PCB game board repair - Dark Tower 1981 - Ti TL496CP chip does not have 9v out

[ClassicII]

Hey Guys!

First time repair post and was hoping some one would point me in the right direction.

The board game is called Dark Tower and is from 1981. The main tower part is a really neat and is powered by 2 D cell batteries and has lights and sounds.

The problem is it does not power up. I have at least some troubleshooting skills but have about topped out on what else i can check.

This is a link to a site where a guy worked on his. You can see the pictures of what the tower looks like along with pictures of the board. It also looks like he mapped out the circuits.

http://www.haxx0rdezimal.de/teardownfix_vintage_dark_tower.htm


I think i have isolated the issue to the Ti TL496CP chip. Looks like this takes the input of the 2 D batteries at 3.0v and ups the voltage to 9v. When I turn on the game that line only outputs .89 volts.

This is the Datasheet from the TL496CP
http://bg-electronics.de/datenblaetter/Schaltkreise/TL496CP.pdf

On this chip it only uses ports 2, 5,6,7,8

On input 2c i get 3v
On SW i get 3v
On 8 output i get .89v

When I apply 9v to the #8 output the system powers up and works.

I am not sure what I should get at the SW. Also does this mean that the chip is not getting the right switch or ground signal to power up or does this maybe mean that the chip is defective and not putting out the proper 9v ?



Thanks in advance to any one that can help bring this 35 year old game back to life!

 

[(*steve*)]

It may be easier to remove the 3V to 9V circuit and power the device from (say) 6 AA cells in series.

I believe those TL496 chips get instantly destroyed by reverse voltage, and I'm not sure how well they handle overload.

There are cheap boost converters on ebay that can do this more robustly, or you can try to fix the existing device.

If you're going for the fix, can you obtain a TL496? That's the most likely failure unless its something trivial like a wire becoming disconnected.

 

[ClassicII]

It may be easier to remove the 3V to 9V circuit and power the device from (say) 6 AA cells in series.

I believe those TL496 chips get instantly destroyed by reverse voltage, and I'm not sure how well they handle overload.

There are cheap boost converters on ebay that can do this more robustly, or you can try to fix the existing device.

If you're going for the fix, can you obtain a TL496? That's the most likely failure unless its something trivial like a wire becoming disconnected.

Thanks for the info Steve. That really seems like an Interesting solution with the 6 AA as works when I apply 9v.

They do sell the chip from china for cheap but usually takes a month so i may try that route but wanted to check to see if maybe i was missing something first before I ordered one.

But from what you are saying its most likely a chip like this that would fail after all these years instead of other components on the board?

The one thing that I'm trying to understand is the switch or SW part of the chip. Does that turn on and off for some reason or should that chip be putting out 9v at all times?

 

[(*steve*)]

The one thing that I'm trying to understand is the switch or SW part of the chip. Does that turn on and off for some reason or should that chip be putting out 9v at all times?

It all depends on how the circuit is wired up.

You need a schematic of the actual circuit to give a definite answer.

However it is very unlikely that the chip would be powered all the time (which would be required to have 9V present at all times) ad it would drain the batteries for no good reason.

 

[rwburbage]

Hey Guys!

First time repair post and was hoping some one would point me in the right direction.

The board game is called Dark Tower and is from 1981. The main tower part is a really neat and is powered by 2 D cell batteries and has lights and sounds.

The problem is it does not power up. I have at least some troubleshooting skills but have about topped out on what else i can check.

This is a link to a site where a guy worked on his. You can see the pictures of what the tower looks like along with pictures of the board. It also looks like he mapped out the circuits.

http://www.haxx0rdezimal.de/teardownfix_vintage_dark_tower.htm


I think i have isolated the issue to the Ti TL496CP chip. Looks like this takes the input of the 2 D batteries at 3.0v and ups the voltage to 9v. When I turn on the game that line only outputs .89 volts.

This is the Datasheet from the TL496CP
http://bg-electronics.de/datenblaetter/Schaltkreise/TL496CP.pdf

On this chip it only uses ports 2, 5,6,7,8

On input 2c i get 3v
On SW i get 3v
On 8 output i get .89v

When I apply 9v to the #8 output the system powers up and works.

I am not sure what I should get at the SW. Also does this mean that the chip is not getting the right switch or ground signal to power up or does this maybe mean that the chip is defective and not putting out the proper 9v ?



Thanks in advance to any one that can help bring this 35 year old game back to life!

Hello, did you get that Tower back up and running. That was clever in applying 9V right to the processor. Yes, those chips from china are still made and do the job. I've repaired several towers with that chip toasted. One even had a meltdown in the middle. Let me know if I can help and this was posted years ago.