Bally 5500 - no LED display

[Midcoastsurf]

I am using 3AA with a blocking diode. I can swap out for a 3.6V. I didn't think this would cause an issue, but it sounds like it might.

[Badbaud]

Give it a try. If that doesn't work remove the socketed IC's and clean their legs.

I have fixed many boards by simply cleaning corroded IC pins.

[Midcoastsurf]

Ok. I already cleaned the legs on the one chip. Are you referring to all the labeled chips to the left of the two chips I pulled?  Thanks for all the advice!

[Badbaud]

And the small, long, chips to the right.

[Midcoastsurf]

Pulled the chips and re-seated. I didn't see any corrosion on the pulled chips. Put the board back in and there is no change. I get the same strange message in the displays and trying to do a clear yields no display message.

[Badbaud]

Besides sending the board in for repair to K-LAR 702-363-9998 here is one other thing I have found fixingthose boards.

On the bottom side of the board where the battery + lead goes there is a very tiny PCB trace that gets broken off when the battery leads are soldered from the top.

Check to make sure that trace didn't get broken.

[Midcoastsurf]

I replaced the 3 AA set up that was putting out 4.3VDC with the regular 3.6vDC battery.  I am measuring about 3.4vDC at the chip.  I checked the continuity of the trace below the "+" sign on the battery to where it goes to the leg of an IC, and I do get continuity, so no broken trace.

No change after the battery swap, but I can no longer bring up the weird error message, "n.FE.7", "F.FF4".  No idea what this means as it's not one of the error messages listed in the manual.

What is the typical price for a working S5500 board?

Thanks

[Badbaud]

We don't swap boards. We get out the scope and determine whats wrong and fix it.

Send Larry the board.

I don't know if I mentioned this but as a last resort remove both RAM chips and swap their locations then try clearing the board one more time.

Your original post mentioned something about no display. I assume you are getting some kind of display now?

[Midcoastsurf]

I did try swapping RAM chips.  I get nothing on the display, but I have seen that strange error message once in a while. I'll try swapping my display board into an S5500 locally to see if it's working properly.  I also sent a note to Larry.

Thanks!

[Midcoastsurf]

Should there be a message on the display even if the MPU is missing or needs work? 

[Badbaud]

Never seen a message without the MPU.

[Midcoastsurf]

Had a friend try the board in a know working 5500 machine and his game shows nothing on the screen And won't clear (same as my machine).  Must be board related. Voltage from battery is good.

Looking through a few repair logs, looks like U71 and U34 are common replacements for this issue. Does anyone sell these chips?

Thanks

[Badbaud]

Chip numbers not location numbers please.

[Midcoastsurf]

Chip numbers not location numbers please.

I don't see any numbers on the U71 chip. Here are pics of both:

[Badbaud]

U34 is a UART comm chip and I have seen those go bad but mostly in Bally 5000 boards not 5500.

The other chip has a number under the label and it is the main computer chip.

I know we have plenty of those U34 chips but those 64 pin computer chips are hard to find.

In the past simply moving every socketed chip out of it's socket slightly (raise one end a little then press back in then the other end) has gotten a dead board to work but you may want to check your power supply also. See attached test points for the power supply, test while it is in the machine with power on.

No test jumper necessary if you are testing inside the machine.

If those voltages are low or missing the board won't work.

[Midcoastsurf]

The voltages on the PS are good and I also tried the board in a working 5500 with the same results. I reseated all chips that are socketed. I'll try the large chip again.

Here is a pic of the large chip with the sticker removed.

[Badbaud]

It may be time to send the board to Larry.