Data east lw3 help

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I have a couple of components that went bad when I hooked up a new coil in my lethal weapon 3. The burnt resistor is located at r77 by connector cn11. I know the transistor is a tip122 and I think the pre driver at q43 is a 2n4401. It is marked 2sn4401. I'm just not sure what resistor at r77 to order...... Also, is there a possibility that anything else has went bad?

I swear I have everything hooked up correctly and the diode is placed correctly but it fried the components like the diode was hooked up backwards. Does it matter how a coil is hooked up?
 

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The old coil seemed to be weak... I ordered a ton of parts and figured I would replace that too. It was fully operational before I messed with it
 
It was just the coil for one of the kick outs. It does kinda suck, but I'm waiting for a new dmd. It has also givin me the time to install new rubbers and do a thorough cleaning. I went ahead and ordered the correct parts from Great Plains Electronics..... Hopefully nothing else went bad when I zapped it...

Also welcome to the forum, Mojozone..... I see you're also in Iowa, are you into pins, vids or both?
 
It was just the coil for one of the kick outs. It does kinda suck, but I'm waiting for a new dmd. It has also givin me the time to install new rubbers and do a thorough cleaning. I went ahead and ordered the correct parts from Great Plains Electronics..... Hopefully nothing else went bad when I zapped it...

Also welcome to the forum, Mojozone..... I see you're also in Iowa, are you into pins, vids or both?

Thanks man, I am into mostly pins. Child of the 80s arcades. Good luck with your LW3 cool game, one i want to get some day.
 
I finally got around to installing the tip122, 2n4401, and resistor and I'm at a loss.... When I power on the game the left saucer coil stays locked on until I start a game. The coil is released but a flasher lights up and stays lit. The tip122 also gets extremely hot. I'm assuming that this flasher is also powered by the same transistor that I just replaced. The tip36c transistors on the ppb all check out fine so I didn't replace any of those...

I tried unplugging the connector on the mpu that is associated with this coil and it does not activate which tells me that it is not a wiring issue...

I'm hoping someone can point me in the right direction... I've heard to try replacing the pia chips ... Is there a way to test these to see If they are bad? I only have access to a dmd.
 
Your issue lies further up the chain from that specific drive transistor. Do you have the schematics for LW3?

You can test some of those 7XXX TTL chips w/ a meter. This IS not 100% accurate though; I have found some from this method though.

To paraphrase another user on here:
TTLs are easy. Set your DMM on diode test. Put the red lead on
Vss, and use black to check every pin except Vdd. Every pin will should
show a voltage drop of .4 - .9 volts. Shorts definitely mean bad chip,
open means suspect (not all TTL have all pins connected).

Many times can be tested in circuit.
 
In a pinch, yeah thisll do it. A logic probe would be a good way to test it if anyone local has one, or you want to invest $15-$20 on one. Also, try and see if going into diagnostic mode releases the coil. Just double check the playfield status and ensure it does not see the switch that normally drives that coil on (SW40).

On power up, are there any flashes on the PIA led on the mpu?

youll want to look through this as we go :

http://mirror2.ipdb.org/files/1433/Data_East_1992_Lethal_Weapon_3_Manual.pdf
 
I do have a manual that I can look at but I'm not to hot at reading schematics.

I did check the 4 dm7408n chips and one chip read a little off compared to the others. One pin read about .900, but no shorts.

The three LEDs light up as they should when I boot the game.

I was looking a junk pcbs last night and I have some dm7407n chips..... I doubt these are compatible.... Wishful thinking so I don't have to order parts.
 
I do have a manual that I can look at but I'm not to hot at reading schematics.

I did check the 4 dm7408n chips and one chip read a little off compared to the others. One pin read about .900, but no shorts.

The three LEDs light up as they should when I boot the game.

I was looking a junk pcbs last night and I have some dm7407n chips..... I doubt these are compatible.... Wishful thinking so I don't have to order parts.
What pin number reads the oddball value? if your not sure of the number, take a photo of it and circle it in paint or something. When the game is on, you post the black lead of your dmm on ground, and compare the bottom side of the ic to the one next to it with the dmm set to vdc. With no game going (or better, in diagnostic mode) the inputs and outputs on each should match. If the inputs (top side) on each match, and the outputs (bottom side) dont, then theres the problem.
 
I just retread through the thread and realized that .9 is normal. I just had .4 and .6 drilled in my head from testing transistors. Unfortunately I already removed the chip. I should have sockets and chips here tomorrow.

I just received a working board and plugged it in. It worked 100percent, so now I know it definitively is my mpu. I'm planning on replacing the tip122 with a tip102. I will also replace the 4401. The original 4401 has s2n 4401 on it and my replacements only have 2n4401 written on them..... Could this be a problem?
 
Unlikely, the s2n4401 afaik is just a mfg marking in front of the 2n4401. Shouldnt have a problem replacing the 5a tip122 w/ the 8a 102.

The test on the ic with a dmm is only a partial check. It may still be bad, so that isnt in vain. Also check the driver right before that ic.
 
Update.... I socketed the 4 7408s and replaced a sketchy tip122 with a tip102. I fired it up and everything works as it should. Ultimately I believe that it was a flakey 7408. I really appreciate all of the input from you guys.... Hopefully my troubles will help someone else later on....
 
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