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Author Topic: re: the ft-101e i am working on  (Read 5487 times)
KE3WD
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Posts: 5694




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« Reply #15 on: July 12, 2013, 07:51:44 AM »

I also when up line and checked the voltage there.  There is nothing,  0 volts on the 600vdc line.  I checked the vom's manual it can handle up to 1,000 volts ac or dc providing I have the right high voltage prob.  But I am not testing anything like an old tv that needs the high voltage prob. 

I do hope that the, "1,000 volts" is a misprint or typo on your part.  The High Voltage Probe would be easily capable of measuring 25 times that level or more.  1KV (1,000V) wouldn't accelerate electrons enough to make a CRT TV screen happen very well at all.  25KV, on the other hand, is in the ballpark. 

You also say, "zero volts on the 600vdc line" but don't mention what the voltmeter setting is when you report that.  And since we've already been through that as regards the dual 247V line, are you perhaps again mistaking the meter's report of an overvolt situation as being "zero volts"? 

Just in the way of example, if your meter selection reads 600V, and you are  trying to read a voltage on a testpoint that the schematic identifies as "600V" well, the realworld voltage might be a little higher than 600 and the meter is thus once again in the situtation where it must report an overvoltage situation that you may be misreading as no voltage at all.  A dangerous situation, too, as you may be thinking that certain parts of that circuit can't bite you at the time. 

Be careful in there. 

And, it may be time to pick up another DMM that has higher voltage ranges on it, suitable for boat anchor work.  The imported meters can represent very good value and won't break the bank.  Tenma.  Good stuff.  But even the lowcost meters sold by Harbor Freight can do the job as far as troubleshooting goes. 


73
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KC7BYP
Member

Posts: 51




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« Reply #16 on: July 12, 2013, 01:52:32 PM »

The 1000 volts max ac or dc is out of the vom's owners manual without a high voltage probe.  I already posted that I wasn't getting the correct readings because I didn't have the range set right on this new digital vom.  I though the vom set the range automatically.  I have to reset the range every time the vom turns its self off. This is my 1st time doing any serious troubleshooting with this new vom.

I also when up line and checked the voltage there.  There is nothing,  0 volts on the 600vdc line.  I checked the vom's manual it can handle up to 1,000 volts ac or dc providing I have the right high voltage prob.  But I am not testing anything like an old tv that needs the high voltage prob. 

I do hope that the, "1,000 volts" is a misprint or typo on your part.  The High Voltage Probe would be easily capable of measuring 25 times that level or more.  1KV (1,000V) wouldn't accelerate electrons enough to make a CRT TV screen happen very well at all.  25KV, on the other hand, is in the ballpark. 

You also say, "zero volts on the 600vdc line" but don't mention what the voltmeter setting is when you report that.  And since we've already been through that as regards the dual 247V line, are you perhaps again mistaking the meter's report of an overvolt situation as being "zero volts"? 

Just in the way of example, if your meter selection reads 600V, and you are  trying to read a voltage on a testpoint that the schematic identifies as "600V" well, the realworld voltage might be a little higher than 600 and the meter is thus once again in the situtation where it must report an overvoltage situation that you may be misreading as no voltage at all.  A dangerous situation, too, as you may be thinking that certain parts of that circuit can't bite you at the time. 

Be careful in there. 

And, it may be time to pick up another DMM that has higher voltage ranges on it, suitable for boat anchor work.  The imported meters can represent very good value and won't break the bank.  Tenma.  Good stuff.  But even the lowcost meters sold by Harbor Freight can do the job as far as troubleshooting goes. 


73
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GW3OQK
Member

Posts: 133




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« Reply #17 on: July 13, 2013, 03:17:59 AM »

Thanks 'BYP. Its a most difficult set to work on but if you can measure the HT at one point, and find it doesn't arrive at the next point, join them together with thin wire. Or, if you cant measure continuity on your VOM (AVO8?) do the same, at least that's what I would do.

There are quite a few mods suggested on the web. I have modified mine a fair bit after repairing it. Next I need to make it do full break-in on CW.
Andrew

 

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KC4MOP
Member

Posts: 728




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« Reply #18 on: July 13, 2013, 03:28:58 AM »

I hope you did not spend big money on that new VOM...Is that a Digital type? Most of those POS's will not like high voltage D.C. I have popped many of those $29.99 eBay type DMM's pretty close to what you are trying to measure in the FT 101. What they say in their specs about MAX voltage capability is BS!
Don't forget to switch reading A.C volts and D.C. The meter dos not automatically detect the difference AC/DC. It might auto-range.
You're getting closer to success.
fred
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KC7BYP
Member

Posts: 51




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« Reply #19 on: July 13, 2013, 04:24:50 AM »

I don't remember were I got it or how much it was.  Yes it is a digital vom.  I do remember that I got it because it can handle up to 1,000 volts ac or dc without a high voltage prob.   It also has a 10 amp max port and it can measure diodes and capacitors.  It also comes with a  temperature prob and a frequency prob. But it can't measure more then about 23khz top end max.

Steve

I hope you did not spend big money on that new VOM...Is that a Digital type? Most of those POS's will not like high voltage D.C. I have popped many of those $29.99 eBay type DMM's pretty close to what you are trying to measure in the FT 101. What they say in their specs about MAX voltage capability is BS!
Don't forget to switch reading A.C volts and D.C. The meter dos not automatically detect the difference AC/DC. It might auto-range.
You're getting closer to success.
fred
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KC4MOP
Member

Posts: 728




Ignore
« Reply #20 on: July 13, 2013, 07:49:45 AM »

I don't remember were I got it or how much it was.  Yes it is a digital vom.  I do remember that I got it because it can handle up to 1,000 volts ac or dc without a high voltage prob.   It also has a 10 amp max port and it can measure diodes and capacitors.  It also comes with a  temperature prob and a frequency prob. But it can't measure more then about 23khz top end max.

Steve

I hope you did not spend big money on that new VOM...Is that a Digital type? Most of those POS's will not like high voltage D.C. I have popped many of those $29.99 eBay type DMM's pretty close to what you are trying to measure in the FT 101. What they say in their specs about MAX voltage capability is BS!
Don't forget to switch reading A.C volts and D.C. The meter dos not automatically detect the difference AC/DC. It might auto-range.
You're getting closer to success.
fred
The 10 AMP max port is for measuring D.C. current...AC current is best done with an AMPROBE.
OK, then we're searching for an open circuit and the missing 600v coming out of the Rectifier PCB.

http://www.students.ncl.ac.uk/zoltan.derzsi/img/ft_101/ft101psu.png
I hope the link works. Are the diodes in their proper positions? I can not see why you have 240-0-240 on the secondary and no 600vdc .
Fred
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KC7BYP
Member

Posts: 51




Ignore
« Reply #21 on: July 13, 2013, 03:24:00 PM »

I am getting 525vdc on the 600v line.  It drops to around 493vdc on transmit.  I see a momentary jump in the swr/power meter (about a 1/4th of a watt)  then back to zero when I keyup.

I don't remember were I got it or how much it was.  Yes it is a digital vom.  I do remember that I got it because it can handle up to 1,000 volts ac or dc without a high voltage prob.   It also has a 10 amp max port and it can measure diodes and capacitors.  It also comes with a  temperature prob and a frequency prob. But it can't measure more then about 23khz top end max.

Steve

I hope you did not spend big money on that new VOM...Is that a Digital type? Most of those POS's will not like high voltage D.C. I have popped many of those $29.99 eBay type DMM's pretty close to what you are trying to measure in the FT 101. What they say in their specs about MAX voltage capability is BS!
Don't forget to switch reading A.C volts and D.C. The meter dos not automatically detect the difference AC/DC. It might auto-range.
You're getting closer to success.
fred
The 10 AMP max port is for measuring D.C. current...AC current is best done with an AMPROBE.
OK, then we're searching for an open circuit and the missing 600v coming out of the Rectifier PCB.

http://www.students.ncl.ac.uk/zoltan.derzsi/img/ft_101/ft101psu.png
I hope the link works. Are the diodes in their proper positions? I can not see why you have 240-0-240 on the secondary and no 600vdc .
Fred
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KC4MOP
Member

Posts: 728




Ignore
« Reply #22 on: July 14, 2013, 03:17:09 AM »

What changed from your last couple of replies? You are now getting HV to the tubes? There has always been HV? Sounds like multiple problems in the TX. The 600 volts dropping that much is not goodness. Did you replace the finals and the driver tube? It's close to repairing a color TV from the 70's... Always shotgun/replace the horizontal output Tube and Damper, for starters.
But for your rig, it would be a good fresh start for 100W.
We'll keep plugging away at it. Hopefully it's the tubes.
Fred
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