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 Post subject: Re: New Amp Pick-up
PostPosted: Feb Sun 10, 2019 5:43 pm 
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Location: Keystone Heights, FL, USA
Dan, you cannot hook the meter up like that. It is providing a direct short circuit to the A voltage.

The ammeter should be inserted in series in the circuit. That is, the meter is placed in place of one of the wires going to the tube (blue or yellow, does not matter).

In other words, remove the blue wire completely. Then clip the red meter lead to where the blue wire was on the tube socket. That way the current flows through the meter to be measured, the same way your water meter measures water usage.

You also need to get some real Fluke meter leads and quit using those home made leads.

PS - Consider that if the regulator is bad you may have 13 volts at the A terminals; bad for the tube.

Jeff


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 Post subject: Re: New Amp Pick-up
PostPosted: Feb Sun 10, 2019 7:29 pm 
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Jeff - Leads aren't homemade. Wired in series made little difference, .014 instead of .013. Replaced regulator (read previous post) and everything else in circuit except pot.

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 Post subject: Re: New Amp Pick-up
PostPosted: Feb Sun 10, 2019 7:45 pm 
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Location: Latham NY
You might have blown a fuse on the Fluke.


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 Post subject: Re: New Amp Pick-up
PostPosted: Feb Sun 10, 2019 8:18 pm 
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atwaterkent1 wrote:
Jeff - Leads aren't homemade. Wired in series made little difference, .014 instead of .013. Replaced regulator (read previous post) and everything else in circuit except pot.

Sorry, Dan, but leads with screwed on banana plugs are homemade, no matter who made them.

As mentioned, the fuse may be blown in the meter.

Disconnect tube and meter form K101, turn it on. What is voltage at A terminals? Does it adjust up and down with the pot?

Jeff


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 Post subject: Re: New Amp Pick-up
PostPosted: Feb Sun 10, 2019 9:35 pm 
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Fuse is fine. Voltage goes up and down with the pot.

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 Post subject: Re: New Amp Pick-up
PostPosted: Feb Sun 10, 2019 11:52 pm 
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Location: Keystone Heights, FL, USA
That sounds good. If you set the voltage at 5 and then wire in the tube does the tube light? Sounds to me like the K101 is working as it should. Measure the voltage with the tube hooked up (red lead in volts socket, not the A socket). Just wondering.


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 Post subject: Re: New Amp Pick-up
PostPosted: Feb Mon 11, 2019 1:38 am 
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The voltage has always been there Jeff, the lack of amperage is the problem.

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 Post subject: Re: New Amp Pick-up
PostPosted: Feb Mon 11, 2019 2:57 am 
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atwaterkent1 wrote:
The voltage has always been there Jeff, the lack of amperage is the problem.
Well, all the parts except the transformer have been swapped still no joy.

>>Transformer has a bad joint where the wire enters the bobbin...

I won't suggest swapping the transformer, but it is possible to indirectly determine if the winding can deliver the current..

Use ohms law to determine a fixed resistor of a value that is determined by the maximum current the "A" circuits is supposed to deliver, connect that across the AC windings. That leaves the bridge and the regulator out of the test. Once the resistor is connected, with no load (DC side) and the voltage output turned to low. Measure the ac voltage across that resistor. Do the same for the working K101, if the "bum" k101 has a lower voltage there is the problem. If not, I do not know what is going on???

If a 1 ohm resistor of sufficient wattage is added in series to that load resistor the current can be estimated by measuring the voltage drop across the 1 ohm resistor. That would make an additional confirmation of the current that winding can deliver. These are all AC voltages... There won't be any risk to the AMP portion of the DVM or the Simpson using a "sense" resistor. Again, apply ohms law to determine the current from the voltage. If that current is 3 amps and the transformer is not hot and the voltage is the (what, 10 volts?) then we are chasing a ghost. Still, could be a crappy external connection, cold joint?

If you have a substitute 12 volt 3 amp or better filament transformer sub that for the "A" supply winding into the K101 rectifier/regulator filter. If that don't give the wimpy circuit some welly, then lash-up the battery out of the model "A"...

Chas

(You need more junque in your junk box).....

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 Post subject: Re: New Amp Pick-up
PostPosted: Feb Mon 11, 2019 4:59 pm 
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Your meter reads 13 millivolts, it appears you have that tube as the load for the supply.

If the regulator IC is working properly you should be able to adjust the voltage using the pot.

I believe the regulator IC has an over current protection of around 1 Amp so if you over load it, it just shuts off. Your tube could be a 1 Amp 01. Since your Fluke meter has a 10 Amp scale you could find out what the Amp draw is using another power supply, as I am guessing it is in shutdown. Don't exceed about 5 volts on the tube filament as those tip off brass bas tubes are scarce.

The kit puts out about 12 volts from the bridge rectifier and the IC is an adjustable regulator so you can set it for 6 volts for the 01-A sets or lower for the V99 sets.

There are non adjustable versions of that IC such as 7805, 5 volt 7812, 12 volt as well as negative voltage regulators. The IC costs about $1.00 from parts dealers and the entire circuit has about 4 components.

Jim


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 Post subject: Re: New Amp Pick-up
PostPosted: Feb Mon 11, 2019 6:29 pm 
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Location: Keystone Heights, FL, USA
atwaterkent1 wrote:
The voltage has always been there Jeff, the lack of amperage is the problem.

How are you measuring the amps? Like in the picture? If so, that is wrong.

I asked this, "set the voltage at 5 and then wire in the tube does the tube light? ..... Measure the voltage with the tube hooked up (red lead in volts socket, not the A socket)."

The result would be helpful in determining what is going on.


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 Post subject: Re: New Amp Pick-up
PostPosted: Feb Tue 12, 2019 12:02 am 
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Amperage checks the same, in series with the tube or not, .013 amps. The B/E can't put out the .265 amps needed to light the tube (I hooked the tube up to another K101 and it lit the tube with the tube drawing that amount of current.)

Jim - As I posted earlier, its an 01A tube.

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 Post subject: Re: New Amp Pick-up
PostPosted: Feb Thu 14, 2019 2:49 am 
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NEVER ASSUME ... I made the mistake of assuming the wiring was correct to begin with and that a part was bad. I bought is used so I assumed it had been used before successfully. Wiring was wrong. Filament voltage working fine now, only problem is 90v connection puts out only 76v. 135v connection checks good and unmarked connection between 90 and 135v checks 100v. All other B voltages correct. I'll replace the diodes in that area and that should do it, hopefully.

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