two q*bert restoration questions

elfyhead

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two questions on a q*bert restoration:

1 - i can't seem to get the high score fix to work. i'm using one of the Arcade Shop replacement power supplies, and have replaced C25 with a 470 uF, and have put in 2 STMicroelectronics m48z02 zeropower RAMs and taken out the diode at D2 and replaced it with a jumper. still no love. i'm sure the power supply is OK, as i've got another CPU board that works fine (saves high scores even with no fixes at all - all original parts!). the power on pin 40 of the 8088 is at 5.05 V, so that's not the problem. where should i check next?

2 - the knocker isn't working (i know, big surprise!). when i bought the beast, it had a burned out 2N6044 at Q2, so i figured that was the problem, but when i replaced that transistor, it just burned right through the new one as well (making my wife not very happy about the smell coming from the garage :). the fuse is intact; can the solenoid itself be shorted, but not trip the fuse? oh, and i've re-capped the sound board, if that matters, though the sound has been fine from when i bought it.

thanks in advance for any help!
 
#1 - dunno

#2 - yes, a shorted coil can burn up the transistor before (or never) blowing the fuse. Usually you can tell it's messed up because you can't manually move the plunger with your fingers....
 
#1 - dunno

OK - hopefully somebody else knows where i should look next...

#2 - yes, a shorted coil can burn up the transistor before (or never) blowing the fuse. Usually you can tell it's messed up because you can't manually move the plunger with your fingers....

ahh, right you are. i can't move the plunger at all. is there a good source for a replacement?
 
http://store.pacmandotcom.com/86-knocker-parts

Are the NV rams known good ones? I throw them in the programmer and write all F's to see if they are any good. If they dont program it usually means the battery is weak or dead and its locked out. If your using new parts you should be fine, although I just got a few dead ones from Jameco last month. Three of them suckers were used and two even had writing on them!
 
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thanks - that looks about right.

Are the NV rams known good ones? I throw them in the programmer and write all F's to see if they are any good. If they dont program it usually means the battery is weak or dead and its locked out. If your using new parts you should be fine, although I just got a few dead ones from Jameco last month. Three of them suckers were used and two even had writing on them!

i'm assuming they're new - ordered them from arcadeshop.com and they definitely look brand new. i don't have a programmer so can't be positive though i guess.
 
I bought 3 from them that were dead too. Checking the date code showed they were about 10 years old.

Probably the same batch im sure. I bought the last 20 or so they had in stock. For the price I didnt bother calling them and complaining about the three dead ones.

Elfy, the kocker assemblys and parts are original gottlieb parts and are a direct replacment. Most of the time you will only need a new coil to get them going.
 
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Elfy, the kocker assemblys and parts are original gottlieb parts and are a direct replacment. Most of the time you will only need a new coil to get them going.

i took the old one out and the plunger was just jammed way up and stuck. i pounded it out and it seems to be OK now (it moves in the sleeve when put together), but i want to be sure before i burn up another transistor. if i apply +30V across the terminals of the coil should i get the knock?
 
If it was jammed its because the coil sleeve melted. You might get lucky and the coil is ok but you will need a new sleeve at minimum.
 
Make sure the diode across the coil is good too. That keeps any tranisent spikes from traveling back to the transistor.
 
i ordered a new knocker coil and sleeve (thanks for the reference Riptor :)), and replaced them along with a new 2N6044 at Q2, and, BAM, knocker works great! thanks all for the advice.

but, still no luck on the high score saving issue. i made the fix on my second working board (remove battery, remove D2 and replace with jumper, and put in NVRAM), and it also doesn't work. i'm suspecting bad NVRAM now, since it doesn't work on either board, but want to be sure i understand two things: 1 - removing D2 and jumpering across is the right thing to do; 2 - with this fix in place, high scores should be saved even with a full power-down (unplug), right?

thanks again for the knocker help and for anything on the high scores...
 
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