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IC-7000: Intermittent Loss of Pre-Driver signal
I've owned my IC-7000 for about three weeks, and it's now got an intermittent transmit fault affecting all bands.
The fault can be made to come and go when using the back of a small screwdriver to gently impact the PA Unit board in the pre-driver area of the board.? ? When the fault is on, I have TX signal at the gate of Q102, but no signal (or variable signal) at its drain.? ?The DC conditions on the gate and drain are consistently OK - regardless of whether the fault is present.? ?The TX signal at the drain of Q102 is highly variable between the fully working and fully non-working states.
Note:
All my measurements are being made at the components that I have access to from the bottom view of the PA Unit board.? ?To this extent, I must admit that I'm not making measurements directly on the pins of Q102 itself.
I'm currently attempting to isolate the fault, but do not know whether I'm looking for an intermittent open circuit condition, or an AC shunt path from the drain of Q102 to ground.
Has anyone here resolved a similar fault?? ? ?All tips gratefully appreciated.
With best wishes
Steve G4ALG
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Hi Steve I have not seen this fault personally. I am an ex radio technician of many years. And I own a IC7000 myself. From what you have described, I suggest the fault is more likely physical than electronic. Pressure on board would indicate to me a dry joint, or a hair line crack in a track or similar. The pressure could be moving a solder joint that looks OK visually, but has oxidized internally and only needs a bit of movement to make contact. One method to isolate, would be a can of freeze, spraying a small amount on tracks. Personally I would do a close visual inspection under bright light, even shining through board if necessary.? I have not had the covers off mine except to do fan mod, as it used to run very hot, that was cured by fan mod. Hope this is of some use in meantime. 73’蝉
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On 25 Nov 2024, at 3:23?AM, Steve G4ALG <steve@...> wrote:
? IC-7000: Intermittent Loss of Pre-Driver signal
I've owned my IC-7000 for about three weeks, and it's now got an intermittent transmit fault affecting all bands.
The fault can be made to come and go when using the back of a small screwdriver to gently impact the PA Unit board in the pre-driver area of the board.? ? When the fault is on, I have TX signal at the gate of Q102, but no signal (or variable signal) at its drain.? ?The DC conditions on the gate and drain are consistently OK - regardless of whether the fault is present.? ?The TX signal at the drain of Q102 is highly variable between the fully working and fully non-working states.
Note:
All my measurements are being made at the components that I have access to from the bottom view of the PA Unit board.? ?To this extent, I must admit that I'm not making measurements directly on the pins of Q102 itself.
I'm currently attempting to isolate the fault, but do not know whether I'm looking for an intermittent open circuit condition, or an AC shunt path from the drain of Q102 to ground.
Has anyone here resolved a similar fault?? ? ?All tips gratefully appreciated.
With best wishes
Steve G4ALG
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Hi Neal
?
I'm very grateful to you for your thoughts.? ?I have never used freeze spray, but I have heard good things about it when used for investigating intermittent faults.? I have now ordered a 600 ml can!? ?Old dog, new tricks.
?
Yes, all the soldered joints look wonderful.? But I guess that we've both been surprised by discovering a faulty joint that looked perfect from the outside.? I'm also wondering about the plated-through holes being another possible source of trouble.??
I'll update this thread when I have news.
If you have a reference for the fan modification, I'd be grateful if you could send it to me.
?
73
Steve G4ALG
?
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Hi Steve There are two fan mods.this is the one I did.
Contact author: M3SVO?
!! IF YOU ARE UNSURE ABOUT PERFORMING THIS MOD DON’T!!?
!!IF YOU DAMAGE YOUR RADIO YOU ONLY HAVE YOURSELF TO BLAME!!?
I have performed this mod on MY OWN radio without any adverse affects and my LDG AT-7000 atu still works as it should.?
Before this mod after been turned on for an hour or so the temp meter on the radio would show around 50% on the scale (7 or 8 bars), after the mod the temp meter shows around 25% on the scale (4 bars).?
First remove the top cover and remove the fan from the radio,?
take a 100ohm resistor and solder a length of wire to each end and cover with heat shrink tubing. Cut the red wire to the fan and attach one of the resistor wires between the two halves and cover with heat shrink tubing.?
Next follow the ORANGE wire from the ATU molex socket on the back of the radio to where it is soldered on to the DDS unit (top right hand corner at the back of the radio) and attach the remaining resistor wire to this point, position the resistor and wires so that they look neat and tidy and then refit the fan and the top cover, mod is now complete.
If you google IC7000 Fan Mod you will find other/s and other mods that have. Been done.
I have had no troubles with mine approx 12 years old now. Only issue is the mic cord split, which I have taped up with self amalgamating rubber tape in meantime.
73 Neil
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On 25 Nov 2024, at 9:14?AM, Steve G4ALG <steve@...> wrote:
? Hi Neal
?
I'm very grateful to you for your thoughts.? ?I have never used freeze spray, but I have heard good things about it when used for investigating intermittent faults.? I have now ordered a 600 ml can!? ?Old dog, new tricks.
?
Yes, all the soldered joints look wonderful.? But I guess that we've both been surprised by discovering a faulty joint that looked perfect from the outside.? I'm also wondering about the plated-through holes being another possible source of trouble.??
I'll update this thread when I have news.
If you have a reference for the fan modification, I'd be grateful if you could send it to me.
?
73
Steve G4ALG
?
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Hi Steve Yes plated through holes could also be an issue, I have seen where a track has cracked very close to donut on one side of plated through hole, very hard to see. I have also seen plated through hole holes where the graphite in the hole has not held the plating well. This can normally be fixed if there is room in hole by pushing a thin strand of tinned copper wire through the hole and soldering to tracks on both sides.
Hop this helps also. 73
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On 25 Nov 2024, at 9:34?AM, Neil Lintott via groups.io <nl3adc@...> wrote:
? Hi Steve There are two fan mods.this is the one I did.
Contact author: M3SVO?
!! IF YOU ARE UNSURE ABOUT PERFORMING THIS MOD DON’T!!?
!!IF YOU DAMAGE YOUR RADIO YOU ONLY HAVE YOURSELF TO BLAME!!?
I have performed this mod on MY OWN radio without any adverse affects and my LDG AT-7000 atu still works as it should.?
Before this mod after been turned on for an hour or so the temp meter on the radio would show around 50% on the scale (7 or 8 bars), after the mod the temp meter shows around 25% on the scale (4 bars).?
First remove the top cover and remove the fan from the radio,?
take a 100ohm resistor and solder a length of wire to each end and cover with heat shrink tubing. Cut the red wire to the fan and attach one of the resistor wires between the two halves and cover with heat shrink tubing.?
Next follow the ORANGE wire from the ATU molex socket on the back of the radio to where it is soldered on to the DDS unit (top right hand corner at the back of the radio) and attach the remaining resistor wire to this point, position the resistor and wires so that they look neat and tidy and then refit the fan and the top cover, mod is now complete.
If you google IC7000 Fan Mod you will find other/s and other mods that have. Been done.
I have had no troubles with mine approx 12 years old now. Only issue is the mic cord split, which I have taped up with self amalgamating rubber tape in meantime.
73 Neil
On 25 Nov 2024, at 9:14?AM, Steve G4ALG <steve@...> wrote:
? Hi Neal
?
I'm very grateful to you for your thoughts.? ?I have never used freeze spray, but I have heard good things about it when used for investigating intermittent faults.? I have now ordered a 600 ml can!? ?Old dog, new tricks.
?
Yes, all the soldered joints look wonderful.? But I guess that we've both been surprised by discovering a faulty joint that looked perfect from the outside.? I'm also wondering about the plated-through holes being another possible source of trouble.??
I'll update this thread when I have news.
If you have a reference for the fan modification, I'd be grateful if you could send it to me.
?
73
Steve G4ALG
?
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Neil ZL3ADC: Thank you.? I'll do the fan modification once the rig is working again.
To All:
Regarding the pre-driver device Q102, RD01MUS1.? ?This device seems to be most sensitive to tweaks of the PCB, but I have been unable to positively isolate the fault to Q102 with it still being soldered to the PCB.?
It would be helpful to know whether the device's Source connection is internally bonded to the Tab connection.? ?Both get soldered to ground on the PA Unit board.? ? I have found a data sheet at:
But it is not clear to me how to use the data sheet to ascertain whether the Source is internally connected to the Tab.? ?I would appreciate some help on this point.? Of course, if you have a RD01MUS1 on hand, I'd appreciate your observations with a test meter!
73
Steve G4ALG
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Hi Steve There are 2 voltages 2.81V and 8V mentioned on circuit diagram. The 2.81V appears as a voltage divider and feeds gate through a resistor and the 8V appears at drain through a couple of resistors. Is it possible to measure these while pressing on board to see if they change during fault condition.? As for question re tab of the driver device, it is not mentioned in data sheet if connected nor in picture. With the radio off you could try doing an ohms measurement between the tab and the 3 pins to see if any are connected. Try applying the pressure during this check as well if possible. Are you able to take a closeup photo of this area of the board to show us please. Hope this is of some help.
73 Neil
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On 26 Nov 2024, at 9:12?PM, Steve G4ALG <steve@...> wrote:
? Neil ZL3ADC: Thank you.? I'll do the fan modification once the rig is working again.
To All:
Regarding the pre-driver device Q102, RD01MUS1.? ?This device seems to be most sensitive to tweaks of the PCB, but I have been unable to positively isolate the fault to Q102 with it still being soldered to the PCB.?
It would be helpful to know whether the device's Source connection is internally bonded to the Tab connection.? ?Both get soldered to ground on the PA Unit board.? ? I have found a data sheet at:
But it is not clear to me how to use the data sheet to ascertain whether the Source is internally connected to the Tab.? ?I would appreciate some help on this point.? Of course, if you have a RD01MUS1 on hand, I'd appreciate your observations with a test meter!
73
Steve G4ALG
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Hi Steve I have had a look in the manual at the board, there are resistors on underside and mostly RF path on topside from what I can see. Can you indicate where you are putting pressure on the board, and how much.
It looks like the middle pin is also the tag, just by the way Q101 and Q102 are placed on board.. Were you thinking that the tag was poorly soldered perhaps? 73 Neil
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On 27 Nov 2024, at 12:04?AM, Neil Lintott via groups.io <nl3adc@...> wrote:
? Hi Steve There are 2 voltages 2.81V and 8V mentioned on circuit diagram. The 2.81V appears as a voltage divider and feeds gate through a resistor and the 8V appears at drain through a couple of resistors. Is it possible to measure these while pressing on board to see if they change during fault condition.? As for question re tab of the driver device, it is not mentioned in data sheet if connected nor in picture. With the radio off you could try doing an ohms measurement between the tab and the 3 pins to see if any are connected. Try applying the pressure during this check as well if possible. Are you able to take a closeup photo of this area of the board to show us please. Hope this is of some help.
73 Neil On 26 Nov 2024, at 9:12?PM, Steve G4ALG <steve@...> wrote:
? Neil ZL3ADC: Thank you.? I'll do the fan modification once the rig is working again.
To All:
Regarding the pre-driver device Q102, RD01MUS1.? ?This device seems to be most sensitive to tweaks of the PCB, but I have been unable to positively isolate the fault to Q102 with it still being soldered to the PCB.?
It would be helpful to know whether the device's Source connection is internally bonded to the Tab connection.? ?Both get soldered to ground on the PA Unit board.? ? I have found a data sheet at:
But it is not clear to me how to use the data sheet to ascertain whether the Source is internally connected to the Tab.? ?I would appreciate some help on this point.? Of course, if you have a RD01MUS1 on hand, I'd appreciate your observations with a test meter!
73
Steve G4ALG
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Hi Neil
?
Thank you, again.
The DC conditions on the gate and drain are consistently OK - regardless of whether the fault is present.?
> Were you thinking that the tag was poorly soldered perhaps?
With the FET still on the board, both the source and the tab are soldered directly to ground.? The reason I want to know whether the source and tab are connected internally is this:? From the side of the transceiver, I have been able to apply the soldering iron, and a little more flux and solder, to the drain and gate (the outermost terminals), and to the tab.? ?Applying the soldering iron (from the side) to the centre (source) terminal will be more difficult at this low angle of attack.? ?If the tab is internally connected to the source, I am happy that there is a good enough ground to the source.? If the tab is not internally connected to the source, I might be tempted to try to the re-solder the source terminal.??
I'll take a photo soon.?
I have ordered a replacement transistor for Q102.
More later . . . .
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Hi Steve It is not conclusive that they are connected from that data sheet. It may be that the tag is for heat transfer only and in this case is soldered to ground merely for that reason. If you could resolver that pin as well that could be the answer. When you said the voltages are consistent at the device, it really points to the device really doesn’t it? If the voltages varied it would point to a resistor/inductor on those voltage lines. I know it would be difficult to do, but if you could clear the solder away from all pins with solder wick and then reflow.
I await results when replacement device fitted. Best of luck with that. 73 Neil
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On 27 Nov 2024, at 3:17?AM, Steve G4ALG <steve@...> wrote:
? Hi Neil
?
Thank you, again.
The DC conditions on the gate and drain are consistently OK - regardless of whether the fault is present.?
> Were you thinking that the tag was poorly soldered perhaps?
With the FET still on the board, both the source and the tab are soldered directly to ground.? The reason I want to know whether the source and tab are connected internally is this:? From the side of the transceiver, I have been able to apply the soldering iron, and a little more flux and solder, to the drain and gate (the outermost terminals), and to the tab.? ?Applying the soldering iron (from the side) to the centre (source) terminal will be more difficult at this low angle of attack.? ?If the tab is internally connected to the source, I am happy that there is a good enough ground to the source.? If the tab is not internally connected to the source, I might be tempted to try to the re-solder the source terminal.??
I'll take a photo soon.?
I have ordered a replacement transistor for Q102.
More later . . . .
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Hi Neil
?
The soldering on the FET doesn't look as nice with my extra solder blobs, but I do feel that replacement of the suspect FET is now the next step.? This will be an IC-7000 strip-down task, risking ribbon cable damage etc..
?
If, when I receive the new FET, I find that the tab is isolated from the other terminals, I might be tempted to apply the soldering iron to the source (centre) terminal of the existing FET before taking the rig apart!
?
73
Steve G4ALG
?
?
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The fault on/off conditions are most sensitive to pressure applied to: the case of the FET (white arrow); the drain terminal; the gate terminal; and an area of the board near to L103 (white arrow).
?
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Hi Steve From the pictures, great job by the way. Under magnification looking at the plated through hole by the 560 ohm resistor and device it looks like there is a crack in the green coating, whether that is heat related from device, or is it the gremlin you are looking for? See if you can have a closer look the camera angle you took the pictures from would be great with more magnification. If it’s on a phone you may be able to see with light on and get a closeup view. ?I cannot see enough from the picture on the inductor side to say if there is any issues there. Here’s hoping! 73
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On 27 Nov 2024, at 8:11?AM, Steve G4ALG <steve@...> wrote:
? The fault on/off conditions are most sensitive to pressure applied to: the case of the FET (white arrow); the drain terminal; the gate terminal; and an area of the board near to L103 (white arrow).
?
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Thank you, Neil
?
I'll be sure to check the PTH, and surrounding area.? When the fault is 'off', the FET (Q102) really does get very hot indeed during normal use.? I suspect this really stresses the soldered joints -- especially as the soldered tab means that the device is 'constrained', such that large forces must be applied to the solder and foil/board interface as the device heats up.? ??
?
I'm going to give this some more thought, because I'd like to fit a small heatsink over Q102.? I see that Tasos SV8YM was also worried about the operating temperature of Q102:
?
As I look again at the photo, it's very tempting to think that I could swap Q102 without removing the PA Unit board from the rig? :-)
I don't want to spray this rig with shrapnel from my spring-operating solder pump, so I've just ordered some 2.5 mm wide Gootwick de-soldering braid.
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Steve, spring load solder suckers on smd's can be disastrous. 2.5 mm braid will take too much heat which could lift tracks and otherwise do damage. 1.5mm is much better for smd work.
Geoff
Thank you, Neil
?
I'll be sure to check the PTH, and surrounding area.? When the fault is 'off', the FET (Q102) really does get very hot indeed during normal use.? I suspect this really stresses the soldered joints -- especially as the soldered tab means that the device is 'constrained', such that large forces must be applied to the solder and foil/board interface as the device heats up.? ??
?
I'm going to give this some more thought, because I'd like to fit a small heatsink over Q102.? I see that Tasos SV8YM was also worried about the operating temperature of Q102:
?
As I look again at the photo, it's very tempting to think that I could swap Q102 without removing the PA Unit board from the rig? :-)
I don't want to spray this rig with shrapnel from my spring-operating solder pump, so I've just ordered some 2.5 mm wide Gootwick de-soldering braid.
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Hi Steve Saw the picture of the heatsink, you could probably do better with some copper plate. File it so it mounts the same but indented to touch the two devices case, add a bit of heatsink compound push it into place and solder it. Add a bit of high temp RTV silicon to hold in place perhaps. Then do the fan mod.
Agree with other person about size of solder wick, definitely not a solder sucker, as you ?say, there will be bits everywhere. If you could mask off the board and side wall you might get away with a sucker, your call on that one.
Re the PTH, you might have to remove board to get a wire through that hole if that is the issue. The device itself may have cracked underside and the stress is enough to make it work, especially if heat is an issue.
Hope there is a happy outcome.
73
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On 27 Nov 2024, at 3:12?PM, Geoff via groups.io <vk3zgw@...> wrote:
? Steve, spring load solder suckers on smd's can be disastrous. 2.5 mm braid will take too much heat which could lift tracks and otherwise do damage. 1.5mm is much better for smd work.
Geoff Thank you, Neil
?
I'll be sure to check the PTH, and surrounding area.? When the fault is 'off', the FET (Q102) really does get very hot indeed during normal use.? I suspect this really stresses the soldered joints -- especially as the soldered tab means that the device is 'constrained', such that large forces must be applied to the solder and foil/board interface as the device heats up.? ??
?
I'm going to give this some more thought, because I'd like to fit a small heatsink over Q102.? I see that Tasos SV8YM was also worried about the operating temperature of Q102:
?
As I look again at the photo, it's very tempting to think that I could swap Q102 without removing the PA Unit board from the rig? :-)
I don't want to spray this rig with shrapnel from my spring-operating solder pump, so I've just ordered some 2.5 mm wide Gootwick de-soldering braid.
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Thank you Geoff, and Neil ZL3ADC
?
I've now ordered some 1.5 mm Gootwick also!? ?I think that I'll do some practice with the braid on a scrap board before tackling the IC-7000.? I have found a useful video about the use of solder wick at:
?
I agree that a piece of copper plate would be better.? And thank you for all the other tips.? ?I plan to retain the copper plate with copper wire 'legs' to the PCB.? I'll be sure to use heatsink compound.
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Just a hint, the board and surrounding components are the primary concern when servicing.? There is no need to be "pretty" about removing a suspect part.? My first pass at this would be a wide, flat and hot iron with a blob of solder already on it, and flow the bad part off the board.? Then use braid to clean off the pads.
Mark K5LXP
Albuquerque, NM
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Removing the FET
Thank you, Mark K5LXP.? I had been pondering this aspect today, so your message is well-timed.?
?
I can easily heat all three terminals of the FET at once, but the tab (soldered to ground) will remain cold, and stop the FET releasing.? ? If I heat the tab first, then lever the device upward from the board from the tab end, the (still cold) terminals will cause the three pads to lift off the board.? It's a puzzle.
Do I need to fabricate an attachment for my soldering iron to heat the three terminals and the tab all at once?
Freeze spray
Well, the can of freeze spray arrived today.? It's not what I was expecting!? It's a can of propane and butane: a mix of fuel gases used for portable space heaters!? ?
And when I spray the contents, at the lowest possible flow rate, a large puddle of volatile liquid is formed over a wide area.? But the entire area does get very cold? :-)? ? ?I was expecting a can of inert stuff, that cools very small areas.?
What should I be looking for??
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its not a faulty plated thru hole? ?solder a piece of wire through to connect each side ?? cheers? Mike zl1btb
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Steve G4ALG