(Topic ID: 210346)

Doctor Who Intermittent Error??


By tom_baker

1 year ago



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  • 30 posts
  • 10 Pinsiders participating
  • Latest reply 1 year ago by tom_baker
  • Topic is favorited by 1 Pinsider

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Escape drivers (resized).jpg
Escape matrix (resized).jpg

#1 1 year ago

I recently got a Doctor Who machine in generally fine shape, but there is a problem that is driving me crazy. Most of the time, it doesn't successfully begin the W-H-O sequence. All lamps and switches are working properly; when the ball goes up the right ramp (W is lit), the machine knows that the ball has entered there, and the HANG ON lights up...but not the "H" (though the H lamp will light as part of various display sequences). And when the ball is sent up that chute, the switch identifies that the Hangon had been made, but the W-H-O does not continue and the O (top ramp) light. However, every now and then, it will start work fine for a while, and then stop. I looked for any poorly seated jumpers or chips, and haven't been able to find any. I'm not an electrical engineer, and don't know how to identify any errors in the solid state components or their programming! This unit came from Europe and was converted back to US, if that is at all relevant. I'd appreciate any suggestions. Thanks!

#2 1 year ago

Step one: When you say all the lamps and switches are working properly, did you test them in test mode?

#3 1 year ago
Quoted from CadillacMusic:

Step one: When you say all the lamps and switches are working properly, did you test them in test mode?

With a ball, not your finger?

#4 1 year ago

Yup, tested all switches with a ball, tossing it through the ramps where I couldn't reach. (Actually, not all lamps are working; the whole ESCAPE bank is off, but I figured that is something different and will get to that next.)

#5 1 year ago

If all the switches test ok, I'd look at the touch points on the power driver board. Clean power on the optos is kinda important. But check 'em all to be sure.

I was not expecting all the switches to work... my thought was the compensation code. But if all the switches register.
You did the Test14 switches too... yes?
faz

#6 1 year ago

Did you try a factory reset to be sure it's not some obscure difficulty setting?

#7 1 year ago

Okay, so I pulled out and reseated the jumpers on the power driver board, and checked all ICs looking well seated and it worked for a while. But then it stopped working again. Yes, I did test14 (the miniplayfield, right?). And did a factory reset too. It doesnt seem to be obviously associated with temperature (my other idea). So it recognizes that the W-H-O cycle has started when the ball goes up the right ramp, but the H lamp (which works) does not come on. Seems like it's something wrong with its brain...

#8 1 year ago
Quoted from tom_baker:

Okay, so I pulled out and reseated the jumpers on the power driver board, and checked all ICs looking well seated and it worked for a while. But then it stopped working again. Yes, I did test14 (the miniplayfield, right?). And did a factory reset too. It doesnt seem to be obviously associated with temperature (my other idea). So it recognizes that the W-H-O cycle has started when the ball goes up the right ramp, but the H lamp (which works) does not come on. Seems like it's something wrong with its brain...

If the PDB is getting too hot or the voltage regulator is not keeping things regulated, consider replacing it with a P5US

#9 1 year ago

In case no one else has asked yet are there any signs of corrosion on the CPU board below the battery holder? That is very common and can affect the chips for the switch matrix. There could also be remnants of the corrosion causing problems on the board or in the wiring connectors in that area.

#10 1 year ago

hmmmm... the PDB does not seem to be very hot; I am not sure about how to check the voltage regulator. No corrosion on the CPU board. But I didn't mention that there is a buzzy squeal, rather quiet, that is definitely associated with the display screen (it changes with the screen). It sounds like a ground hum that screens often have. It is plugged into a three prong outlet, and at one point, an electrician checked that the outlets were properly grounded, though the house is super old....

#11 1 year ago
Quoted from tom_baker:

hmmmm... the PDB does not seem to be very hot; I am not sure about how to check the voltage regulator. No corrosion on the CPU board. But I didn't mention that there is a buzzy squeal, rather quiet, that is definitely associated with the display screen (it changes with the screen). It sounds like a ground hum that screens often have. It is plugged into a three prong outlet, and at one point, an electrician checked that the outlets were properly grounded, though the house is super old....

I meant that if the voltage is either too high or too low. You can test on the 5v test point. With a multimeter, red on the test point, black on ground braid. The voltage needs to be about 5v, even 4.8 can be too low

#12 1 year ago

I find it suspicious that W lights up, but not H or O. H and O are flashers, not regular 44 lamps like W. Do these flashers work in test mode?

#13 1 year ago

Okay, tried that, 4.97 on the PDB test point, 12V Test point also checked out...and yes, the flashers do work in test mode....

#14 1 year ago
Quoted from tom_baker:

Okay, tried that, 4.97 on the PDB test point, 12V Test point also checked out...and yes, the flashers do work in test mode....

OK. When you tested the switches, did you check switch 36 and 37? Both need to be working to register the W shot.

#15 1 year ago

I think that was it! Thanks so much for pushing on that, aroden. I was too confident of the results of a single test. The housing for switch 37 is a bit loose. Usually when I test it, it works, but when the ball comes around the bend, if the housing has shifted, it can scoot past the wire. Bending the wire seems to have fixed it for now. But it doesnt seem possible to tighten the housing -- those screws don't seem to go into anything fixed.

Assuming that was indeed the problem, let me ask about the other major puzzle: all the ESCAPE lamps don't work, although the bulbs look fine; I replaced one with a new one to see if it made a difference. It doesn't. They don't go on in Test Mode, nor in General Illumination. Is there something obvious I can check? The ESCAPE switches all do work....

Thanks again!

#16 1 year ago

Are the lamps all in the same row or column on the lamp matrix? Check for a broken wire at the non-working lamp closest to the connector in the backbox.

#17 1 year ago

Did you check the connectors in the Backbox? J137-1 is common for all the ESCAPE lites. J133 pins 1,2,4,5,6,7 are for the each of the letters. Other than a loose wire or broken etch at the connector at the bulb board. Take the bulb board out and carefully check the connector on the board. Wiggle it and ohm it out.

Escape matrix (resized).jpg

Escape drivers (resized).jpg

#18 1 year ago

escape lamps are all on lamp board, I'd check for broken solder joints (or just reflow solder) on that board first.

#19 1 year ago
Quoted from wdennie:

I'd check for broken solder joints

That's most likely the cause.

#20 1 year ago

Okay, maybe I'm missing something -- I took out the board with the bulbs, took out the bulbs, and tested all the solder lines for continuity, and all had it. I don't know if there is anything else I should look for there? As for the connectors on the backbox, I did look, everything seemed fine. But also, lamps 17 and 18 (left drain and return) work, so that means it isn't J137, right? Can you let me know what it means to "ohm it out"? I'm sorta new at this....
thanks!

#21 1 year ago

Testing for continuity is "ohming it out".

-1
#22 1 year ago
Quoted from YeOldPinPlayer:

Testing for continuity is "ohming it out".

No, it's not. Measuring ohms is checking resistance, not continuity.

#23 1 year ago

Basically the same thing. Zero ohms or close to it is showing there’s a good connection or continuity. So none of the bulbs are working? Did you ever see them work?

#24 1 year ago
Quoted from YeOldPinPlayer:

Testing for continuity is "ohming it out".

Quoted from dsuperbee:

No, it's not. Measuring ohms is checking resistance, not continuity.

Zero resistance IS continuity.

#25 1 year ago
Quoted from YeOldPinPlayer:

Zero resistance IS continuity.

Yeah, I know. But nobody calls checking for continuity ohming it out. They call it checking for continuity.

#26 1 year ago

With the lamp board connected, wiggle the connector up and down and side to side. Do the lamps work while doing this? If so, it's likely a solder joint issue. Just checking for continuity doesn't necessarily eliminate the issue as the board moves and flexes a lot when connected, potentially disrupting the joint.

#27 1 year ago
Quoted from dsuperbee:

But nobody calls checking for continuity ohming it out.

Sorry, i’ve Been calling it that for at least 40 yrs. Just habit I guess. Call it what you like. Continuity is certainly a better description. Also, what @arorlden said is exactly what you should do. I was assuming that you already tried that. You could do the same with the connectors in the back box. If it’s not a connection problem then you’re looking at possibly a component problem. If Q98 is bad or something with that circuit. You do have a copy of the manual right?

#28 1 year ago

Ok, arolden, you are two for two. Pressing gently on the middle of the board causes the connection to be made. I tried just loosening the attaching screws in case they were bending the board down, but that didn't fix things. So I guess I just try to remove and resolder the connector? Thanks!

#29 1 year ago
Quoted from tom_baker:

Ok, arolden, you are two for two. Pressing gently on the middle of the board causes the connection to be made. I tried just loosening the attaching screws in case they were bending the board down, but that didn't fix things. So I guess I just try to remove and resolder the connector? Thanks!

Don't worry about the connector. Reflow solder around the header pins on the lamp board. That should do the trick.

#30 1 year ago

Great! Will do. Thanks again.

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