K) pin 13 (1st stage op amp input)

Then I checked the D/A converter (Location 8k):
Nothing at Pin 4 (output).
I checked some of the input data lines (Pins 5-12) - Nothing

So now I am thinking sound processor (7H). I checked the input clock of sound processor (Pin 2), and nothing was there. So I INCORRECTLY thought the crystal X1 was bad. I replaced it with a known good crystal. No change. I vaguely remember you really can't check a crystal like I did... I digress.

So I swapped the sound processor from my working DK Jr CPU board, and bingo, the missing digital sounds are now present. I received the required replacement today from Mike's Arcade.

Awesome tool for getting into tight places to pull ICs without mangling pins:



And here is the culprit:

 
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Cleaned the following up with a razor blade and some Goo Gone, then lightly sanded. I tried to paint it using Rust-Oleum 2X (with the primer included), but didn't like it. It is like that paint dimples on the melamine-like coating. The same happened on the topside of the control panel. Instead I used standard Rust-Oleum Semi-Gloss (the stuff that takes a long time to dry).

Before:


After, with decal from Arcadeshop:




I also had some Rust-Oleum Metallic on hand. Great for blinging out metal parts.... even inside a cabinet the nobody will ever see.



 
To build a new base, I followed this guide pretty closely:
https://www.youtube.com/watch?v=O5sYknlL3-s

I did rip the wood down a bit to make the width match what was already on the cabinet.
Fortunately I already had the corner clamps. Corners are held together with glue. I used SPAX screws from Home Depot (#6 I think) - pre-drilled the holes to prevent the blocks from splitting. The top 4 blocks were also glued in addition to the screws.

Original (Was previously spray painted white):





Spray painted with a few coats of the following:
(I also used some gray sandable build-up primer to try to get rid of some the wood grain)




Looks good enough, even though you can still see the wood grain. I won't be installing this until I complete laminating the cabinet sides. It has been brutally hot in Florida lately- Laminating outside is not going to be fun. And Bondo sets up in a matter of minutes.
 
Purchased laminate from John Alvelo at Top Cabinet Hardware in Mirimar, FL. Purchased two sheets of Fresh Papaya Gloss- shipped to my house. Ordered on a Friday, received on the following Friday.



I cut the pieces (rough dimensions) on a table saw. Last year I put a Diablo blade on it to fine cut cabinetry trim- the blade is awesome. It cut through the laminate without chipping at all. Even though I taped the cut lines, I really did not need to. The only issue was the material kept creeping under the fence, so I had to keep an eye on that.
 
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Laminating front piece (coin door):

All rough edges and chips were Bondo'ed. The front was sanded with 60 grit on random orbital sander.



After gluing down the laminate, I then used a router laminate trim bit to cut away the edges (which were overhanging about an inch. I had to look up trim direction on youtube- Routing the OUTSIDE you go COUNTER CLOCKWISE. A straight file was then used to clean up any sharp stuff. For the inside, I drilled a couple of holes near one of the inside corners to fit the router bit through. On the INSIDE, you run your router CLOCKWISE. I then drilled out the bolt holes (from back to front)

My method of drilling:
1) PRACTICE ON SCRAP to make sure drill bit doesn't catch and mangle laminate
2) I drilled through the back, with the face of the material on a piece of 2x4 that would act to sandwich the laminate between the substrate and the 2x4
3) Use an exacto knofe to widen holes and de-burr

Final product (that is a shadow on the bottom):

 
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Laminating the speaker panel assembly:

I tried to do this without taking it apart, and glued the laminate on both faces. I left the original laminate on the inside alone:



I was able to trim the piece shown on top (really the front speaker panel) with the router trim bit. But the small rectangle laminated piece (perpendicular to the speaker panel) I could not trim with the big router. They make specialty laminate trimmers (small routers), but I didn't want to purchase one. So I resorted to using metal cutters, a sharp utility knife, a file, and a lot of time and patience.





To do the speaker grooves, I drilled small holes in each slot (again, from back to front). I then widened the holes into squares with an exacto knife so the router bit would fit through. I then routed each groove in a clockwise direction (lined the router up first, through the square hole, THEN turned the router ON. Special thanks to @seanengadet, whose Donkey Kong Barn Find restoration thread pointed me to a very small router trim bit that would work. I purchased mine from Amazon (came from ToolsToday). All edges were cleaned up with a straight file.





Once routed, I taped things off and sprayed the edges and inside with semi-gloss black. The black did bleed onto the other side (even under the tape), so in several places (especially the speaker grooves) I had to use my fingernail to get the paint off the laminate. I am really glad it came off...





Lesson learned: In prepping the surface for the small laminate piece, there was some glue that holds this piece to the front speaker panel. I did not do a good job of cleaning it out. As a result, the inside edge of the laminate is not as solidly glued down as I would have liked. Little bumps on the surface can make bigger bumps on non-flexible laminate.
... nobody will ever see it, as it is on the underside of the speaker panel.... but I know its there :)
 
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Restoration of the control panel:

The original control panel had the typical discolored blue buttons, complete with cigarette burns. Add in some faded reds, liquid spills, yellowed/broken T-molding, and various dents and dings.



Joystick base was disassembled and soaked in rust remover. Joystick yellowed plastic ring cut off and replaced with a small piece of Home Depot tubing. Ball top wet sanded and buffed (Novus'ed) using the "Drill method." Wire harness cleaned. Used a little synthethic grease on the captive bearing. Replaced spring, which was purchased from Mike's Arcade.



Cleaned-up version (the whitish look on the right side is room lighting and my poor iPhone camera skills):
1) Bondo'ed the visible dings
2) Rust-Oleum semi-gloss black painted (original paint version on top, fast drying 2X version on bottom)
3) New buttons, clear plastic dust guard disc and T-molding from Mike's Arcade
4) New Control Panel Overlay from Arcadeshop
5) Metal parts/hardware (all) went through a tumbler, and the 8 bolts cleaned up nice.





As mentioned previously, I really like the Rust-Oleum metal paint. Bling Bling :)

 
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Preparing cabinet for laminate:

Cabinet was sanded. There were several separating layers of plywood, which were cut away and replaced with Bondo. The corners were Bondo'ed etc. Edges were spayed black.







 
Laminating:

I used Wilsonart 600 adhesive, rolled on with a 9" adhesive roller from Home Depot. Dowels (about 5) were used to position the laminate appropriately, then pressed down with J-roller, successively removing one dowel at a time. Be careful- Once this adhesive grabs hold, it will rip a layer of plywood before the glue will separate!



Edges trimmed with router.



Ragged edge after routing which needs to be knocked down with straight file. I am leaving protective plastic on until complete.

 
The bottom was sanded (funk removal) and new base installed- Used 2" Spax and wood glue.



Installed wheels, and completed painting the inside of the cabinet:



 
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