Ramp stopped working on CFTBL .. Fixed !

[goodolddays]

Gday all.
The ramp that moves down during multiball has stopped working on my Creature.  

It moves down but not back up.
Ran up/down ramp test with playfield up and looks like the coil to move it up is not being pulsed. (solenoid 23 ?) Doesn't look like a physical problem cause I reflowed the solder on both the lugs , measured the coil at around 20 ohms (so not a broken winding ?) , checked the switch operation with meter and its OK , the diode connected to the switch also tests OK . Can manually operate the armature of the coil and the ramp moves up OK.

I guess the driver board is not sending an earth to the coil due to a faulty transistor ? I assume there is a seperate transistor to drive each coil ? . Is it easy to find which transistor is related to this solenoid or do I need to check them all on the driver board . I haven't yet checked for continuity between the coil lug and the plug (J206 pin 7 from memory) on the driver board that sends the earth to the coil .
The 50V side should be fine as it is daisy chained from the 'down coil' and checked that connection with the meter fine.

Any other suggestions ?? Anyone else with a Creature had this fault before ?

Such a shame as this game has been getting played a lot by the whole family  since I got it  

[goodolddays]

Just after I posted I noticed the Solenoid/Flasher table in the manual and see that driver transistor for this solenoid is Q34  .

So I spose next step is find and test Q34 on driver board right ?

[goodolddays]

Also, manual mentions a 'tieback diode' , connected via J126 pin 12. Where would this diode be and what is it for ?

[swinks]

Hi mate, I don't have any experience in that one but will watch and learn. Good Luck.

[goodolddays]

Hmm .. well
a) I have checked and have continuity between the earth lug on the coil and pin 7 on J126.
b) I tested Q34 and it seems OK ?? Base reads .737V , collector is a short , emitter reads .471V . I compared this to the adjacent transistor Q42 ?? same type and similar readings .
I tested with DMM set to diode function, black lead on metal tab , red lead on a leg

What do I do next ??

To prove its not the Q34 could I swap the earth wires between the up and down coils ?? (ie in  ramp test , ramp would go up when it should go down and vice versa ) ?? If I can safely do this , and ramp does not go down then I would replace Q34

[Retropin]

Not too savvy with later machines, but cant you do the simple trick of touching the transistor tab with a wire run to ground?...  you should see if the coil then tries to pull the ramp up. If it dies then its a signal fault TO the transistor

[goodolddays]

Not too savvy with later machines, but cant you do the simple trick of touching the transistor tab with a wire run to ground?...  you should see if the coil then tries to pull the ramp up. If it dies then its a signal fault TO the transistor

Good idea Gav .. didn't think of that .. will give it a try .

Cheers
Dave

[goodolddays]

OK, grounding tab of transistor (Q34) with game on and test button pressed once (per Clay's guide) coil fires , so must be one of either Q34 ,  the pre driver transistor (Q33 the game tells me by running solenoid test on S23 and pressing start button) or the  related 74LS374 .

Any which way looks like I have to pull the driver board out and guess I will replace both the TIP102 (Q34) and a 2N5401 (Q33) .

Be good if I can fix this myself

[Retropin]

If coil fires by grounding the tab then that transistor is OK.. could be pre driver or 7XXXX chip, but Q34 is OK

[goodolddays]

Read in Clays WPC repair guide today how he had seen this problem (one coil not firing) fixed by reseating the ribbon cable between CPU board and Power Driver board .

With nothing to lose I gave that a try tonight (reseated both ends) .. powered up and no lights and an error saying Slam Tilt switch stuck on .

Reseated both ends again and now all good, includng the ramp up coil   

Pity I already ordered the parts today , oh well, they'll probably come in handy down the track sometime. 

[pinnies4me]

It is amazing how many problems can be traced back to connectors - having worked on lots of Gottliebs it's became the first thing I do now, re-seat them (and then repin them!) Great to see you got it solved.

[Steevsee]

Nice Work!