Bally Lost World, not working advice required

[fleshy]

Last year I picked up a Bally Lost World (not working, reportedly working 2 years prior) for a couple of hundred dollars and would now like to spend time on a restoration.

General description
The back glass is in fairly good nick, there is a bubble in around the player 2 score display, but nothing has fallen away. The cabinet is faded, lots of wear around the flippers with several dents along the bottom side edges but nothing major. The playing field appears to me to be in great nick, there are no major chips or timber appearing under the paint work, all the rubbers appear to shot and the plastics faded and several plastic parts cracked. Over all the inside of the cabinet is fairly dirty, I had to clean several wasp nests out of the back box.

All of the boards appear original, some have test stickers on the from June 78.
MPU AS-2518-35
Lamp AS-2518-23
sound AS-2518-32
Solenoid AS-2518-16

On powering up all the bulbs light up, displays remain blank, there is no sound and the MPU led lights up and stays solid on. I tested the fuses and discover F2 was blown. When replaced the fuse immediately blew again. At this point I started looking at schematics to determine what F2 related to and as far as I can tell it is the display circuit (explaining the no-display at start up) Further reading leads me to suspect that the MPU may also be fubar, I've read that standard post is for the led to flash up to 6 times as it runs through system test, no flashing solid light is generally very bad. However I'm unsure if the MPU not booting and the displays not functioning are related or completely separate issues.

I'm now wondering what next? Any direction to what I should now be looking at or testing further would be of great assistance. If it is not already clearly apparent this is my first pinball experience.

[Toads]

I think you have 2 seperate issues.
F2 and the displays, I'd check the diode bridge cr1-4 for shorts.
Any battery damage on the Mpu?

[Strangeways]

  and   to the forum.

F2 is the 230VAC from the transformer. Remove the 20 pin connector (J3) on the Power Board. Change the fuse. If it still blows, you have a shorted CR-1 to CR-4. If not, then the problem will be on the Soldenoid Driver board. There should be a fuse on the SD board next to the heatsink. If this fuse is over rated, it will cause problems on the Power Board. Also, connectors on this board are almost always fried.

The CPU will flicker, first flash, pause, and then flash 6 more times (7 in total). Check for battery acid damage around the bottom section of the board.

The first step is always go back to the Power Supply and ensure the correct voltage are present. Remember, there is 230VAC floating around that board.

[Retropin]

The displays wont do a thing till the MPU is sorted.
The flash sequence will give you an indication of what MAY be wrong. The flash codes are detailed here.... take the diagnostics with a slight pinch of salt. For example, if you get a 3rd flash but not fourth then the PIA itself may not be defective but its logic voltage may be or its ground etc.... flash sequence basically points you in the right direction.
As Nino said, it will flicker first and then go through the flashes.
First job of any non working game is to make sure the power supply is running properly... get this going and move on from there

First Flash:
 Signals the end of the ROM test.


 Second Flash:
 Test the NMOS RAM (U7). There will be a bit of a delay between the first and second flash, be patient. If no flash, replace U7.


 Third Flash:
 Tests the CMOS RAM (U8). If no flash, replace U8 - use caution the 5101 chip is NOT diode protected and is very static sensitive!


 Fourth Flash:
 Tests the first PIA chip (U10). If no flash, swap U11 for U10. Note that although you may get the fourth flash, U10 may still be defective.


 Fifth Flash:
 Tests the second PIA chip (U11). As above. If you have already swapped U10 and U11 and don't have the fifth flash, try a new 6821 in U11. If still no success, swap once more. Worst case-replace both PIA's.


 Sixth Flash:
 Tests the Display Interrupt Generator. This actually tests both U11 and U12. If U11 has been replaced, and no sixth flash, replace U12.


 Seventh Flash:
 Tests the "Zero Crossing Detector". This tests U10 and U14 as well as the presense of +43 volts from the rectifier board. If no seventh flash, check for +43 volts before changing anything else. Fuse F4 (+43 volt) is a common failure. Unless U10 has already been swapped for a new or known good 6821, change it before U14.

[fleshy]

Thanks very much for the fast replies.

The MPU has the battery modded off board (3xAA batteries) other than messy solder work I can't detect any corrosion on the board. However the power is another matter, reading through you comments I went to researching the rectifier in more details and it is now abundantly clear that it has been hacked considerably and I think bypassed in a fashion. Basically there are addition blue and brown wires soldered to the back of the rectifier directly sending power to under the play board and the solenoid board. Half the wired from J3 have been cut short just above the plug.

I've taken a couple of photo's which will explain the issue much better than I can https://goo.gl/photos/ivKDF4ZtqceS75GX9 I've also taken a close up of CR1-CR4. In hind sight had I known more when I first posted I probably should have asked should I be replacing the rectifier board?

I'm unable to check the fuse with J3 pulled until tomorrow (is it still a worthwhile test given the current state of the wiring?), I suppose I could do some test point checking to see where power is going to from the back of the rectifier board.

[Strangeways]

Judging by those photos, I'd be looking at a homepin replacement ;

http://www.homepin.com/rectifierpcb.html

I've used these and they are fantastic - do you know how to assemble / solder electronic kits ?

[fleshy]

I've a friend who does quiet a bit of electronic work, he checked out the homepin manual and said it will be no problem. I've put an order in and will update in a few weeks. Thanks heaps for the help.

[Gemini2544]

You could have the wrong ROM wire links set on the board. I had a similar issue on a repair that came in once. It was soon discovered that we had the correct game ROMs in the MPU board but the board was configured for Star Trek. Once the links were corrected all worked fine.

[beaky]

i would be making sure you have 12V dc at TP2, and 5V dc at TP5 on the mpu board, if these voltages aren't right then you wont be getting any mpu to boot.
you need to check if you get a flicker then it locks on or if it just locks on straight away,
1st flicker indicates the cpu has booted and found the startup code in the rom at U6.
on rare occasions a faulty PIA at U11 can also make the led lock on,
it could just be a faulty cpu chip or faulty roms.
your mpu board looks pretty clean

But long term i would go the new homepin mpu board, they are so close to the original board except some things have been improved and obsolete I.C.s have been replaced with readily available I.C.s
They are repairable if they ever fail or are damaged and you don't have to worry about custom programmed chips failing and the board becoming a paper weight

the display fuse blowing is a separate issue as mentioned.