SY85 INTERNAL BATTERY REPLACEMENT
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INTRODUCTION
The SY85 has an internal 3 volt lithium battery that keeps all the synth settings, internal patches, performances and sequences intact when the unit is powered off. It also supplies standby power to any SYEMB06 modules you may have installed.
If the battery voltage is low you could lose all your internal settings and a number of unusual problems may appear. Worst case is that the exhausted battery can leak and cause damage to the PCB and surrounding components.
The SY85 checks the internal battery voltage at power-on.
If your unit displays the message below at power-on you must replace the battery:
Change internal battery!
You can manually check the voltage of the battery by switching the unit on and pressing this button sequence to bring you into the diagnostics menu:
[SHIFT]+[STORE]+[EXIT/NO] all held down in that sequence.
When you enter the diagnostics menu a message similar to this will appear for a few seconds:
SY85 Test Entry <<< Welcome,Brother>>>
Main V1.20 14-OCT-1992/Sub V1.30S
The display will switch to the menu mode and will look like this:
[EXIT]=EXIT. [MENU]=FACTORY SET
[-1]=AUTO MODE, [+1]=MANUAL MODE
To check the battery voltage press the panel buttons in this sequence:
[+1] then [PAGE >] then [PAGE >] then [ENTER/YES]
The display will show the battery voltage screen:
02; BATTERY
3.0V OK
If your voltage is less than 3.0V you should think about changing the battery soon.
To exit out of the diagnostics menu press this sequence of buttons:
[EXIT/NO] then [+1]
The SY85 will now re-boot like it does at power-on.
BATTERY CHANGE PREPARATION
The SY85 will lose all its internal data during this procedure so if you have anything important in there you need to back it up now. This includes voices, performances, sequences and synth settings.
After the procedure you will need to restore all the internal settings to default using the Factory Set disk supplied with the SY85.
Points to consider BEFORE proceeding with this battery change procedure:
If you have no experience of soldering PCB components do not continue.
If you are thinking about doing this without the anti-static strap or workbench do not continue.
I am not responsible for any damage you do to your SY85, this is at your own risk.
Read the line above again!
Changing the internal battery involves opening the unit and removing the main PCB.
The battery type is a CR2450 with solder tags. To remove it you will need soldering tools and an anti-static wrist strap.
A good idea is that instead of replacing it with another solder tag battery you can use a CR2450 battery holder with a standard CR2450 cell. If you ever need to replace the battery again you do not need to remove the PCB or unsolder anything.
Note: The battery holder I used had a leg pitch of 20mm.
Items you will need:
o Yamaha SY85 Factory Set Disk.
o Anti-static wrist strap to ground yourself to an earth point.
o Work bench with anti-static grounded mat for PCB work.
o Soldering Iron.
o Solder removal braid to suck the solder out of the PCB holes.
o Philips 'star-head' screwdriver.
o CR2450 3volt cell.
o CR2450 battery holder with leg pitch 20mm.
o Multimeter if available to check battery voltage after change.
BATTERY CHANGE PROCEDURE
!! Unplug the SY85 from the mains supply !!
Time to use the anti-static strap and properly ground it to an earth point.
Remove any Wave and Voice cards from the slots on the top of the unit and place the unit face down on soft material.
Remove all the screws from the bottom cover except the screws marked in YELLOW.
There are two screw sizes used to keep the cover on. The screws marked in CYAN are the larger of the two.
Cover Screws:
Once the screws are removed lift the cover off to expose the internals.
The big white arrow points to the battery location at the top right of the main PCB.
MEMORY EXPANSIONS:
It would be a good idea at this time to remove any SIMM or SYEMB06 expansion boards and place them in a static safe area for now.
Isolate the battery from the rest of the PCB by removing the Jumper CP1 from the two jumper pins.
You can place the jumper on just one pin to prevent losing it as in the photo below:
Carefully remove the cable plugs out of the PCB left side connectors:
Connector CN12 is a tricky one!
You need to release the cable by lifting up the outside part of the connector first.
Carefully ease the cable out of the connector - patience needed here as it may not come out easily!
Remove the Front Left Connectors:
Remove the Front Right Connectors:
Remove the Right Side Connectors:
Time to remove the screws holding the PCB in place!
The rear of the PCB uses six coarse thread screws.
The front uses three fine thread screws.
PCB Left Side Photo ( 5 @ Rear, 1 @ Front Left ):
PCB Right Side Photo ( 1 @ Rear Right, 2 @ Front ):
This is the position of the screws holding the PCB in place:
Once all the connectors and screws are removed from the PCB tuck the cables under the PCB:
Tilt the PCB up and pull it forward and out away from the rear of the unit:
Place the PCB on a static safe area or workbench:
BATTERY REMOVAL AND INSTALLATION OF CR2450 BATTERY HOLDER
The original solder tag battery has three pins - one on the Negative tag and two on the Positive tag.
The easiest way to remove the battery is to target the single pin Negative tag first. Once you have that out of the PCB the two Positive tag pins can be worked a little at a time until the battery falls out.
Note that the Negative tag solders into two large copper planes on the top and bottom side of the PCB.
This has the effect of sinking the heat from the iron so you need to be patient when removing this pin.
Let the solder melt fully first before working at the pin.
Hold the iron to the Negative pin (right photo) and with gentle pressure lever the battery down so the pin is worked out of the PCB.
With the Negative pin now fully out of the PCB it's time to target the two Positive pins.
Target each pin in turn. Heat the pin and and gently tilt the battery away from it.
Keep alternating between pins until the battery finally falls out of the PCB.
With the battery now out of the PCB use the solder braid to pull the solder out of the Negative pin hole and the right-side Positive hole.
We don't need the left-side Positive hole for our battery holder so tidy any solder spikes or balls that may have formed when the battery fell out.
You may have to clear the Negative hole with the braid from both sides if the large copper planes prevent the solder from coming out fully from the PCB bottom side.
Now that the PCB holes are clear of solder the battery holder can now be fitted.
Fit the center Negative pin of the battery holder to the large copper plane hole.
Fit the outside Positive pin to the front right PCB hole.
Make sure the battery holder is flat on the PCB.
Flip the board over and solder the pins.
Now that the battery holder is in place you can put the 3V CR2450 cell in.
Depending on the make of battery holder you use there is a possibility that the battery may short-out for a split second against the retaining clip as you push it in. To prevent this happening hold the clip back with needle nosed pliers as you push the battery in.
When the battery is fully down into the holder release the retaining clip.
Do a quick voltage check on the battery.
Use the bare copper around the top right PCB mounting hole as a ground point.
A fresh battery should read around 3.3v
REPLACING THE PCB
Replacing the PCB is simply the reverse of the removal procedure.
Push the PCB in toward the back of the unit and ensure the Foot Controller Jacks and the Click Volume Knob locate through the rear panel holes properly.
Bring all the cable connectors from under the PCB back over to the top of the PCB.
Before inserting the PCB screws check that no cables have become trapped between the bottom of the PCB and the metal brackets that the PCB rests on.
For reference here is the photo again of the PCB screws.
The six coarse threaded screws go to the rear of the PCB.
The three fine threaded screws go to the front of the PCB.
Use the metal cable tie on the front left screw to hold the two cable looms at the front left of the PCB.
Replace the PCB screws first, then replace the cable connections.
The PCB screws are marked by Black & White arrows.
The cable connectors are marked with YELLOW arrows.
Reconnect the battery to the PCB by placing Jumper CP1 over the two pins ( left photo ).
It's a good idea to check the battery voltage at this stage incase there is an abnormal load present.
Use the Anode of D1 as the Positive point ( right photo ) and the metal bracket behind the PCB as the Negative point to take your voltage reading.
You should see a drop of about 0.01V at the Anode of D1.
There is a 10K resistor (R43) between D1 Anode and the battery Positive so any abnormal load on the battery is more noticable when probing D1 Anode.
Replace the Rear Cover.
Once you're happy all the internal parts are back in their proper place put the cover back on.
Remember to replace any SIMM or SYEMB06 expansion boards that were removed earlier.
The small screws go to the white circles, the large screws to the Cyan circles.
Flip the SY85 over and power it up.
You will notice all the presets have been lost and the synth setting are scrambled.
Load in the Factory Disk supplied with the SY85 to restore all settings back to default.
You can manually check the voltage of the new battery by pressing this button sequence to bring you into the diagnostics menu:
[SHIFT]+[STORE]+[EXIT/NO] all held down in that sequence.
When you enter the diagnostics menu a message similar to this will appear for a few seconds:
SY85 Test Entry <<< Welcome,Brother>>>
Main V1.20 14-OCT-1992/Sub V1.30S
The display will switch to the menu mode and will look like this:
[EXIT]=EXIT. [MENU]=FACTORY SET
[-1]=AUTO MODE, [+1]=MANUAL MODE
To check the battery voltage press the panel buttons in this sequence:
[+1] then [PAGE >] then [PAGE >] then [ENTER/YES]
The display will show the battery voltage reading similar to the photo below:
To exit out of the diagnostics menu press this sequence of buttons:
[EXIT/NO] then [+1]
The SY85 will now re-boot like it does at power-on.
Your new SY85 battery should give you many years of service :-)
-=- END OF SY85 BATTERY CHANGE PROCEDURE -=-
Written on 4th Oct 2009
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