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It is possible that someone who had this tube tester previously cleaned the controls and switches with the wrong type of cleaner; it may have left residue that is causing the shorts lamp to come on. The only thing to do is clean everything with a 'no-residue' cleaner, then use Deoxit or some other high quality cleaner/lube. Also, there may be a resistor that is placed across the shorts neon lamp; this may have increased in value.
Johnnysan-
:Assuming the A model can measure leakage in megohms, does it show any?
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:Looking at the on-line manuals for the 539B and 539C and my printed manual for the 539A, it appears that only the 539C has the ability to measure heater-cathode leakage with the Gm meter. My meter does not move at all during shorts tests. Thanks much for the response, I really enjoy your book and use it often as a reference. John.
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::Assuming the A model can measure leakage in megohms, does it show any?
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:It is possible that someone who had this tube tester previously cleaned the controls and switches with the wrong type of cleaner; it may have left residue that is causing the shorts lamp to come on. The only thing to do is clean everything with a 'no-residue' cleaner, then use Deoxit or some other high quality cleaner/lube. Also, there may be a resistor that is placed across the shorts neon lamp; this may have increased in value.
:Johnnysan-
Thanks for the reply. I see no sign that this thing was cleaned or lubed by anybody before me--no sign of a residue at all, but that's a good thought. There is a 1 meg resistor across the neon lamp, but I guess I really don't know that much about how this neon lamp works. How could a resistor with elevated value cause it to glow without a test tube even being inserted? thanks again, John
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::It is possible that someone who had this tube tester previously cleaned the controls and switches with the wrong type of cleaner; it may have left residue that is causing the shorts lamp to come on. The only thing to do is clean everything with a 'no-residue' cleaner, then use Deoxit or some other high quality cleaner/lube. Also, there may be a resistor that is placed across the shorts neon lamp; this may have increased in value.
::Johnnysan-
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:Thanks for the reply. I see no sign that this thing was cleaned or lubed by anybody before me--no sign of a residue at all, but that's a good thought. There is a 1 meg resistor across the neon lamp, but I guess I really don't know that much about how this neon lamp works. How could a resistor with elevated value cause it to glow without a test tube even being inserted? thanks again, John
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:::Well, I found this Hickok 539A in an antique store, and I'm trying to get it working. I have replaced the two e-caps and the "paper" cap and I have replaced the 83 rectifier with the solid state replacement suggested by Alan Douglas. The dial lamp comes on and the two small meters work, but the shorts lamp lights in all switch positions (with intensity that increases wtih each position) even without a tube inserted. I've looked for any visable shorts, etc. Has anyone run into this before? Any ideas? I'm stumped. thanks much, John.
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::It is possible that someone who had this tube tester previously cleaned the controls and switches with the wrong type of cleaner; it may have left residue that is causing the shorts lamp to come on. The only thing to do is clean everything with a 'no-residue' cleaner, then use Deoxit or some other high quality cleaner/lube. Also, there may be a resistor that is placed across the shorts neon lamp; this may have increased in value.
::Johnnysan-
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:Thanks for the reply. I see no sign that this thing was cleaned or lubed by anybody before me--no sign of a residue at all, but that's a good thought. There is a 1 meg resistor across the neon lamp, but I guess I really don't know that much about how this neon lamp works. How could a resistor with elevated value cause it to glow without a test tube even being inserted? thanks again, John
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Ohhhhh Tayyyyyy ! ( a . . la . . Little Rascals) . . . . well lets just see if we can get that little "perky puppulating" again. In its operation, the gases ionize and the flow path thru an ionized gas plasma is certainly more conductive and efficient than the 5Y3. The lower voltage drop and the higher current /power capability was a great boon in efficiency and performance to those transmitters. |
> > > Hickok Thumbnail Schematic:< < <  |
:Replace it, it will cost a nickel See what happens. :::It is possible that someone who had this tube tester previously cleaned the controls and switches with the wrong type of cleaner; it may have left residue that is causing the shorts lamp to come on. The only thing to do is clean everything with a 'no-residue' cleaner, then use Deoxit or some other high quality cleaner/lube. Also, there may be a resistor that is placed across the shorts neon lamp; this may have increased in value.
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::::Well, I found this Hickok 539A in an antique store, and I'm trying to get it working. I have replaced the two e-caps and the "paper" cap and I have replaced the 83 rectifier with the solid state replacement suggested by Alan Douglas. The dial lamp comes on and the two small meters work, but the shorts lamp lights in all switch positions (with intensity that increases wtih each position) even without a tube inserted. I've looked for any visable shorts, etc. Has anyone run into this before? Any ideas? I'm stumped. thanks much, John.
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:::Johnnysan-
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::Thanks for the reply. I see no sign that this thing was cleaned or lubed by anybody before me--no sign of a residue at all, but that's a good thought. There is a 1 meg resistor across the neon lamp, but I guess I really don't know that much about how this neon lamp works. How could a resistor with elevated value cause it to glow without a test tube even being inserted? thanks again, John
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John
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:Sir John. . . . . .
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:Ohhhhh Tayyyyyy !
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:( a . . la . . Little Rascals) . . . . well lets just see if we can get that little "perky puppulating" again.
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:If you have found NO inter contactive contaminants on the toobie sockets or switches . . .particularly, that (S-18)cluster of 12 switch contacts that is progressively inter-switching in the myriad of combinations of potential adjunct electrodes within a tube .
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:Now then lets go thru a logical evaluation of the unit.
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:What I . . . REALLY . . . REALLY . . . think, is that your replacement of the 83 with the SS replacements has produced the unwelcomed effect of shifting that units higher voltage power supply section into a low impedance power supply, too much so, in fact.
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:You say . . . . WHUT ? ? ? ?
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:I say . . . . then let me 'splains it to you.
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:The low voltage portion of the tester unit is using a hard vacuum recifier . . .a 5Y3 . . . so that type of tube is going to have the least efficiency of rectification with it experiencing decades of volts in losses/ voltage drop in passing from the plate to filament /cathode.
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:A next tube to consider would the be the soft /cold gas OZ4 rectfier with its nitrogen/argon gas fill.
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: In its operation, the gases ionize and the flow path thru an ionized gas plasma is certainly more conductive and efficient than the 5Y3.
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:(Mind you that the OZ4 is NOT used in this unit, and usually its eminant domain is to be found within auto radios , but it was the next tube that I had in mind in the degree of efficiency of rectifiers.)
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:Now we take your 83 with its mercury vapor fill and the free mercury in the tube that is used for supplicating the mercury vapor. That combination is even MORE conductive in its ionized plasma path and its efficient than the latter TWO types of tubes just covered.
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:The mercury vapor rectifier really came into good use for radio transmitters and their need for needing both high levels of voltages and current.
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: The lower voltage drop and the higher current /power capability was a great boon in efficiency and performance to those transmitters.
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:And now . . . AND NOW . . . we get to your use of two 1N4007 and series in line surge limiting resistors.
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:Now in that case you are going to get a mere ~.7 Volt drop . . . . O.K., I'll say that again . . . into your other ear . . . a MERE ~.7 Volt drop . . . . . . in their conversion efficiency . . . or on upwards to a volt or so if you are REALLY pushing them up towards providing their max current limits.
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:NOW . . . lets see how that relates to your current situation.
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:The lower voltage power supply section (provided by the 5Y3 circuitry)is almost solely relegated to the bucolic task of mere bias provision.
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:The higher voltage power supply section (a . .la . .83) is taking on more of the demanding task of the plate and screen supplies . . . definitely more power related . . wouldn't you say ?
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:Looking at the 5Y3 output voltage merely being acouple of millamps of current drain that supply should pretty well hold its output voltage level.
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:Different story on the 83 supply, as that might be handling the minimal plate supply, current requirements with the testing of a 6SQ7
:on a first test or the NEXT tube in line to be tested could likely be a 6L6 where the supply might then be subjected to its most demanding current supply and the coincidental "pulling" down of that B+ supply voltage under that loading effect.
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:Now,its YET another story . . . . . . when using your SS replacements, the inherent developed B+ is going to be QUITE a bit larger just by virtue of that miniscule voltage drop of the silicon diodes, and no significant drop from those ~ 10 ohm metal film current/surge
:limiting resistors.
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:(The only place where I saw that conversion . . was in a photo that MIGHT have been of Sir Alan Douglas' (Esq.) origin . . or else someone that had tried his technique and illustrated it . . . and it was showing a gutted bakelite tube base shell with two vertically mounted 10 ohm blue metal 1-2 watt film resistors and two adjunct 1N40xx diodes all set down within the shell.)
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:Plussssssss now there will be MINIMAL pull down on the developed power supply voltage when you try retesting that 6SQ7 and then putting in the current hog demands of a following 6L6 test .
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:That is what is meant by a low impedance power supply characteristic.
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:Soooo effectively we now have more voltage than the equipment had in its original design. That would go along with having the transconductance testing being in error unless recalibrated with the higher voltage . . . . . or . . .more preferably, changing the 10 ohm resistors upwards to progressively higher values that are eventually selected to have the supply putting out the SAME voltage that the 83 did when it was testing its most demanding condition . . . . testing that 6L6.
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:This all ties in to the quiescent conditon . . . no tube being transconductance tested . . . but supply voltage from the 83 powr supply putting out more than typical and hitting your supply to your neon lamp circuitry with more than normal and it responding in kind with its indications.
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:Procedure 1:
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:(Of a sequence of exploratory tests)
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:Put your 83 back in the set and I would assume that it is still good anyhow . . . as mine in a Military TV-7 has served me from
:1964 til now . . . flawlessly . . . for any YEAR that I might pull it out of storage from the attic and use it.
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:( Ahhhhhhh that invigorating aroma . . . nothing like the rancid smell of 140 degree F fungicidal varnish in the morning ! )
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:Warm up the set with the 83 and see if that "Freon" shorts lamp is NOW acting squirrelly ?
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:Also, test a 6L6 or some other real power tube and take its transconductance reading.
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:Standing by . . . for your feedback . . . in order to see which ONE of two hunna' and 'lebenteen branches in my troubleshooting flow chart is to be reverted to next.
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:Info 1:
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:The Schema thumbnail is attached just below and you can see only the relevant circuitry for the " shorts " testing.
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:Denote the typical series current limiting resistor (Pale Orange) R35 (Brown-Red-Yellow) assuring us that the lamp doesn't incandesce and start burning up the electrodes from the tips downwards.
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:Then, there is the voltage scaling resistor (Pink) R36 (Brown Red-Yellow) just above it, which can tailor /compress/stretch the incoming voltage level /to the striking voltage threshold of the neon lamp.
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:Tell us what resistance they measure, and note that they are isolated by the circuitry to their left except for ONE wire on the right terminal of the neon lamp socket which really needs to be LIFTED to avoid any "phantom" in circuitry resistance loop .
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:(That specific wire is the one which is just above the "SHORTS LAMP" label.)
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:ALSO on the ( YELLOW) marked up C3- C2 capacitors . . . . NO DC leakage tolerated on them, when being subjected to a +100 VDC test supply voltage.
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:Now if you don't get the present Neon short lamp ambiguity condition, with the 83 toobie installed , we're half- ways home already.
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:73's de Edd
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::Replace it, it will cost a nickel See what happens.
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:::::Well, I found this Hickok 539A in an antique store, and I'm trying to get it working. I have replaced the two e-caps and the "paper" cap and I have replaced the 83 rectifier with the solid state replacement suggested by Alan Douglas. The dial lamp comes on and the two small meters work, but the shorts lamp lights in all switch positions (with intensity that increases wtih each position) even without a tube inserted. I've looked for any visable shorts, etc. Has anyone run into this before? Any ideas? I'm stumped. thanks much, John.
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::::It is possible that someone who had this tube tester previously cleaned the controls and switches with the wrong type of cleaner; it may have left residue that is causing the shorts lamp to come on. The only thing to do is clean everything with a 'no-residue' cleaner, then use Deoxit or some other high quality cleaner/lube. Also, there may be a resistor that is placed across the shorts neon lamp; this may have increased in value.
::::Johnnysan-
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:::Thanks for the reply. I see no sign that this thing was cleaned or lubed by anybody before me--no sign of a residue at all, but that's a good thought. There is a 1 meg resistor across the neon lamp, but I guess I really don't know that much about how this neon lamp works. How could a resistor with elevated value cause it to glow without a test tube even being inserted? thanks again, John
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Bear in mind that the "short" is not actually zero resistance; it's whatever Hickok decided was a good threshold value for leakage.
Is the problem related to summer humidity?
You could try lowering the 1 meg resistor across the lamp, to see if you're just on the threshold.
:The 83 only glows when the Gm test button is pushed. In standby, the 83 caries no current. It should have no effect on the shorts problem.
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:Bear in mind that the "short" is not actually zero resistance; it's whatever Hickok decided was a good threshold value for leakage.
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:Is the problem related to summer humidity?
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:You could try lowering the 1 meg resistor across the lamp, to see if you're just on the threshold.
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:Just a thought about this. Could it be there is some conductive crud on the tube socket connections? Take an old tooth brush, and clean all the backs of the sockets with a little rubbing alcohol. Let dry of course before testing again.
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:I suspect conductive residue on the selector switches. You could eliminate the sockets as the cause by disconnecting them temporarily. Could be the wiring to the sockets too.
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John
:You can dry leaving it in a dry area, or carefully apply a heat gun to the sockets and switches.
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In continuing the quest, and seeing that the BAMA schematic available to me was for the C series, and none floating around for the A series |
:I live in northern Colorado. The whole state is a dry area. Humidity hardly ever goes much above 20%. thanks though,
:John
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::You can dry leaving it in a dry area, or carefully apply a heat gun to the sockets and switches.
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:Sir John. . . . . .
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:In continuing the quest, and seeing that the BAMA schematic available to me was for the C series, and none floating around for the A series
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:I pose some questions:
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:Since you have the unit and can confirm . . .
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:Does yours have the configuration of the switch to the left of the rotary shorts switch being a rotoary switch or a vertically moved toggle switch, which offers the subminuature tubes and mintature tubes at one position , with the other tubes being the "other tubes" positions option.
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:A photo of another units configuration shows a rotary switch being used, but with its markings being undiscernable to me.
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:As for the shorts switch, as best as I can make it out is for it having 1-5 short test positions and a 6th final . . . Tube Test position?
:No problem making it out on the B-C models as it must have ~12 positions but with the right half of the switch positions dedicated to its use as an ohmmeter with read out on the meter . . . of course . . . that is not true with your set.
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:You mentioned the resistor which shunts across the Neon lamp as being 1 meg on your unit or R36 / 120k (Pink) on my "C" schema.
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:What is the value of your units series current limiting resistor R35 / 120k (Pale Blue) on my "C" schema.
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:Also . . . are you finding the R45 (Pale Blue) cal pot on your unit ? it might only be a small 1 inch unit and possibly remoted off a bit from the "shorts" site.
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:Also if you have the miniature/other tubes switch do you find there being a difference in the "degree of shorting" as indicated by the neon lamps intensity, when it is being toggled between those 2 positions ?
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:After inspecting the schematic for my Hickok TV7 for its scheme of design in ITS shorts testing feature, they are using raw AC out of the 170 VAC winding of the power transformer circuitry and then feeding it into a 2 resistor voltage divider and then coupling AC out thru a .1 ufd isolation capacitor. That AC voltage then provides a convoluted path thru the SHORTS switching possibilities that then individually end up across the SHORTS lamp readout circitry.
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:No reason to think that they would deviate from their prior ciruit design in your A version set . . . . ( excluding the aditional use of the meter as an ohmmeter readout in the C series of units, but that is merely additional to your conventonal SHORTS testing feature.)
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:You can confirm this to be true by the probable need to unscrew the dust cap from above the NE-51 lamp to get better eyeball contact with that lamp . . . might even clean its glass envelope, while in there . . . then you perform a shorts test and confirm that BOTH electrodes of that NE-51 are illuminating. Now, should they have opted to test with DC, only ONE electrode would be illuminating on that lamp.
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:Waiting to hear back with the info on the questions from you, or additionally, for someone else to offer an " A " schematic version of the 539.
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:Supposedly ?. . . . an "A" version photo of a 539's faceplate . . . etched on it . . . but not with the toggle switch mentioned.
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::I live in northern Colorado. The whole state is a dry area. Humidity hardly ever goes much above 20%. thanks though,
::John
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:::You can dry leaving it in a dry area, or carefully apply a heat gun to the sockets and switches.
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