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ftm100 PA


 

what is a good procedure for removing the PA from the FTM100 motherboard? I have used solder wick to remove most of the solder but of course it is still attached. I have no special tools for that. Any ideas?


 

1)? At a bare minimum you need a hot air rework station.?

2)? Better is a hot air rework station and a PCB preheater.?

3)? Best is what I use which is a automated computer controlled rework station that runs through a stepped temperature PCB preheater cycle, stepped temperature reflow and automated suction pic of the part off the board.? Once set up it's a fully automated process.? After PCB cleaning it does basically the same but in reverse and after the new part has been reflowed onto the PCB goes through a stepped down cooling cycle.? It's the same machine I use for replacing BGA processor chips.

No matter what you use make sure you don't use more heat than needed or you risk damaging the PCB or thermally damaging the component.

Mikes Radio Repair
KC3OSD


 

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Dear Stanley,

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I good suction desoldering tool will help here to get as much solder off as possible, there are two ways, I find with a broad soldering tip and an iron of around 60-80 watts, flux the area and use a surgical scalpel to get under each leg and lift up, it gets easier the more legs you lift up, take it slow and steady, sometimes it helps to add a bit of fluxed fresh solder.

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If this does not work then there is insufficient heat from your iron, so stop, for example use a temp controlled iron like a Weller 1201A or WPS80,

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The second way is to cut the body of the transistor out then lift the legs, this depends on how much clearance you have?

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Make a note of any other component soldered close by, there are often base emitter and base collector caps to neutralise inductance.

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The 847 PA transistors are quite robust are you sure they are dead, ?check the bias set up procedure, the transistor bios pots have been known to fail, do you have 0.6 to 0.7V on the base of the PA transistors ?

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The previous stages are FET, so some 3-4Volts

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73

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Andrew G8UUG

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From: [email protected] <[email protected]> On Behalf Of Stanley Engel
Sent: 02 June 2024 16:05
To: [email protected]
Subject: [YaesuFT847] ftm100 PA

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what is a good procedure for removing the PA from the FTM100 motherboard? I have used solder wick to remove most of the solder but of course it is still attached. I have no special tools for that. Any ideas?