Topics

QCX TROUBLESHOOTING


David R. Hassall WA5DJJ
 

Dear Group,

 

I am working on some QCX’s that folks have given me and trying to get them working.   Most times this is a really straight forward job but every once in a while you get a real Challenge.   I have a QCX on the bench right now that I have been working on for three days.   Some of the problems I have found was a bent under pin on the processor, two dead OP AMPS(U5 and U8)  numerous cold solder joints and a couple of solder bridges, most of the leads were soldered but not cut off close to the board.   I have gone through a complete check of the resistors being soldered in the right spots.  I did check some of the capacitors but not all.   I found a couple of the ground plane’s has somehow lost their interconnection to ground (that one really got me good).   I have rewound T1, L1, L3, L3 and L4 as they were wound backwards or jumbled up so bad I couldn’t tell what I had and I measured each one with my L/C meter to make sure they were close before reinstalling them.  There were about 6 PC board traces that had lifted and I repaired them with a small wire.   But it still doesn’t work.   My Bias voltages are low. The inputs from IC4 to C43 through C46 according to the voltage chart should read somewhere around 2.28V to 2.48 Volts.  Mine seem to read about 1.65 Volts.   When I install the 330 ohm resistor across R43 so you can use a scope to trace the waveforms through U5 on, I can see the waveform and the 90 degree phase difference and after replacing U5 and U8 using this procedure I could finally get a sound out of the speaker.   But as soon as I take the 330 ohm resistor out and do the BPF alignment  the receiver is dead.   My bias measurements on the rest of the OP AMP are about a  volt low.  I used the troubleshooting procedure.  I even hooked up the radio to a good 12V 2A wallwart and did the measurements with the internal test equipment voltmeter, then redid the measurements with My Bench meter and most of them are the same.

But the main glaring error is that the approximate 2.5 volt bias in the receivers op amps does not exist in this radio.    It is at about 1.5 Volts on IC5, 6, and 7 and goes to .85 on IC8 (which I know is low but until I can get the others up to the correct value, I have not troubleshot this problem.   In all of this the strangest thing is the Transmitter side works perfectly.

 

I realize I have a tiger by the tail with this QCX.   I expect the reason I ended up with it is because I needed a lesson in HUMILITY.   I think this is a training aid and IT HAS EVERY PROBLEM that has been mentioned on this website all in one QCX.

But I am determined to get it running.   So, my worry now is that I don’t see the 2.4 Volt bias signals out of IC4.  My measurements at C43 through C45 are only 1.65 volts using the internal meter.   Does this mean that  U4 is bad? It has 5VDC on pin 14 and GND on pin 7.  The SI5351 inputs appear normal and phase shifted.  Since every unit of this series of kits has worked for me when I built them, I am unfamiliar with the inner workings of this stage and I am trying to decide what my next troubleshooting step is going to be. 

 

So, can anybody help me out here.   Thank you for your time.  

 

73 Dave Hassall WA5DJJ  Las Cruces, New Mexico

Website: http://www.zianet.com/dhassall/

QRSS SUPER GRABBER WEBSITE: http://www.qsl.net/wa5djj/

 


Michael Greene
 

Dave,
Forgive me for commiserating. My unit worked right after building it (aside from an overly tightened LCD screen, which was quickly remedied). Then, I shorted out a pin from +12V and have been dealing with issues ever since. I'm still working on it and it was a TRUE lesson in humility (I'm a novice, so to be expected). But, I have learned this kit and have a lot more to learn on my way through the repair process. Your skills are way ahead of mine, so I can't offer advice, only appreciation for what you are doing. I often come up with ideas by reading the manual, looking at the schematic, probing the board and then just getting away from it to get ideas to pop in my head while lying in bed. Best of luck! And most of all, thanks for helping all those folks to get their QCX's working!
Michael


Evan Hand
 

Dave,

I am guessing here, so please do not laugh.  Did you measure the voltage between R1 and R2?  That sets the bias assuming IC4 is working as it should.  If you do not have 2.5 volts there, you will not have it on the capacitors.

If the voltage is low there, then remove the T1 leads and measure again.  If that is 2.5, then IC4 has the issue, or there is a trace problem around that area.

Again, I have not done much work with the QCX, so I may be way off.

73
Evan
AC9TU

Edited to correct a typo.


Shane Justice
 

David,

If I remember correctly, the voltage divider that forms the bias for T1 S1&S2  goes to +5VDC. If you have 5V at the top of these two resistors, you should have 2.5V. at the junction of these two resistors. You should see this same voltage at the I & Q inputs to the first opamp in the IQ chain. If you don't have these volages here, it's probably first business to get that working, before moving forward. 

Check the output of this opamp and all those forward. If any input or output doesn't have the listed voltages, check to make sure the power supply votages is as expected for each opamp in the chain. If the power supply voltage is off, you won't get the output voltage you expect. 

Otherwise, the gain of each stage is a function of the two input resistors to the opamp and the feedback resistor of each opamp. Verifying the values of the resistors is as important at the volatges fed to the opamps, so that should be checked. If you haven't done so, power down the radio and check for shorts or low resistance to ground at each input and output of the opamp chain. If you find nothing, it's worthwhile to look for low impedance and shorts to power supply rails. Something blew those opamps. There's a short list of what could have done that, outside of slipped probes bridging signal pins with power rails. Maybe check pins 7&8 of each opamp, as that is the most convenient place to make that sort of damage with a simple slip of the probe tip.

Let me know if I can help. We can chat on the phone, pm, Skype, zoom, etc, if you'd like.

73,
Shane
KE7TR

On Oct 27, 2020 at 16:02, David R. Hassall WA5DJJ <dhassall@...> wrote:

Dear Group,

 

I am working on some QCX’s that folks have given me and trying to get them working.   Most times this is a really straight forward job but every once in a while you get a real Challenge.   I have a QCX on the bench right now that I have been working on for three days.   Some of the problems I have found was a bent under pin on the processor, two dead OP AMPS(U5 and U8)  numerous cold solder joints and a couple of solder bridges, most of the leads were soldered but not cut off close to the board.   I have gone through a complete check of the resistors being soldered in the right spots.  I did check some of the capacitors but not all.   I found a couple of the ground plane’s has somehow lost their interconnection to ground (that one really got me good).   I have rewound T1, L1, L3, L3 and L4 as they were wound backwards or jumbled up so bad I couldn’t tell what I had and I measured each one with my L/C meter to make sure they were close before reinstalling them.  There were about 6 PC board traces that had lifted and I repaired them with a small wire.   But it still doesn’t work.   My Bias voltages are low. The inputs from IC4 to C43 through C46 according to the voltage chart should read somewhere around 2.28V to 2.48 Volts.  Mine seem to read about 1.65 Volts.   When I install the 330 ohm resistor across R43 so you can use a scope to trace the waveforms through U5 on, I can see the waveform and the 90 degree phase difference and after replacing U5 and U8 using this procedure I could finally get a sound out of the speaker.   But as soon as I take the 330 ohm resistor out and do the BPF alignment  the receiver is dead.   My bias measurements on the rest of the OP AMP are about a  volt low.  I used the troubleshooting procedure.  I even hooked up the radio to a good 12V 2A wallwart and did the measurements with the internal test equipment voltmeter, then redid the measurements with My Bench meter and most of them are the same.

But the main glaring error is that the approximate 2.5 volt bias in the receivers op amps does not exist in this radio.    It is at about 1.5 Volts on IC5, 6, and 7 and goes to .85 on IC8 (which I know is low but until I can get the others up to the correct value, I have not troubleshot this problem.   In all of this the strangest thing is the Transmitter side works perfectly.

 

I realize I have a tiger by the tail with this QCX.   I expect the reason I ended up with it is because I needed a lesson in HUMILITY.   I think this is a training aid and IT HAS EVERY PROBLEM that has been mentioned on this website all in one QCX.

But I am determined to get it running.   So, my worry now is that I don’t see the 2.4 Volt bias signals out of IC4.  My measurements at C43 through C45 are only 1.65 volts using the internal meter.   Does this mean that  U4 is bad? It has 5VDC on pin 14 and GND on pin 7.  The SI5351 inputs appear normal and phase shifted.  Since every unit of this series of kits has worked for me when I built them, I am unfamiliar with the inner workings of this stage and I am trying to decide what my next troubleshooting step is going to be. 

 

So, can anybody help me out here.   Thank you for your time.  

 

73 Dave Hassall WA5DJJ  Las Cruces, New Mexico

Website: http://www.zianet.com/dhassall/

QRSS SUPER GRABBER WEBSITE: http://www.qsl.net/wa5djj/

 


Ralf Rosche
 

Hi Dave,
the opamps are very robust, so i don't think you killed them.
Please check thoroughly the soldering of these opamps. The groundconnection (Pin4) causes sometimes problems.
Ralf


David R. Hassall WA5DJJ
 

Thanks Evan,  I thought I checked that but I will go back and check it again.   I did check the resistor color codes for every resistor on the board and their position to make sure they were in the proper holes.   But I looked back on my voltage sheet and the T1  pins 5, 6, 7, and 8 voltage was 1.65 Volts.  and It is listed as 2.36.   So I will revisit that area and see if I can detect a problem.   What you said makes sense to me now.  Like I said, I have never had to troubleshoot this area in all of the QCX's I have built or worked on.  This always worked. 

Take care and have fun.
73 Dave WA5DJJ


David R. Hassall WA5DJJ
 

Thanks Shane,  One of the first things I did was check all the resistors and their color codes to make sure they were in the right spots.   I usually find most of the difficult problems in that step.
I look back on my voltage measurements and T1 pins 5, 6, 7, and 8 voltage should be 2.36 volts.   My unit measures 1.65 using the internal test equipment.  So there is a problem there and that will be where I start today.   For some reason I am not getting the even division of the +5VDC.   Evan also mentioned this in his email
Take care and have fun.
73 Dave WA5DJJ


David R. Hassall WA5DJJ
 

Dear Ralf,
I agree that they are very Robust.   But there was just no signals going through the two I replaced.  After replacement there was signals.  Since I have no idea what the history was on this unit and in the interest of maybe saving some time, I went ahead and replaced them.  Judging from the burnt traces on the PC board and other factors, even robust op amps can be destroyed.
So, I am moving on in a quest to get the voltages right.  I am sure there are more wonderful things to discover.


Shane Justice
 

Dave,

Good stuff! That voltage divider is worrisome.

I am in Vail AZ, about 5 hours West of you on I10. I'd be happy to come out your way and bring my test equipment scope, dvm, LCR meter, spectrum analyzer, minivna, Hakko fr301, etc. I'll stay in a hotel for as long as necessary to help you get that unit up and running. I just need to be in Vail to vote on Tuesday.

Let me know how I can help.

73,
Shane


On Oct 28, 2020 at 06:39, David R. Hassall WA5DJJ <dhassall@...> wrote:

Thanks Shane,  One of the first things I did was check all the resistors and their color codes to make sure they were in the right spots.   I usually find most of the difficult problems in that step.
I look back on my voltage measurements and T1 pins 5, 6, 7, and 8 voltage should be 2.36 volts.   My unit measures 1.65 using the internal test equipment.  So there is a problem there and that will be where I start today.   For some reason I am not getting the even division of the +5VDC.   Evan also mentioned this in his email
Take care and have fun.
73 Dave WA5DJJ


David R. Hassall WA5DJJ
 

Dear Shane,
Thanks for the offer but I have just about the same stuff in my shop to attack a defenseless 4" circuit board and a bunch of parts.  I think I will be able to handle it as soon as I figure out what is going on with it.   The chase is half the fun of fixing it.   Today I replaced the LM7805 +5VDC regulator as it was drooping and wasn't putting out +5VDC.   The new one is at 5.02 VDC.  I also changed the two 10K resistors R1 and R2 with a pair of 1% 10K resistors.   That brought the voltage up to 1.98VDC but not to the 2.5 Volts I was expecting.   Looking at the circuit the only load for that voltage divider is the Quadrature Sampling Detector IC4 a surface mounted FST3253 of which I do not have.  So, I will work on getting a few and replace that one.  This is a case of it is the only thing left in the circuit that doesn't work.   There is also still another mystery lurking around IC7 and IC8 that is also causing problems.    So, It is just a wonder how this much stuff can be bad in just one kit.    I have a 40M QCX that I built that I am using as a comparison radio to check measurements against.   So, I am not without a working model and I still have the 12 QCX's that I built for the Super Grabber that have been RETIRED by the new 12 QCX+'s  that are trudging on running 24/7 copying signals from all over the world.  
Have a nice trip to Vail .   I hope you can get there by Tuesday.   They got a lot more snow up there than we got here.  
Take care and have fun.   I will muddle along with this project and the 4 other ones I am working on.
73 Dave WA5DJJ
QRSS HF SUPER GRABBER  http://www.qsl.net/wa5djj/  2200M through 6M operating 24/7 from Las Cruces, New Mexico  Grid DM62ph


Shane Justice
 

Dear Dave,

Great to hear from you, and great that you have the equipment, and extensive knowledge of the QCX and QCX+! I did not realize you had built so many of these kits! 

I am in Vail, Arizona, about 25 miles East of Tucson. I graduated from NMSU back in 1980, so it would be fun to see Las Cruces again and make your acquaintance, if you ever want an eyeball QSO, or moral support with that problematic radio. BTW- I have a BSEE from NMSU.

I'm going to check out your SuperGrabber website- you must have quite the antenna farm!

73,
Shane
KE7TR




On Oct 28, 2020 at 21:30, David R. Hassall WA5DJJ <dhassall@...> wrote:

Dear Shane,
Thanks for the offer but I have just about the same stuff in my shop to attack a defenseless 4" circuit board and a bunch of parts.  I think I will be able to handle it as soon as I figure out what is going on with it.   The chase is half the fun of fixing it.   Today I replaced the LM7805 +5VDC regulator as it was drooping and wasn't putting out +5VDC.   The new one is at 5.02 VDC.  I also changed the two 10K resistors R1 and R2 with a pair of 1% 10K resistors.   That brought the voltage up to 1.98VDC but not to the 2.5 Volts I was expecting.   Looking at the circuit the only load for that voltage divider is the Quadrature Sampling Detector IC4 a surface mounted FST3253 of which I do not have.  So, I will work on getting a few and replace that one.  This is a case of it is the only thing left in the circuit that doesn't work.   There is also still another mystery lurking around IC7 and IC8 that is also causing problems.    So, It is just a wonder how this much stuff can be bad in just one kit.    I have a 40M QCX that I built that I am using as a comparison radio to check measurements against.   So, I am not without a working model and I still have the 12 QCX's that I built for the Super Grabber that have been RETIRED by the new 12 QCX+'s  that are trudging on running 24/7 copying signals from all over the world.  
Have a nice trip to Vail .   I hope you can get there by Tuesday.   They got a lot more snow up there than we got here.  
Take care and have fun.   I will muddle along with this project and the 4 other ones I am working on.
73 Dave WA5DJJ
QRSS HF SUPER GRABBER  http://www.qsl.net/wa5djj/  2200M through 6M operating 24/7 from Las Cruces, New Mexico  Grid DM62ph


Bob M.
 

Can you disconnect the secondary of T1 to check that 2.5V bias voltage? I don't know if the IC it feeds is passing that bias voltage to the circuitry to its right (on the schematic) but I suspect everything along that signal path is DC coupled so if you remove the chip, there won't be 2.5V present for the stuff after it. If you're going to remove that IC anyway, it's worth measuring the bias voltage with it out.

A product called Chip-Quik is amazing for removing SMT ICs. It alters the melting point of solder such that it stays molten long enough for you to grab a component and lift it right off with no damage. It's not cheap but you use so little of it, it's worth the price. They sell it in kits with some liquid flux included. You apply the flux, heat the connections, apply a tiny amount of Chip-Quik (it looks like solder) to all the joints, then lift the part off the board. In the case of an IC, flood the leads and pads with Chip-Quik, even if it's just one row at a time. Reheat it and lift the part off. Clean the board with solder wick or vacuum desoldering equipment then some isopropyl alcohol, and you've got a new clean place to install a new part.


Syd
 

The biases on C43 through C46 should all be very close to each other since that is where the I and Q pulses are integrated/filtered and all the filter circuits are identical.  So compare all 4 of the caps to resistor (R5, R6, R8 & R9) junctions with a DVM. If one these is off make sure there is a ground at the gnd end of the cap and then check the filter resistance value.  You could also ohm out each cap/res junction to ground just in case some is messing up the  paths from the Quad chip. Make sure the caps all have the same code.

Actually looking at the schematic you should be able to pretty accurately measure all the resistors in-circuit in all the OPAMPS! I have found out the hard way that the pots can give some strange problems if any one of them are at the shorted out end of range, so make sure to  measure them to make sure they are not at the end of range.
wt1v


ajparent1/KB1GMX
 

On Wed, Oct 28, 2020 at 09:29 PM, David R. Hassall WA5DJJ wrote:
  I also changed the two 10K resistors R1 and R2 with a pair of 1% 10K resistors.   That brought the voltage up to 1.98VDC but not to the 2.5 Volts I was expecting.   Looking at the circuit the only load for that voltage divider is the Quadrature Sampling Detector IC4 a surface mounted FST3253 of which I do not have. 
There lies the issue.  IF R1/R2 is not 2.5V then T1 and U4 are suspect OR ther eis a leaky path between
them and maybe ground.  C6 could have a weak (high resistance) short between it and ground.
That can be a result of the cooked traces and or board.

U4  Can have a input or output that in blown up (partial high leakage) due to ESD
at assembly time.   if the input votlages match the output something under or over
the board has caused a sneak path.

Also it can be as simple as ta resistor that was stuffed almost correctly save for one lead goes
though a VIA rather than a correct hole.


No matter what if Top of R2 is 5V (+-10%) then the middle must be half that (nominal 2.5V).
If that is not the case then stop there and find out why.  Going further down the amp just
amplifies the problem that starts there.

Allison
-------------------------------
Please reply on list so we can share.
No private email, it goes to a bit bucket due address harvesting


David R. Hassall WA5DJJ
 

Dear Allison,
Thank you for that analysis.   That is the same conclusion I came to.  I did lift the two leads from the voltage divider to the transformer T1 and the voltage at the junction between R1 and R2 was 2.5 volts.   when I connected the T1 leads back up It dropped to about 1.9 Volts.   The output voltage to the R5, R6, R8, and R9  was 1.63V on the top of all 4 of them.  So My conclusion is that the IC4 (FST3253) is bad.   So I have ordered some a few days ago.   I have handled Chips like this before so I should be able to replace this one easily.  
This QCX was given to me after ????? worked on it.   So I have been stamping down the trail of fixing the things that are wrong with it.   I have already done a lot of things already and there are still some more problems down the line.  
Take care and have fun.   I am using this one as a Troubleshooting training aid.   HI HI.
Dave WA5DJJ
SUPER GRABBER http://www.qsl.net/wa5djj/


James Daldry W4JED
 

Hi, Dave

Doncha love following another "tech"?

On my last job I spent 22 years as the "cleanup" tech - the tech of last resort - in the shop of last resort in a capital city. We did warranty service for over 70 brands of electronics - TV's, VCR's, camcorders, stereo receivers, CD and DVD players, wireless landline phones, commercial VCR's and cameras, etc. etc. If a customer from another shop got tired of waiting he would cry to the manufacturer, the manufacturer would call us, and you-know-who would get the job of fixing what the other guy buggered up, fixing it in a timely manner, and in a way that it stays home after it's returned to the customer. One thing I've learned is there are no perfect components, that any component can fail without being outside its ratings. I've seen many 1000 volt capacitors short out at 120 volts, and one at 6 volts in a battery powered portable radio.

My Softrock Sdr-lite kit arrived with a shorted '3253 chip. I guess they're a little fragible, since I've replaced hundreds of mosfets without breaking them.

73

Jim W4JED

On 11/3/20 12:41 AM, David R. Hassall WA5DJJ wrote:
Dear Allison,
Thank you for that analysis.   That is the same conclusion I came to.  I did lift the two leads from the voltage divider to the transformer T1 and the voltage at the junction between R1 and R2 was 2.5 volts.   when I connected the T1 leads back up It dropped to about 1.9 Volts.   The output voltage to the R5, R6, R8, and R9  was 1.63V on the top of all 4 of them.  So My conclusion is that the IC4 (FST3253) is bad.   So I have ordered some a few days ago.   I have handled Chips like this before so I should be able to replace this one easily.  
This QCX was given to me after ????? worked on it.   So I have been stamping down the trail of fixing the things that are wrong with it.   I have already done a lot of things already and there are still some more problems down the line.  
Take care and have fun.   I am using this one as a Troubleshooting training aid.   HI HI.
Dave WA5DJJ
SUPER GRABBER http://www.qsl.net/wa5djj/


Alan G4ZFQ
 

My Softrock Sdr-lite kit arrived with a shorted '3253 chip. I guess they're a little fragible,
Jim,

Until now I've refrained from saying that in all the time I've been in the Softrock group failed FST3253s have rarely been mentioned.
I guess maybe that could be because Softrocks with their SMD parts were more often built by those with a little more experience in troubleshooting rather than fewer failures?

73 Alan G4ZFQ


Syd
 

The bias voltages on C43-C46 all depend on filtering the I and Q outputs from IC4. Make sure the 2.5V input bias input to the IC is correct.  If you have a dual channel oscilloscope check that the signal from T1 at pins 7 and 9 are 180 degrees out of phase verifying T1 input winding is OK. Then check A and  B for the correct clocking signals. They make the signals filtered by C43 - C46.  Check that pins 1 & 15 on IC4 make a good ground. If all this is OK then check the RC filters C43-C46 and R5&6 and R8&9 for 2.6 V verifying the input to IC5 is OK. If not, make sure C43-46 make have good grounds. You can check that the codes on the caps are the same:  these caps have a very low fault probability.  If all this is OK, then I have a theory about one further check of the RC filters. Disconnect C43-C46 and the check the RC junctions with a scope, you should see the unfiltered sampling pulses from IC4 to the RC network, thereby proving IC4 is working, which is good since it is a SMD! If all that is OK then there must be a load on the RC filter network. The input of an opamp is very high (infinite), but a screwed up one can load the RC filter network messing up the bias!  If it comes to replacing IC4 or IC5 go for IC5 first as it is easier and  cheaper!
Just remember, if the bias on C43-C46 is screwed up, everything there after will be screwed up, so don't go any further than IC5!
73 wt1v


James Daldry W4JED
 

Hi, Alan

I mentioned the '3253 because I'm not the only one to have a failure. I've built kind of the big brother to the receiver half of the QCX - fst3253 front end, si5351 controlled by a atmega328p, 8 pole filter for wide ssb reception, narrow and wide audio filters. Most of it is built on perfboard, with the surface mount chips on little inch square pcb's to break out the connections. Of course, there were no part failures during the assembly process.

At the last shop where I worked the owner believed in rapid service for over the counter warranty service, to the extent that, if a store stock unit similar to a customer unit was in the shop, the store stock one became an "organ donor" for the new one. My first surface mount chip replacement was a servo chip for a Sanyo 9300 VHS VCR - a little one, only 16 pins on a side. I had to pull the customer chip off, pull the replacement off the stock VCR, install it in the customer set, and, when the new chip came in, install it in the stock unit. If you read your equipment warranty new parts are not required for warranty repair - they are only required if the repaired unit is to be sold as new.

Another fun part of this shop was that the owner didn't believe in modular repair unless the set was in warranty and you could get boards for it. So trouble shoot to the component was the name of the game. That included surface mount optoislolators on Pioneer plasma TV's. In assemblies with parts that number in the thousands you simply can't guess or shotgun. You replace whatever failed and whatever dominoes that also fell.

Back to the '3253. It was the first component that I've had fail before the unit had a chance to operate in several years. The only other failure I've had was an AD9850 that quit after a year or so - probably got static back through the output, since I didn't have a buffer amplifier on it. But I've never blown a PIC or an AVR in any of the projects I've built. In electronic service I've replaced at least a hundred embedded microcontrollers for anything from bad firmware to internal breakdown due to being installed too close to the CRT. I've replaced dozens of mosfets, anywhere from 20 amp 600 volt ones to 40673's in RCA and Zenith tuners. I've never zapped a 4000 series chip. So when a part fails on my bench it's memorable. And one was that 3253, which I was unable to positively determine what "failed" it. The only thing I know for sure is that the replacement is still working, and the original never worked.

Well, enough waa waa waa I am the greatest so don't you dare say anything waa waa waa. Maybe I should tell my imposter syndrome to shut up.

73

Jim W4JED

On 11/3/20 9:26 AM, Alan G4ZFQ wrote:
My Softrock Sdr-lite kit arrived with a shorted '3253 chip. I guess they're a little fragible,
Jim,

Until now I've refrained from saying that in all the time I've been in the Softrock group failed FST3253s have rarely been mentioned.
I guess maybe that could be because Softrocks with their SMD parts were more often built by those with a little more experience in troubleshooting rather than fewer failures?

73 Alan G4ZFQ





David R. Hassall WA5DJJ
 

Dear Syd,
I did replace IC5 hoping it was the cause of the low 2.5 voltage.  But it didn't change anything.   So I am almost 100% sure the problem is the FST3253 has some issue.   My parts just got here from Digikey, so I will be able to go back to work on this radio soon.   I will try to report my progress on here soon. 
Take care and have fun.   Thanks to everyone who sent me a suggestion.   I am now better prepared to do battle with this Dragon.
73 Dave WA5DJJ