D&D Computer Labyrinth

[SiberianSpForces]

Used to have one that ended up disappearing. Snagged a non working one off eBay and figured it would be a quick solder job. Not the case, as everything on the board and membrane looks fine. I can't find any type of schematic or technical info for it. I took the multi meter to it and there's 4 parts that I'm wondering about. There's 2 resistors behind the power jack that reads 001, resistor in front of these ribbon reads 004 and the cap next to the speaker just has a 1 that's towards the left side of the display. Any assistance is always appreciated.

[82-T/A]

For the rest of us that have never seen one:

 

 

 

 

Good luck! Hope you get it fixed! It looks awesome!

[imstarryeyed]

I have one of those, mine has very quite but still noticeable sound.

 

What is yours doing exactly? Are you able to power it up? Do you know if it is powered?

 

Have you checked it with your multimeter to see if and where you are losing power.

 

In my case I am guessing my caps are out and that low sound is the result.

 

I would think that power maybe some bad joints on the power plug?

[SiberianSpForces]

The cap right next to the speaker isn't giving a reading. The display just shows 1 on the left hand side. Then the 2 resistors behind the power input are reading 001, 001, and the one in front of the ribbon is 004. All the joints look good and nothing seems loose. I'm not sure how to test the speaker exactly.

[Tanooki]

Maybe I'm overcomplicating it, but other than the TI chip with the game on it, could all the other parts soldered to the board basically be replaced with modern off the shelf equivalents? I mean unless you're doing some weird period crazy has to be right thing, couldn't replacing the parts potentially solve the problem? At the least it could narrow down what is not causing the problem. From there then you could get into trace checking and so on.

[SiberianSpForces]

Yeah, that's something I could try to do. I can google the modern equivalent to the original components and go from there.

[imstarryeyed]

Check your power:

 

1) check battery tabs at battery compartment.. sometimes corrosion causes batteries to not work.

 

2) once you are convinced that the battery holder's internal tabs are putting out power, follow the power wires to the next component, I imagine the switch and check it in both positions on and off.

3) follow the switch to the next component and make sure power is going there.. I am sure there will be a place where power is not going and I would think that would be your suspect.

 

My guess is if you have battery corrosion that will be the problem even if it looks "good" in there.. if that is not it and the switch then I can imagine those 2 transistors one or both are the culprit, they are designed most likely as voltage switches to the unit and chips.. Transistors often go out.

 

I bet the resistors are fine.. the caps might need to be changed but I say transistors first.

 

If I had the time I would open mine up and figure out the schematic but I am doing a giant pack for a move soon so everything is boxed up.

 

Can you take a good picture of the front of that board where we can see the traces?

 

In any case I wish you good luck..

[SiberianSpForces]

Yeah, I can post them later tonight. As for testing it with a battery in, do I leave the meter on the max OHMs setting?

[dj_convoy]

The missus got me one of these a couple of years back. It's a pretty fun little gadget. Best of luck restoring it.

[Tanooki]

I had one back in the 80s I got at some garage sale. I only remember it because it was very fun to play with, and was the same sale I got my first electronic handheld too, one of those blue Hockey games from Mattel. It was a really smart and fun game, never had seen what was basically a board game before that interactive and could be played by oneself too. I've been considering for awhile picking up one again the last few years, but never went through with it.

[SiberianSpForces]

Here's a couple close ups. I tested the transistors and got numbers from both. I also got numbers from that cap by the speaker by swapping where I put the + and - from the meter. I also tested the speaker with a 9v and it pops when I test the contacts on the speaker and board.

[Reaperman]

Silly question, but have you been a little rough with the power switch yet?

Power switches often get a bit dirty inside, and after 30 years, they can develop their own 'personality.'

Applying a moderate bit of force straight back while sliding the switch from side to side may help clean it up enough to start getting some sound.

 

Those power sockets also have a mechanical battery cutoff in them that can develop a 'personality' too, if any of its previous owners were silly enough to try using it, or even worse, stored it with a power adapter plugged into it.

 

I've really got to give mine a go--I really like this game in short bursts of maybe 2-3 games at a sitting. On a slightly related note, about a year ago I bought a beautiful vintage calculator with a the mindset of 'it's too simple to really fail', and at the and of the day, I reached the conclusion that its similar-vintage TI-calculator-on-a-chip had given up on the will to live.

Edited September 6, 2018 by Reaperman

[phoenixdownita]

Well, when powered up does the microcontroller get warm at all?

[imstarryeyed]

Okay lets take a look at this..

 

I do not mean to talk down at all in this posting, I am writing this for the community of some of the super nice folks we have here that are afraid to test electronics.. I am trying to communicate such friendly steps that I hope encourages others to jump in and not be afraid. Please understand that I am not trying to treat you as a person who does not understand testing..

 

I hope this helps..

 

I recommend :

 

a multi meter that has a continuity test that beeps

a can of spray contact cleaner (electronics store, this is a tool every retro gamer should have who work on anything with contacts and wires)

 

 

1) get your meter and put it on beep mode or the mode that makes the meter beep when the probes are touched, also known as continuity test.

2) Make sure your meter is beeping by touching the probe tips together.

3) Find the black wire and look at the tab it is soldered to on the battery compartment... beep the wire from there to the other end of the black wire.. it should beep

4) Do the same with the red wire.. once it beeps, keep following those wires until they become traces..

5) Keep beeping from one point you just tested to the next junction on the circuit board.. once you hit a component like a resistor or cap you will need to test those..

 

Put batteries in the battery holder at this point...

 

6) Put your meter on DC voltage and / or something like 20 volts or something in the neighborhood of how much voltage there is in your batteries. If your games takes 2 batteries then you are at 3 volts, 4 batteries gives you 6 volts, 6 batteries is 9 volts.. I forgot how many batteries this thing uses.. but moral here is just put your DC voltage at something a little bit higher in voltage than what you have..

7) Retest the red battery tab with the red probe and the black tab with the black probe, are you getting clean voltage to the tune of how many batteries you have? It should..

8 ) If you are not getting voltage then your battery holder is dirty, clean that up by cleaning it with baking soda and some water to make it a watery paste, that will neutralize battery acid.. let it sit there for a few minutes and then clean it out with some water and alcohol.

9) Continue this testing of voltage to see if you are losing voltage along the way by parking the black probe on the black battery tab and only testing with the red probe going from one junction to the next.

 

Once you get to a place that cannot go any further than look into the idea that power may be dying there.. suspect that component.

 

To test resistors

 

1) remove power batteries..

2) put your meter on Resistance or Ohms that horseshoe looking thing is it..

3) Put both probes on the resistor , one on each side and touch them and wiggle them until you get a reading.. it should be a real reading of a number..

4) Look up that resistor value and compare it to what you have.. read those color bands on it and then use a resistor calculator like

 

https://www.digikey.com/en/resources/conversion-calculators/conversion-calculator-resistor-color-code-4-band

 

5) Your resistor should be within like 10 - 20 % of the number you calculated, if it is within that neighborhood you are probably fine, jump to the next resistor and repeat.. most likely they will all be fine, but if you get one is super weird or 0 then that one may be dead...

 

6) Caps should be changed and don't bother trying to test them, it is a red herring, just change those at the "last resort"

7) Transistors need to be tested very special.. look up how to test a transistor as it is too much to add here.. read your transistor and look it up and test the legs in the order how the instructions say..

 

Test that switch by putting the probes on beeper and make sure its working.. get your spray contact cleaner and spray the heck the inside of that switch and switch it back and forth at least 10 or 20 times you can drench that switch in it and it wont hurt it and it dries super fast. Be careful however that it can stain some plastic , but it wont hurt you if you get some on your hands. I recommend safety glasses as switches tend to splash back cleaner and you don't want to get it in your eyes. This is very safe but use common sense... Remember .... Beware means Be Aware .. Not Be Afraid

 

 

I honestly think you will be able to find your problem with these ideas..

 

Good luck with it I hope this helps anyone who wants to do very basic troubleshooting on electronics..

Edited September 6, 2018 by imstarryeyed

[SiberianSpForces]

I sprayed some Deoxit into the switch and slid it back and forth a few times. The battery it uses is a 9v and it's just the clip the battery connects to. I'll see if my meter can do the beeps and check the board out with that.

[Tanooki]

For fun, seems it's popular in their community but someone made a flash version of this very game, have to have an account annoyingly to download it - https://boardgamegeek.com/filepage/65416/flash-computer-labyrinth

[SiberianSpForces]

I DC tested the bugger and 3 of the resistors are reading 0, along with the speaker. I'm not too sure right now if the speaker reading is important.

[imstarryeyed]

I see voltages going through the board.

 

I say check the diode, that black part with the 6.08 voltage.

 

Pull out the batteries and put your meter on Diode mode.. and check it both ways with the red and black probes on each side.. You should get voltage on one direction but when you switch the probes you should get OL or overload.. If you do then that is a good Diode.

 

Those caps should be changed but only at the end.. if they show signs of puffyness or leaking then they need to be changed immediately but from this angle they look ok.

 

Those 0 resistors should be retested as 0 is very odd, if they continue to test out at 0 then they may be bad.

 

The transistors are the things that I think may be bad here.. Just make sure you are looking how to test them correctly.. You can google that..

 

 

Good luck again

[SiberianSpForces]

Checked the diode, one direction gets the overload display, then the other direction it gives a voltage that starts to drop off. The 0 resistors still come up as 0 when tested. The caps all look great, no puffiness or leakage, then I tested the transistors with the diode setting.

 

I'm not precisely sure which end is E and C on these ;

1st transistor

+ on base/- on E = 729

+ on base/- on C = 731

- on base/+ on E = 772

- on base/+ on C = 1/OL

 

2nd transistor

+ on base/- on E = 731

+ on base/- on C = 1/OL

- on base/+ on E = 751

- on base/+ on C = 770

Edited September 7, 2018 by SiberianSpForces

[imstarryeyed]

Ok Transistors are funny little guys as they can read things and still not be healthy. Look up the transistors and see if you can download a spec sheet on those transistors.

 

Given everything you have found, if you do not wish to dig in a try to troubleshoot those transistors here is my take..

 

If it was my unit, I would change out those resistors and transistors.. There are not too many to change and it is my feeling that your problem may lie there.

 

One last thing is I would recommend before you do anything is to check the voltage on that chip. Look up the chip M34012-N2 and find where the GND or ground is and the VCC or power. If that chip is not getting any power then that would be a problem.

 

Good news is that it looks like that chip is very get-able this day and age.

 

I would say you are well on your way.

 

Good luck

[SiberianSpForces]

Cool beans! I found a text file with some technical info for the D&D game. With the black probe on pin 4 and red on pin 20 I got 6.03, then with red on pin 20, black on the battery clip ground solder joint; 6.02. Hopefully in the morning I can run to the local electronic shop and snag the resistors and transistors.

Edited September 8, 2018 by SiberianSpForces

[SiberianSpForces]

I did replace the 2 transistors and the 3 0 reading resistors. The 3 still reads 0, but one of the 2, behind the power input(closest to the ribbon), will read 4.## after three or so minutes after powering the board up. I might look into a new speaker? I don't know a for sure way to test s speaker this small.

[SiberianSpForces]

So, I took a look at the traces the 3 resistors are on and see they go back to the M34012. One is on pins 4(VDD - Battery) and 9(INIT - resistor to VDD), the resistor that's between the ribbon and the M34012. Then one side of the other 2 are on the same trace/path, which goes to pin 3(R10 - Speaker). Could it be a bum speaker, or something on the chip that's not sending a signal to it?