Self testing- wait for a while

[cliffeby]

Picked up this Sigma 300 over the weekend. Replaced the battery and had everything but the upper display and printer working. Left it on overnight and woke up to off and on slow spinning reels. Checked the power supply and have 5, 12, and 23.8vdc. Now getting this message after two slow reel spins.

Any advice?

[Chris-socal]

You usually have to activate BV after battery change, but that comes after a good start.
What kind of battery did you install? They usually have backup capacitors (they look like coin shaped batteries but they are really a capacitor). You can replace them with a rechargeable battery…but usually you just let them run for awhile and they charge up.

As for the persistent error, have you tried starting the machine while holding the inside button? Sometimes it clears, depends on which board you have…they used at least two different versions. Post a picture of the board if you can. Some of the early SG300 used the old style boards.

Handle the board with care, there are tons of Logic ICs on them and they are notorious for traces breaking when people work on them.

Chris

[cliffeby]

As shown, battery replaced with a 3v coin cell. Now reads 2.95v. Have not tested any voltages under load.

I’ve tried all startup combinations of red push button and jackpot reset key with no change in behavior. Both worked properly when i reset it after the battery install. Up until leaving it on overnight, the maximum time under power was 1 hour.

Thought that I had an easy fix!

[Chris-socal]

If you use a coin cell you need to inactivate the charge circuit…unless it was already converted to a non-rechargeable battery. The battery could get really hot and potentially blow up. Truth is, the backup capacitor was probably fine, they just need to run for a long time and charge very slowly.

That is the new form factor of board with SMD technology. More stable but very difficult to probe and troubleshoot. Sorry I don’t have any specific suggestions other than pull up a schematic and start verifying component activity.

Chris

[Chris-socal]

Wait, you replaced one battery, what is the second backup capacitor there on the lower left of the image, close to the first one you replaced? Check voltage on that one too, but if it charged overnight it should have some juice.

[cliffeby]

Before I got your message, I replaced the new battery since it was at 2.95v. Second new battery was 3.2v but once inserted down to 3.1vdc. Got a draw somewhere.  Machine plays and credits remained. Assume it won’t last long.

The capacitor was already there. Will check the capacitor voltage later today with the power off. The original battery was a 2330.

[cliffeby]

Returned home and the second new battery was down to 2.9vdc. Got the “wait for a while message” when I turned on the power. Capacitor was 3.6vdc and declining . Increasing when power is on.

[Chris-socal]

The capacitor is designed for a limited amount of backup period, not in terms of years like we are accustomed to in newer games. But, the drain should not be visible noticeable. Plus, it it has been sitting for years they take time. Those are usually 4v or 5v capacitors. Its possible the battery was installed and the charge circuit was not properly disabled or un-jumped and the diode is shorted. And yes, you could have a defective memory retention IC that has excessive drain. Hunt down the load.

[cliffeby]

Both the capacitor and the diodes test bad. Will replace and keep my fingers crossed. I don’t see a chip on the board that looks like a traditional sram. I see the 8pin eeprom.

[Chris-socal]

Thats actually a good find Cliff

The capacitor will not test as a regular capacitor. It is designed for a very slow charge and storage.
The diode certainly needs to be replaced and the battery needs to be of rechargeable type. These machines have a circuit that tests the SOC and will not boot without a backup source. However, leaving the backup capacitor on charge for a few hours already showed you that it takes a charge, I would not change it at this point. You nneed to resolve the backup circuit so it is not draining the batteries.

Chris

[cliffeby]

I replaced the diodes (used 1N5817 Schottky Diodes) and the ELDC capacitor.  It took several reboots, but it now seems to function properly.  Will leave it on overnight to make sure.   Thank you.

Now on to its other issues - no coin comparator (will be posting for one with $1 tokens), bill acceptor needs a rehab and update, and then on to the display panel and card reader in the upper panel.

[Chris-socal]

The BV should accept $1 bills at least. Many of the Sigmas were updated to accept new bills. You do have to activate the BV in setup though. Also open the head unit and clean the lenses with a damp cloth….no alcohol or glass cleaner…just damp with water.

Glad to hear fixing the charge circuit worked. Those machines are fun and have good sound….for the era.

Chris