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View Full Version : Original Gollieb Q*bert Repair log WIP



Arcade King
10th May 2009, 03:47 PM
All you get when you fire the board up is scrolling horizontal lines. No sync.
I had to make a simple H/Vsync to csync adapter so I could work on the PCB on my test rig.

PCB has battery corrosion around the bottom left hand corner that covers about 1/4 of the bottom of the board about 2/3's the way across and about 1/4 of the way up along the edge connector. Removed the battery and sprayed the board with isopropyl alcohol to prevent further damage.

General probing.

Other bad IC's
74ls157 D2 through to D10. Replaced all 9 IC's. some were dead others were on the way out so best to replace the lot. El Salvador dated 8136

74ls374 @ D11 pin 16 stuck high
74ls244 @ D12 pin 3 was stuck low.
74ls86 @ D16, E15 and F17
74ls273 @ E16
These IC's have to do with the background generation.
I put in sockets because they were in the battery acid damaged area. After removing the IC's I cleaned the plated through holes the best I could using a fibre glass pen then dropped a socket in.

Replaced 4118 rams @ E7 and E10-11 for Hitachi 4116's, the legs were basically about to fall off. 4118's are 1kx8 while 4116's are 2kx8. pin 10 (A10) is already pulled High so a simple drop in replacement.
Also replaced 2 of the program roms for Hitachi ones to match the other 2 that were already on the board.

At this point I can see data there on my CRO but its just looping..
OK note to self Qbert has to have the test pin grounded for the game to run :b
Game is running great except all the character graphics are squished up. (see pic)

Problem turned out to be a 74s161 timer @ H5 I used a 74ls161 in its place. Those 74S161's get far too hot for my liking. I'm going to replace the lot with LS which work just fine. (The bootlegs use LS)

Game board now 100% but the sound board is another matter, the board uses some funky voltages. I attached a step down transformer to the cab yesterday so I could test the soundboard but unfortunately all I got out of it was garbage sound. I've just ordered a pair of SC-01-A Speech Chips from Kevin at www.GameRoomRepair.com so I can eliminate the speech chip before I start tearing apart the sound board. It could very well be a voltage problem also but its always a good idea to have some of these rare IC's on hand. lets face it the sound is what makes Q*bert so special.
I'll update the thread on the soundboard once I've received the IC's

First pic is of the GFX fault the rest are of the game running 100% :) The distortion on the left is just a monitor sync issue. I cant adjust the sync on my C1084s without pulling the case off.

stuba
10th May 2009, 07:23 PM
wow :o
can't wait to have a game on this ;)

Arcade King
10th May 2009, 09:14 PM
Just a quick update.

Decided to make myself up a quick bodgy backyarder Qbert to jamma harness so I could work on the sound board. I used a home made external AMP, the onboard amp needs 30VDC! I soldered the wire for the input to my amp on pin 9 of the qbert amp underneath the pcb.

http://www.aussiearcade.com/uploads/AK/IMG_1754.jpg

I divided up the PCB into 2 sections 1 for speech and 1 for general sound FX.
The General Sound FX were completely dead and the speech is just garbled.

Probing around I could see the sound working for the general sound FX via the outputs on the 74ls75's at U8 and U8 but the output (pin 4) on the 1408A DAC was stuck low IE Boned.
Luckily I have 2 scrap bootleg Qbert. While they are both missing the Speech chip circuitry they do have a single DAC on them for the general sound FX of the game.

FIX: Replaced the 1408A dac with a AM1408N8. All the general game sound is working again :D

I'm pretty sure the other DAC (U19) is fine because I can hear the garbled voices coming out the speaker. I will look over the speech chip circuit closer tomorrow but I suspect the speech chip is screwed. :(

If anybody knows a good source for these 1408A DAC's PLEASE let me know. I only have 1 left on the other bootleg.
Any of these will do
1408A
HA17408P
AM1408N8

Arcade King
21st May 2009, 06:16 PM
Had a small graphics glitch in the character graphics which developed while running the board for a few hours last week.

Problem: small flickering line on the right hand side of qbert and other character graphics.

Fix: Very easy to find. Touching the logic probe foreground roms address lines which increase the glitch specifically RA1 to RA4. Traced it back to a faulty 74ls379 @ K3

Just an update on the sound.

Got my SC-01-A's from Kevin but the speech is still screwed.

Problem: Speech is unrecognisable. Pitch of the sound is very low and long like its saying something far too slow.
Fix: Going through the data sheet of the SC-01 I read something that caught my eye.


MCRC (Master Clock Resistor-Capacitor) This input determines the internal master clock frequency. Select E C values for 720 khz to achieve standard phoneme timing
Connect this input to MCX when using internal clock, ground when using external clock.

NOTE
Varying clock frequency varies voice and sound effects. As clock frequency decreases audio frequency decreases and phoneme timing lengthens.

Looking at the Q*bert sound board schematics to see what's in circuit on the MCRC and MCX pins we have a LM741, 1408 DAC and a couple of transistors.
I socketed the LM741 and playing around with it I found I got correct sound or pretty close to it (but faint) by pulling pin 2 out of circuit. Pin 2 is connected to a variable resistor and pin 4 of the DAC which is the output.
Replacing the 1408 DAC @ U19 fixed the voice so essentially both DAC's on the board dead :( luckily I had the 2 bootlegs with these on it.
I'm relived the SC-01 on the board was ok now I have 2 spare :D
A 7407 died along the way in this repair but replaced with a NOS 74ls07
Q*bert sound is fantastic to be sure! so 80's

Very happy camper my Qbert is 100% working :D now Joey has fixed the chassis I should be able to play it tomorrow.

Mango
21st May 2009, 06:39 PM
I dont understand much of what you said but good job with the diagnostics to get it working :)

Arcade King
21st May 2009, 06:43 PM
don't worry I don't understand half the things I say either

stuba
21st May 2009, 08:13 PM
applause. man, that is awesome to see that game return from the dead. can't wait to have a game!

Foot
21st May 2009, 08:43 PM
Wonder what cab it's going in?

Mikie
21st May 2009, 08:50 PM
I dont understand much of what you said but good job with the diagnostics to get it working :)


+1 qbert is such a unique classic

Arcade King
21st May 2009, 08:55 PM
Projects ;) Now the boards are going I can start on the cabs.

WOKA
21st May 2009, 09:01 PM
Woohoo...! Nice dedicated cabs AK..

Arcade King
21st May 2009, 09:02 PM
I just finished the 240 volt conversion on the light fixture for Asteroids Deluxe so looking forward to playing that tomorrow backlit :D

Foot
21st May 2009, 09:03 PM
Very nice, they should come up great!

Didn't find an original Gyruss laying around anywhere I suppose

Mikie
21st May 2009, 09:46 PM
great cabs AK, yeah the qbert, gyruss and my favorite crystal castles are nice just to look at

stuba
22nd May 2009, 11:10 AM
sooo cool. original boards and original dedicated cab. awesome piece of history right there. :045:

hamish_nz
22nd May 2009, 11:19 AM
Wahoo a Q-bert Cab

wow :realmad: I am jealous

WOKA
22nd May 2009, 03:51 PM
Wahoo a Q-bert Cab

wow :realmad: I am jealous

Yeah right..! Mr 'I have MANY dedicated Cabs'..! ;)

hamish_nz
29th May 2009, 07:39 AM
you can never have to many :p

dezbaz
29th May 2009, 09:10 PM
Excellent!

Arcade King
29th May 2009, 09:45 PM
I've just been playing Q*bert for the last couple of hours can't get enough.

Small fault.
Knocker was locked on.

Fix. shorted 2N6044 Tranny @ Q2

Think I need a better Step down Transformer. With the knocker enabled every time it goes off the screen flickers and sometimes the game resets.
Any idea's what sort of transformer I need? I'm just using one I pulled out of a 20" lowboy ATM.

narf_
29th May 2009, 10:00 PM
i got a nice big namco one trav if you need a serious one

weighs a good few kgs though

dezbaz
30th May 2009, 12:00 AM
I've just been playing Q*bert for the last couple of hours can't get enough.

Small fault.
Knocker was locked on.

Fix. shorted 2N6044 Tranny @ Q2

Think I need a better Step down Transformer. With the knocker enabled every time it goes off the screen flickers and sometimes the game resets.
Any idea's what sort of transformer I need? I'm just using one I pulled out of a 20" lowboy ATM.

Isn't it a 30Volt knocker?

Could you use a lower voltage knocker from a pinball maybe, saves having to use a 30Volt Tranny

If you are using 12 volts to supply a 30v knocker it would pull in slowly and cause loading on the system i guess

EDIT I just realised you were talking about the 240/110 tranny, disregard above . . .

stuba
30th May 2009, 05:59 AM
how many amps is your step down? i have a 10 amp you could borrow to see if thats what the prob is..

Arcade King
30th May 2009, 08:24 AM
The step down im using is very tiny any only really meant to power the monitor on a lowboy etc not the whole PSU, lights and what not that's on these USA jobbies. Its getting far too hot I accidentally burnt myself on it last night lol

The Asteroids Deluxe says 175 watts in the manual but I cant find anything in the Q*bert manual about power requirements. I'm using a little lowboy stepdown in the Deluxe too but I've converted the fluros to 240 v so takes the strain off the stepdown.

Wondering if I just need a 250 watt or 500 watt stepdown?

voltages used on qbert

+5 gameboard
+30 sound amp and knocker
+12 sound
-12 sound
+20 coin metre
+4.5 coin door lights
and 110 for monitor and marquee.

I've already cut the plug off Stu
Cheers for the offer narf postage would be a killer tho?

narf_
30th May 2009, 10:08 AM
ill go weigh the beast mate

it would be around 500w or so

it used to run a entire alpine racer unit minus the rear pro (the tv had its own)

yeah just weight the beast is around 6kgs

Arcade King
30th May 2009, 10:26 AM
let me know what you want for it m8 and postage and ill fix you up right away.

narf_
30th May 2009, 10:44 AM
np

free just pay post ill post it tuesday (public holiday monday). ill sort it out tuesday mate

ill dig around i might have some yank plugs that connect straight to it also.

WOKA
1st June 2009, 09:54 AM
AK,

Not too sure if its what you need but I saw a portable 240 > 110v transformer at a garage sale on the weekend. One of those 'carry and plug in' jobbies. The sort Berty uses on his cabs.. Looks like a UPS. They wanted $25.00 for it. If interested, I can check to see if they still have it. Maybe not in keeping with Q*berts originality, but handy for other jobs..?

LMK

Arcade King
22nd May 2011, 03:50 PM
Been awhile since I've turned on the CRO and played with my logic probe but yesterday poor old Q*bert suffered a fault and I hate seeing good games suffer. :b goes out to Savage :D
I have 2 gameboards the original one that came with the machine which had bad corrosion (which I still fixed) and this minty one I bought from the states a few years back, cost me a pretty penny too!
Credit to the pcb its never had an issue up until now and was 100% in original condition. Only thing I've done was install a super cap.

Symptoms: Character sprites were in the wrong position. Imagine the screen split up into 4 equal vertical sections, sprites were all showing below where the should be and invisible in the other 2 sections.
Pics
http://www.aussiearcade.com/uploads/AK/qbert/IMAG0124.jpg

http://www.aussiearcade.com/uploads/AK/qbert/IMAG0125.jpg
As you can see Text and background layers are unaffected.

Fix: Had a similar issue with my other board so poked around the two 74S161 counter that are part of the line buffer address counter @ H5 and H6.
The culprit was the outputs on H6 pin 12 stuck low and 13 which was dead.
Simple matter of removing the IC
http://www.aussiearcade.com/uploads/AK/qbert/IMAG0127.jpg

Then put in a socket and new IC. 74LS161 is a suitable substitute for the S in this application.
http://www.aussiearcade.com/uploads/AK/qbert/IMAG0128.jpg

Result:
http://www.aussiearcade.com/uploads/AK/qbert/IMAG0133.jpg

http://www.aussiearcade.com/uploads/AK/qbert/IMAG0131.jpg

Q*bert is happily going about his block jumping business once again :)
Fair to note that on both boards and in both occasions the IC's were AMD branded 74S161's. I have no doubt the others will die eventually.

While I'm on the subject the 240 volt conversion thread may be useful to others HERE (http://www.aussiearcade.com/showthread.php/32942-Gottlieb-Q*bert-110-to-240v?highlight=qbert)

andykmv
22nd May 2011, 04:25 PM
nice restoration work trav!:)
just wondering - could you please post some pics of the inside of your coin door ?
gotta finish wiring loom fix for ben's qbert :cry, be useful to see another one!

Arcade King
22nd May 2011, 04:34 PM
which part specifically mate? the coin door itself or the test switches/volume?

andykmv
22nd May 2011, 04:39 PM
coin door itself! the door was missing the wiring for the coin slot lights, so will need to add that in. not sure what else your door may have that bens doesnt - acc to some klvers there was no coin lockout as std.

Arcade King
22nd May 2011, 05:07 PM
I've uploaded a couple HERE (http://www.aussiearcade.com/uploads/Crystal Castles.rar). Let me know if you need better ones.

andykmv
22nd May 2011, 06:20 PM
perfect! confirms some things for me as well, and shows the loom colours too. many thanks!

dezbaz
22nd May 2011, 09:16 PM
If anybody knows a good source for these 1408A DAC's PLEASE let me know. I only have 1 left on the other bootleg.
Any of these will do
1408A
HA17408P
AM1408N8

PM Sent not sure of their reliability

---------- Post added at 07:16 PM ---------- Previous post was at 07:10 PM ----------


PM Sent not sure of their reliability

Oops
really old post LOL :redface

Arcade King
22nd May 2011, 09:45 PM
Old post but I appreciate the heads up :) can never have to many spares.

Arcade King
25th November 2011, 03:57 PM
Just a quick repair log I just did on my Q*Bert which devloped a fault after a good days gaming from last Sunday with the boys.

Symptom: Text and background are a bunch of scrambled letters and number with some colour chunks. Character sprites are ok.
30759 30760

Fix:
With the schematics and some quick probing found the address lines at the ram at E10-11 on pins 1 to 4 (A4-A7) were dead on the 4118 background buffer ram. Tracked it back to a 74LS157 @ D9 which was Texas Instruments brand. Replaced with a nice Hitachi and alls good. :)
30761 30762

30763

visy
25th November 2011, 04:27 PM
Just a quick repair log I just did on my Q*Bert which devloped a fault after a good days gaming from last Sunday with the boys.

Symptom: Text and background are a bunch of scrambled letters and number with some colour chunks. Character sprites are ok.
30759 30760

Fix:
With the schematics and some quick probing found the address lines on pins 1 to 4 (A4-A7) were dead on the 4118 background buffer ram. Tracked it back to a 74LS157 @ D9 which was Texas Instruments brand. Replaced with a nice Hitachi and alls good. :)
30761 30762

30763

Sorry if I sound like a dumb ass. But what made you look at the address lines???
For all the board repair noobs it would be good to get some info as to what theory you based this investigation on. Past experience, gut feel, or some ram operation knowledge etc etc.

Arcade King
25th November 2011, 08:19 PM
All of the above really.
I've worked on a few Q*Bert PCB's over the years and have seen similar faults. Looking at the schematics (which are exceptional) it was easy to find what IC's are responsible for background generation.
I knew it would either be ram or what ever was driving it because I've seen many boards with garbage on the screen like what you see here.
The ram is all in sockets which makes life easy so with the board on I removed the background buffer ram at E10-11 which removed the garbage from the screen all together, this gave me a starting point. Using the logic probe I looked at each pin individually and found the first 4 pins dead. Knowing the pin out of the ram I know that those pins are address lines which are inputs so next step is to look at the IC driving those address lines which was the 74LS157 @ D9.

dezbaz
25th November 2011, 08:33 PM
:cool: :unbenannt :jump:

dave_wellington
26th November 2011, 04:11 PM
Hey mate, could you tell me how you made a CSYNC->H Sync/V Sync adapter? I need to do this for a new PVM style tube I got. Cheers!

Hewitson
26th November 2011, 04:39 PM
Did you try the schematic I posted for you over on AO a few weeks back?

http://www.epanorama.net/faq/vga2rgb/syncseparator.gif

dave_wellington
26th November 2011, 05:00 PM
Somehow I missed that, I only just today got around to trying the suggestion of linking H+V together (which didn't work, but apparently does in a lot of cases). Will give it a shot, cheers.

Arcade King
27th November 2011, 07:01 AM
Somehow I missed that, I only just today got around to trying the suggestion of linking H+V together (which didn't work, but apparently does in a lot of cases). Will give it a shot, cheers.

Yeah it wont.
Q*bert is a savage beast when it comes to sync and to be honest I've never made a H/V to C board that worked for me.
The photos in my last repair I took on the machine and I worked on the board blind. Luckily it was an easy fix and I was able to find the problem without needing to look at a screen.

Q*bert is the ONLY machine I own that still has its original Wells Gardner chassis, the rest have Joey chassis.

DKong
27th November 2011, 09:25 AM
Hey Trav, could you take a pic of your filter board, mine has a couple of hacks I want to check, also does your game PCB have some hacks ( they look factory) on the solder side around the middle from memory, mine has a few green wires , they look very neatly done and the board has no damage just want to confirm.

Cheers

Arcade King
3rd December 2011, 11:28 AM
Sorry for the late reply Ben I missed your post.
Yeah I have 2 boards the original that had corrosion that came with the machine and this really minty one I bought from the USA. I do recall it having some wire on the back and this is pretty common for Gottlieb. I have a revision one sound board here that is full of wires all from the factory.
The cab is hard to get out but next time I do I'll take a pic for you, I'm sure I took some of that area when Andy requested it??