Just got my first A2000! :)

[Oldsmobile_Mike]

Indivision ECS arrived today so I figured I'd check the battery while I had her open again.  If I understand the diagram Tenacious sent correctly this is a fairly simple circuit (keeping in mind I'm no electrical engineer).  Voltage should flow from the two positive terminals on the battery through the resistor at R803 and into the U801 clock chip.  I'm assuming the clock chip needs 3V, or close to it.  Actually the factory battery is marked as 3.6V on the diagram.

So with my multimeter I measured 2.9 volts directly between battery positive terminal and case ground, and 2.63 between R803 and ground.  If I understand correctly this is telling me I've got some degradation in the voltage along those tracks, but not much.  So logically thinking, If I put in one of those higher output batteries I should be fine, what do you guys think?  Or am I just totally off-base?  Haha.  

*disclaimer - am sure I'll wind up frying something!  

[QuikSanz]

Good Day,

When I bought my A2000HD the battery was starting to leak. I pulled the board out and then the battery. Once cleaned up I soldered a shielded wire (overkill) to extend the battery leads to a small board with a plug and and a new Varta battery. Screwed with standoffs behind the LED assy. Tidy and can't touch the board, a rev 6.2.

[Tenacious]

Your dropping some voltage across R803.  Gertsy may be right about the coin batteries not really having enough volts for this chip (same chip as other Amiga models?).  

You might try the neg probe (carefully!) on pin 9 to ensure your not reading a drop thru the case.

IIRC, the coin batteries are not rechargable like the original.  Is there a diode in this kit to prevent charging while powered ON?  Does it replace R803?

[GadgetUK]

Grats on your purchase!!  Looks tidy and minimal acid damage!

[gertsy]

......
So with my multimeter I measured 2.9 volts directly between battery positive terminal and case ground, and 2.63 between R803 and ground.  If I understand correctly this is telling me I've got some degradation in the voltage along those tracks, but not much.....

Hmmm that's sus. If I get you right there's a drop in voltage between the battery and the RTC chip. There shouldn't be. The voltage should be the same at both ends of the track. If you can test the voltage at the solder joint where the battery enclosure positive terminal is connected to the track, that will tell you where the problem is. It's possibly a short on the track or something wrong with the Amigakit coin battery unit. (Could be the diode has fried from overheating).

Testing voltages with the power off isn't going to fry anything as long as you are careful with the metal probe points so that you don't short between tracks or components. Which is fairly hard to do but can be done if you're a little clumsy.

[Oldsmobile_Mike]

Well, no love from my A2000 clock yet.  The new LIR batteries arrived (thankfully I ordered two - one arrived DOA!), but the other read a solid 3.6V on the battery itself, and 3.31V at the resistor.  I checked this on my spare A2000 board and noticed there's also about a .3V drop between those two points, so I'm sort of thinking this is normal?

Anyhow, set the clock and left it off overnight, and it's still showing the wrong time.  I'm suspecting my clock chip must be toast, any thoughts?  I'm not really adept enough with soldering to replace the clock chip, wonder if it's time to ship it off to someone else?  *sigh*  Should I check pin 9 for continuity to ground?  Am not 100% positive on which is pin 9, I think it's the top-right when facing the front of the system?

I also tried a variety of "setclock reset" and "setclock save" commands from the shell, just in case it was something in WB that was knackered.

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Also, why the bloody he** is OS3.9 so slow?  I don't remember it taking close to 3 minutes to boot up on my old A1200 back in the day, and I sure didn't have an 040 in my A1200!  Icons load at a glacial pace, and all I've got is a fresh install with all the Boing Bags, Visual Prefs, Full Palette (to use the Rebel 16-color palette), FBlit, and BlazeWCP.  I've already removed AmiDock.  Seems like the more patches I put in to try to speed things up the slower it goes, might have to revert back to MagicWB icons, LOL.  :p

[GadgetUK]

Well, no love from my A2000 clock yet.  The new LIR batteries arrived (thankfully I ordered two - one arrived DOA!), but the other read a solid 3.6V on the battery itself, and 3.31V at the resistor.  I checked this on my spare A2000 board and noticed there's also about a .3V drop between those two points, so I'm sort of thinking this is normal?

Anyhow, set the clock and left it off overnight, and it's still showing the wrong time.  I'm suspecting my clock chip must be toast, any thoughts?  I'm not really adept enough with soldering to replace the clock chip, wonder if it's time to ship it off to someone else?  *sigh*  Should I check pin 9 for continuity to ground?  Am not 100% positive on which is pin 9, I think it's the top-right when facing the front of the system?

I also tried a variety of "setclock reset" and "setclock save" commands from the shell, just in case it was something in WB that was knackered.

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Also, why the bloody he** is OS3.9 so slow?  I don't remember it taking close to 3 minutes to boot up on my old A1200 back in the day, and I sure didn't have an 040 in my A1200!  Icons load at a glacial pace, and all I've got is a fresh install with all the Boing Bags, Visual Prefs, Full Palette (to use the Rebel 16-color palette), FBlit, and BlazeWCP.  I've already removed AmiDock.  Seems like the more patches I put in to try to speed things up the slower it goes, might have to revert back to MagicWB icons, LOL.  :p

Get the schematics out and trace connectivity to each pin on the clock chip from agnus or wherever it's supposed to connect.  It could be the variable cap affected by corrosion as well - you could probably take one from a 500 memory expansion.

[Tenacious]

Get the schematics out and trace connectivity to each pin on the clock chip from agnus or wherever it's supposed to connect.  It could be the variable cap affected by corrosion as well - you could probably take one from a 500 memory expansion.

Good idea.  As a cross check, chip pins are numbered counter-clockwise (looking down on the component side of the board) around the body from pin 1, which is the next pin after the notch.

You could confirm power to the chip while powered up.  

You are certain there is no moisture remaining under this chip?  Check continuity from pin to pin and cross check to the schematic.

EDIT:

With a scope or possibly a logic probe, you could test for a pulse train out of Y800.

If you replace U801, use a solder sucker AND solder wick (Radio Shack) to remove as much solder as possible.  It would hurt the MB the least to gently snip the old chip out and then remove each remaining pin individually.  When you install the new one, align the notch.  Sparsely apply solder to the pins on BOTH sides of the board to ensure that all the layers in the MB are connected to each pin.

It would be a shame to waste the work you have in this board already.

[Oldsmobile_Mike]

Haven't had much time for this, still no love.  With power off pin 18 is showing exactly the same voltage that I'm getting at the resistor (so the chip is getting power), and pin 9 is showing continuity to both case ground and Batt negative.  It's a pretty high resistance, but I compared it with my spare A2K motherboard and the measurements are about the same.

I also checked the positive sides of 811 and 812, not exactly sure what those components do but I know they're getting power.

Will try to find time to check more pins soon, taking the drive sled out over and over is getting pretty old, LOL.  :p

[Oldsmobile_Mike]

Also zero resistance between Batt Negative terminal and case ground.  I'm checking easy stuff first, LOL.  

If I do have to replace the clock chip at least I see plenty of them on ebay... think I'll socket it.  

[QuikSanz]

Good Day,

Try reseating the main chip, may be a bit loose/poor contact.

Chris

[Oldsmobile_Mike]

Try reseating the main chip, may be a bit loose/poor contact.

Main chip - U801 - is soldered directly to the board.  Wish it were that easy!  If I wind up feeling daring enough to replace it, I'm going to socket it.  18-pin sockets are only .50 cents on ebay.  :p

[QuikSanz]

Hmm, If the solders are all good then it probably has some bad cache and has no place to hold the time. A socket is a good idea.

Chris