Omaha, NE
Bad D25? If he's shorted then the battery will see just under a 220 ohm load. Pretty hefty load for a coin battery.
(Topic ID: 264686)
Linked Games
Family Guy
Stern, 2007
Topic Gallery
You're currently viewing posts by Pinsider G-P-E.
Click here to go back to viewing the entire thread.
Quoted from FiatsRUs:I put another button battery in to see if it also dies in a relatively short time. If so, I'll go the super cap route since my machines get turned on and played on a fairly regular basis.
Schematic shows that there is already a small super cap on that board at C255 (0.22F).
This super cap is intended to gloss over small dips in power but the battery is intended to hold up over time. You will get a higher mAH rating with a battery than a super cap. If your battery is not lasting long now, the super cap will be even shorter.
Yeah, the voltage at the anode of D28 would be due to C255.
Your readings mean the diodes are doing what they're supposed to be doing.
Next guess - something on board is drawing too much current. Bad RAM or the power control circuit within the DS1310.
Can you measure a voltage drop across R211 when the power is turned off?
Quoted from FiatsRUs:Drop is only 2.95 vdc to 2.94 vdc. I metered it with no battery in at just under 100 ohms.
Need to measure this one directly across the resistor. Red lead on one end of resistor, black lead end on other end of resistor. Just like you are measuring the resistance but with meter in voltage range.
Quoted from FiatsRUs:Do you mean the DS1302 at U43? Here is an entry from Pinwiki for the SAM system:
7.3 Battery draining quickly
A SAM CPU board was rapidly draining the battery when the game was powered off. Power was getting from the battery to the clock at U43 and the RAM at U11. In other words, the components on the way to the clock and RAM were good (R211, D24, R212) and the diode at D25 was also good. However, when setting the time under the Utilities menu, gibberish would be output when the last entry was accepted. This indicated a problem with the clock IC at U43. The clock is a SOIC-8 150 mil package. A replacement is DS1302Z+ found at mouser.com. After replacing the clock IC the game kept correct time when powered on and off, and the battery no longer drained quickly.
I am able to reset the time and date with no hiccups.
U43 may still have issues. This circuit has an internal power controller module. This power module selects between the 3V coin cell battery (when machine is turned off) and the 3.3V logic power (when the machine is turned on). It is possible for this to go bad yet still have a functional clock section.
OK -- you have a 100 ohm resistor with 0.0098V across it. This says you have a 0.0098/100 = 0.000098 amp load or 98uA. This is more than 10x what I expected but still not huge (I expect 6uA maximum based on data sheets).
The 24mm coin batteries are rated at 280mAh to 320mAh depending on brand.
280mAh / 0.098mA = 2448 hours = 102 days or just under 3 months. Not very good.
320mAh / 0.098mA = 3265 hours = 136 days or about 4.5 months. Better but still not very good.
The two devices share the same power source so not easy to narrow down which part is drawing excessive current. If the devices were socketed - you could pull them one at a time to see which one is the culprit. But... since these are SMT parts, that isn't really possible. I'm leaning towards the DS1302 - I would try separating pin 8 of the DS1302 from the battery power to see what the current load drops to.
Possible. The DS1302 is a RTC with an internal regulator. The regulator's sole function in life is to select between one of two power supplies (3.3V or battery) to provide power to internal clock and serial comm port. The regulator also includes a trickle charger for batteries. Even though the trickle charger isn't used, the 2 to 1 switch and regulator still provides internal power and can still fail.
As to which item OP is having issues with - it is still unknown. It can be either the DS1302 or the SRAM. Difficult to isolate since both are SMT. It was easier to change the DS1302 than the SRAM (8 pins versus 30/32 pins) so went that route first.
Promoted items from Pinside Marketplace and Pinside Shops!
You're currently viewing posts by Pinsider G-P-E.
Click here to go back to viewing the entire thread.
Reply
Wanna join the discussion? Please sign in to reply to this topic.
Hey there! Welcome to Pinside!
Donate to PinsideGreat to see you're enjoying Pinside! Did you know Pinside is able to run without any 3rd-party banners or ads, thanks to the support from our visitors? Please consider a donation to Pinside and get anext to your username to show for it! Or better yet, subscribe to Pinside+!
