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 Post subject: Looking for help with Hickok 533
PostPosted: Feb Sun 25, 2018 5:26 am 
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Joined: Feb Sun 25, 2018 5:19 am
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I just purchased non-working Hickok 533 (not A)
The problem I have is that I don't get ground on cathode pin of at least 2 sockets I've tested today. All other pins respond with somewhat proper voltages against case ground. Bias pot adjust from 0 to neg 44v. Plate voltage is around 170v, etc., Only against the case of the tester. No reading against cathode pin 8 on Octal and Miniature sockets. I have schematics and have trouble following this craziness back from socket cathode pin. I do not see any grounding points on the schematic.
Does anyone know where cathode pin gets it's supply within the tester?
I don't see chassis grounded. Does it get referenced through the switches bodies? Very confusing.


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 Post subject: Re: Looking for help with Hickok 533
PostPosted: Feb Sun 25, 2018 9:55 am 
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Greetings to Grindfix and the Forum:

Regarding your questions: The cathode of the tube under test does not return to ground according to the theory of operation of the Hickok mutual conductance circuit. As far as I know, the Hickok frame is grounded only incidentally.... and should not be involved in the test circuit directly.

Please take a look at: http://www.museumofbroadcasting.org/Hickok.html

Here you will find an excellent explanation of how the circuit works. Once you have this in mind, you can proceed to trouble-shoot your 533. As a general rule, all measurements are made with respect to the cathode pin of a tube socket.... not to the chassis. Which pin this is depends on the setting of the cathode selector switch.

Good Luck,

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Jim T.
KB6GM


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 Post subject: Re: Looking for help with Hickok 533
PostPosted: Feb Mon 26, 2018 1:17 am 
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Is the tester not working? What are the problems?


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 Post subject: Re: Looking for help with Hickok 533
PostPosted: Feb Mon 26, 2018 1:59 am 
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Joined: Apr Wed 13, 2016 1:23 am
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Location: Independence, MO
Does your tube tester power on? Tubes light up? A little more information might help. In the meantime

http://tone-lizard.com/basic-hickok-troubleshooting/

Jim


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 Post subject: Re: Looking for help with Hickok 533
PostPosted: Feb Mon 26, 2018 3:15 am 
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rja2907@comcast.net wrote:
Does your tube tester power on? Tubes light up? A little more information might help. In the meantime

http://tone-lizard.com/basic-hickok-troubleshooting/

Jim



Jim,

Tester powers up and filament voltage is present on correct pins.

That troubleshooting article is based on 6v6 tube settings.
I put switches in positions according to test data. I get no Signal, Plate or Screen voltages against cathode pin 8 of octal tube socket but I get proper responses against tester chassis. I know from previous reply that tester chassis is not intentionally grounded. I tried to follow the schematic to see where cathode string comes from and got lost in switches. I don't know if all switch sections are shown from front view and which direction they need to be "dialed" to tube data to follow the signal path.
I bet at some point, someone tested shorted tube and resistor popped somewhere.
Could it be R27 1meg at the cathode switch? Awfully high value for cathode circuit though.

Thanks for your help, guys!

Dmitriy


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 Post subject: Re: Looking for help with Hickok 533
PostPosted: Feb Mon 26, 2018 4:14 am 
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Jthorusen wrote:
Greetings to Grindfix and the Forum:

Regarding your questions: The cathode of the tube under test does not return to ground according to the theory of operation of the Hickok mutual conductance circuit. As far as I know, the Hickok frame is grounded only incidentally.... and should not be involved in the test circuit directly.

Please take a look at: http://www.museumofbroadcasting.org/Hickok.html

Here you will find an excellent explanation of how the circuit works. Once you have this in mind, you can proceed to trouble-shoot your 533. As a general rule, all measurements are made with respect to the cathode pin of a tube socket.... not to the chassis. Which pin this is depends on the setting of the cathode selector switch.

Good Luck,


Jim,

Thanks for reference to the article. I think I need to test English dual pot.
I got this tester in pretty poor condition. It seems it was sitting in wet moldy basement for years. I didn't even try to power it up and went straight to cleaning.
First I used compressed air to blow off loose junk, then I sprayed entire underside with fast evaporating brake parts cleaner and followed with Deox-it of all switches. A lot of dirt, mold, grime and oxidation came out and unit looks much better now .
I let it sit for about 24 hrs before powering up.
After all this was done I read on AK forum that cleaning of the switches is not recommended. Too late now but I can't see how it can hurt. I use Deox-it on all audio gear rotary switches of same design and have never experienced any issues with wafer material contamination.
Bias rheostat wiper was bent, so I took shaft out and straightened it. Rheostat tests perfect now. Line adjust rheostat tests and works correctly and I can set line voltage without any fluctuations. I haven't tested English dual pot thinking that closed design carbon bed pot is least of my worries. Will have to re-visit that.
I will update my findings tomorrow.

Thank you for your help,
Dmitriy


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 Post subject: Re: Looking for help with Hickok 533
PostPosted: Feb Mon 26, 2018 8:11 am 
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Greetings to Dmitriy and the Forum:

I think you will find that the "English" pots are wirewound with a custom taper. Calibration of the "English" scale is done by unsoldering a mechanical joint between the two "cans" containing the potentiometer "innards" and rotating one pot with respect to the other. When calibration is established, the cases are soldered together again to retain the relationship.

These pots have custom tapers and are not available from any source as far as I know. If they are bad, your only recourse is to find someone who is parting out a 533 series tube tester with good pots.... not something that happens very frequently.

Hopefully, your "English" pot stack is in good shape. Treat it carefully.

Regards,

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Jim T.
KB6GM


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 Post subject: Re: Looking for help with Hickok 533
PostPosted: Feb Mon 26, 2018 10:03 pm 
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Are you pressing the test button P4 when taking the measurements?


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 Post subject: Re: Looking for help with Hickok 533
PostPosted: Mar Thu 01, 2018 7:12 pm 
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Yes, I take all measurements with P4 pressed.
English pot spec is 150ohm. Mine measures 94ohm each rheostat.
I found 2 open resistors. Both of them unfortunately are precision spool type. 150 ohm and 109 ohm.
Replaced with standard resistors just to test for voltages without load. I now get Plate and Screen voltages against cathode pin 8 (6v6 test data)
No 5vac Signal on pin 5 at all.
Bias voltage is good against tester case but not against cathode pin 8.

Any suggestions?

Thanks,
Dmitriy


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 Post subject: Re: Looking for help with Hickok 533
PostPosted: Mar Fri 02, 2018 1:49 am 
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Joined: Apr Wed 13, 2016 1:23 am
Posts: 110
Location: Independence, MO
R29--R30 would be where I would look. Do you have the Cal. procedure?


Attachments:
calib533(a).pdf [255.23 KiB]
Downloaded 11 times
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 Post subject: Re: Looking for help with Hickok 533
PostPosted: Mar Fri 02, 2018 2:11 am 
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The schematic I have has up-to R27. I haven't found last 2 resistors on my tester.
What schema are you using that shows R29-R30?

I have cal procedure but no Known Good 6L6 tube to do it with


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 Post subject: Re: Looking for help with Hickok 533
PostPosted: Mar Fri 02, 2018 4:15 am 
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Joined: Apr Wed 13, 2016 1:23 am
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Location: Independence, MO
Grindfix,
Opps, :oops: I was looking at what I thought was the 533 on the bama sight, :shock: but when I checked my file it does not show 29-or 30. Very sorry---I'm not sure where else to try.

Jim


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 Post subject: Re: Looking for help with Hickok 533
PostPosted: Mar Fri 02, 2018 5:04 am 
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Could someone explain how to "dial" those switches on the schematic?
I can't figure it out. It's also possible that there was more then one version of the tester, which would explain why switches on schema do not seem to match the ones on the tester. But without knowing which way they all need to be turned from POS-1, I might be looking at the wrong path altogether.


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 Post subject: Re: Looking for help with Hickok 533
PostPosted: Mar Fri 02, 2018 9:33 am 
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Greetings to Grindfix and the Forum:

You asked:

Quote:
Could someone explain how to "dial" those switches on the schematic?


The answer is: not easily.

The Hickok scheme for the switch settings is very clever (and unfortunately, very convoluted) logic. Hickok wanted to be sure that the tube tester could not be damaged by inadvertently dialing two different functions to the same tube pin... for example, plate and cathode or grid and screen. Therefore, whenever a function (for example plate) is set to a specific pin, all other functions (grid, screen, cathode, suppressor, plate and filaments) are excluded from that pin. Although some here on the ARF will tell you this is a no-no, I routinely set the filament settings (two letters) and the filament voltage and then plug the tube in while I am setting the rest of the selectors. This saves time in testing... the tube can be warming up while you are setting everything else up. Because of the Hickok logic system, this is a perfectly acceptable procedure. It is NOT acceptable for many cheaper testers that do not have the Hickok lockout system incorporated in their design. (Note: it is not acceptable for the Hickok compactron adapter CA-4, either.... it will happily short things out when rotating its selector switches, so it should be unplugged from the tester while setting up.)

Unfortunately, the price for this degree of idiot-proofing is quite a bit of added complexity in the switch logic.

I can say this: The numbers for plate, screen, grid, suppressor and cathode correspond directly to the socket pin numbers. Zero on any switch position is no connection, EXCEPT for the plate and grid switches, where zero connects the internal circuitry to the jacks for plate and grid caps, respectively.

The filament wiring is more complex because of the fact that you have to make two connections before the filament can be heated, so Hickok went with letters instead of pin numbers instead. JR is a common filament setup; I believe that it is 3 and 4 on a 7-pin miniature socket, 4 and 5 on a 9-pin miniature socket and 2 and 7 on an octal socket.

The best way to deal with the Hickok switch matrix is to make numerous copies of the schematic. Using colored pens, draw the actual route through the switches for each function for a particular tube setup. If that gets too busy on one schematic, draw each function on a separate schematic. If you need to check out more than one setup, make more lines on another copy of the schematic. If you are interested only in the cathode circuit as seems applicable to your difficulty, draw only that in an obvious color.

Once you have thus eliminated the switches, you can then see where in the matrix the signal is disappearing (if indeed the problem is there) and what to do about it.

It ain't easy. I have a 534B that I would just as soon eliminate the multi-meter function from to improve reliability. I have never done so, because I have been too lazy to put in the work necessary to figure it out.

Good Luck,

_________________
Jim T.
KB6GM


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 Post subject: Re: Looking for help with Hickok 533
PostPosted: Mar Fri 02, 2018 5:40 pm 
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No one really answered my question but I think I got it figured out.
Please, correct me if I'm wrong. Here is what I came up with:

Front sections of all switches on schematic dial clockwise
Rear sections of all switches on schematic dial counterclockwise
Tube sockets on schematic are displayed from bottom view, so they are numbered clockwise

If that is correct -- I should be able to "dial" all switches to, lets say 6V6 tube data and follow the madness of the circuit to it's source.
I believe that I have switch connectivity problem because I was getting Plate and Screen voltages against cathode couple of days ago.
Today, I do not. instead, I got Signal voltage on pin 5 against pin 8 today. This never happened before. I'm not sure it is correct because it responds to Bias pot and I was getting around 5vac with Bias pot at 100% and around 1.2vac at specified tube data bias position of 13.

I'll be busy following the schematic and checking continuity through switches this weekend. Meanwhile, if anyone has any comments or hints, please share.

Dmitriy


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 Post subject: Re: Looking for help with Hickok 533
PostPosted: Mar Sat 03, 2018 4:36 pm 
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Thank you Dmitry for your investigation and posting of findings.

This might not be pertinent because it is something I discovered working on my
533A model but it is not mentioned throughout the calibration procedure in the manual except in initial set-up. I found it is important to consistently reset the line voltage every time anything is changed. If you turn one of the soldered pots you must re-set the line voltage. If you adjust, say, the bias pot setting, you must again reset the line voltage.

I'll be following this thread with interest.


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 Post subject: Re: Looking for help with Hickok 533
PostPosted: Mar Sat 03, 2018 5:03 pm 
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the lines are confusing, I print out extra pages and use high lighters to trace the circuits I'm working on

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 Post subject: Re: Looking for help with Hickok 533
PostPosted: Mar Sat 03, 2018 9:09 pm 
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Joe,

I've printed schematic on 6 page tile and taped it together.
Couldn't spare time to get into it yet.
I think my only option is when everyone is asleep.
I'm in Columbus too!
New Albany area.

Dmitriy


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 Post subject: Re: Looking for help with Hickok 533
PostPosted: Mar Sun 04, 2018 4:56 am 
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Joined: Apr Wed 13, 2016 1:23 am
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Location: Independence, MO
Grindfix,

What does a tube do when you test it?? Will the meter react at all? Seems like you have all the voltages present ( except 5v ).
I'm just curious, I did not see where a test was made---or I could have missed it. Let us know- :)
Jim


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 Post subject: Re: Looking for help with Hickok 533
PostPosted: Mar Sun 04, 2018 5:16 am 
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Jim,

I can't do a tube test.
Several of precision spool resistors are currently replaced with standard resistors just to provide the path through the circuit. I will unwind them and repair once I find the open in cathode circuit.
Meter reacts and I can adjust line voltage.

Partial success today. I found and repaired broken wire at tube sockets, supplying cathodes of all tubes. Now I have pin 3 and pin 4 voltages against cathode pin 8 on 6v6 tube setup.
Bias (pin 5) is still against chassis only.
VAC Signal (pin 5) against chassis only and changes from 0 to about 7vac with bias pot increase.

I was wrong on switch dialing.
Rear sections are printed mirrored on the schematic, so they would need to be dialed clockwise too.

I drew a connection line that goes through all switches dialed for 6v6 and will go through all points of switches to see where signal breaks tomorrow.

Stay tuned as I'm not loosing hope yet.

Dmitriy


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