Hi All:

I am restoring a Sarton-27 Model 580, which is in very bad shape.

Resistor (R13), which is connected to the arm of (R2) the visoglo adjustment potentiometer, is burned beyond recognition. The value of this resistor is not indicated on the schematic. Physically, it looks to be a 3 or 5 watt resistor, value ?????.

Can anyone help?

Also, does anyone have the dail chord layout?

Gary

Perhaps I am looking at the wrong schematic, or maybe I'm just not looking hard enough, but the 580 schematic, as well as the 580X, does not show that a vis-o-glo was used with this radio. I also checked the model 27 schematic just to be sure (totally different radio, and amazing circuitry I might add), and no vis-o-glo was listed here, either. I assume that a vis-o-glo is the eye tube, as eye tubes were called vis-o-glo in later Sparton sets as well.

If you are absolutely sure that the model number that you give is the correct one, could someone have added the vis-o-glo?

Thomas

Thomas:

Thanks for the reply.

The reference to "visoglo" is just to the left of the AC receptacle. Also, in the chassis layout drawing there is a note pointing to the visoglo adjustment pot. I thought the eye tube and visoglo were one in the same, what do I know?.

I am sure this is a Model 580. Every circuit that I have traced matches the schematic and chassis layout exactly. However, I am a bit confused by the presence of the 6E5 eye tube, which is not shown on the schematic. Possibly an add-on?

Another problem, inductor (L7) is open. It is connceted to the bottom side of (L10) 2nd IF Xfmr. Do you know the characteristics of L7? Oddly enough, there is another L7, which is connected to pin 2 of the OSC tube. Perhaps this is a numbering error on the schematic.

This is the first radio I have worked on that has a separate RF amp, OSC and Detector not to mention 2 IF stages. I bet this will be a great set once I bring it back to life.

Gary

:Perhaps I am looking at the wrong schematic, or maybe I'm just not looking hard enough, but the 580 schematic, as well as the 580X, does not show that a vis-o-glo was used with this radio. I also checked the model 27 schematic just to be sure (totally different radio, and amazing circuitry I might add), and no vis-o-glo was listed here, either. I assume that a vis-o-glo is the eye tube, as eye tubes were called vis-o-glo in later Sparton sets as well.
:
:If you are absolutely sure that the model number that you give is the correct one, could someone have added the vis-o-glo?
:
:Thomas

You know.........that is very interesting. The vis-o-glo socket they show has only four pins! What kind of tube does your radio use? As for L7, is it wound intricately or is it wound simply? The intricate wound, which has a specific name that I am not sure of at this time (litz wound?), will look almost like it is braided. It will have a definite pattern. A simply wound coil will simply have wire wound around it like you would find thread on a spool of thread for sewing. If it is wound like a spool of thread, you can easily rewind it. Try to find the break and see if you can mend it. Antique Electronic Supply sells many sizes of RF chokes. The choke that is open in your radio does not serve any purpose in the RF section, so its frequency response does not have to be precise. It only serves to remove a certain portion of the high end from the audio signal. Usually this is done around 10 KC. You could simply purchase several or all of Antique Electronic Supply's RF chokes and try each one for the sound that you prefer. The optimum choke will remove that annoying high pitched ringing sound you hear on certain AM stations, but will not destroy the audio to any great degree.

Thomas

In the forties and fifties it was a fairly common "upgrade" to radios to add an "eye tube". Add on circuits were very common in the radio magazines. It was likely added later, or as a replacement for the original circuit/components by the sounds of the discussion.

Litz wire is a braid of individually insulated wire strands, and "litz wound", if not used as a descriptor for the wire used, applies loosely to winding the coil in a manner where there is minimal capacitive interaction between windings, and therefore minimal effects of capacitive reactance.

:You know.........that is very interesting. The vis-o-glo socket they show has only four pins! What kind of tube does your radio use? As for L7, is it wound intricately or is it wound simply? The intricate wound, which has a specific name that I am not sure of at this time (litz wound?), will look almost like it is braided. It will have a definite pattern. A simply wound coil will simply have wire wound around it like you would find thread on a spool of thread for sewing. If it is wound like a spool of thread, you can easily rewind it. Try to find the break and see if you can mend it. Antique Electronic Supply sells many sizes of RF chokes. The choke that is open in your radio does not serve any purpose in the RF section, so its frequency response does not have to be precise. It only serves to remove a certain portion of the high end from the audio signal. Usually this is done around 10 KC. You could simply purchase several or all of Antique Electronic Supply's RF chokes and try each one for the sound that you prefer. The optimum choke will remove that annoying high pitched ringing sound you hear on certain AM stations, but will not destroy the audio to any great degree.
:
:Thomas

This one uses a 6E5.

Gary

:You know.........that is very interesting. The vis-o-glo socket they show has only four pins! What kind of tube does your radio use? As for L7, is it wound intricately or is it wound simply? The intricate wound, which has a specific name that I am not sure of at this time (litz wound?), will look almost like it is braided. It will have a definite pattern. A simply wound coil will simply have wire wound around it like you would find thread on a spool of thread for sewing. If it is wound like a spool of thread, you can easily rewind it. Try to find the break and see if you can mend it. Antique Electronic Supply sells many sizes of RF chokes. The choke that is open in your radio does not serve any purpose in the RF section, so its frequency response does not have to be precise. It only serves to remove a certain portion of the high end from the audio signal. Usually this is done around 10 KC. You could simply purchase several or all of Antique Electronic Supply's RF chokes and try each one for the sound that you prefer. The optimum choke will remove that annoying high pitched ringing sound you hear on certain AM stations, but will not destroy the audio to any great degree.
:
:Thomas

Does the 6E5 plug into a 6 pin socket that is wired directly into the chassis or does the 6 pin socket have a wire that leads to a 4 pin socket...like an extension...? I just find it interesting as to how they represent the eye tube socket as a 4 pin. Don't know why I'm asking this, either, as it has little to do with your original question, but I am curious.

T.

Thomas:

The tube plugs into a 6 pin socket that is wired directly to the chassis. It must have been an after-market modificaiton. Do you know what the original visoglo tube was?

Another question, the screen bypass capacitor and the cathode bypass capacitor for the 1st RF amp (C10) are shown as 1uf on the schematic. Is this right? I think they are .1 uf. I also checked the Model 104 schematic, which shows them as .1 uf.

Out of curiosity, do you know the purpose of C7, 8uf cap shown connected to pin 2 of the 1st RF amp? Is it a coupling cap?

Gary

:Does the 6E5 plug into a 6 pin socket that is wired directly into the chassis or does the 6 pin socket have a wire that leads to a 4 pin socket...like an extension...? I just find it interesting as to how they represent the eye tube socket as a 4 pin. Don't know why I'm asking this, either, as it has little to do with your original question, but I am curious.
:
:T.

The 1. MFD caps you see are the correct values. This is an appropriate value for a screen grid filter condenser, though .1 or as low as .05 would work well in most cases, too. The value of this condenser is not too critical as long as it is not too small. It keeps the voltage at the screens from fluctuating. If they fluctuated, spurrious oscillations would develop.

As for the 8 MFD condenser, that one is interesting. It is obviously a bypass condenser, passing RF from the plate of the 1st tube to the antenna grid of the 2nd tube. That is a huge value, though, and furthermore it almost makes the various RF band bypass coils unnecessary. I will have to look at the diagram more closely when I am more awake (just got home from work...it's 8 AM).

As for the eye tube, I think they either omitted certain pins of the socket that didn't have wires directly coupled to them, or they misdrew the socket. I don't think that there are any four pin eye tubes.

Thomas

Thomas

Thomas:

That 8uf capacitor is indeed a strange one. I'm not sure if I can even describe it to you. But here goes, it consitts of a couple of small disc about .5 inches in diameter with lugs for soldering. The discs appear to be seperated by a dialectric and riveted together. Have you ever seen anything like this? If you are curious, I can take a picture of it and email it to you if you.

Gary

:The 1. MFD caps you see are the correct values. This is an appropriate value for a screen grid filter condenser, though .1 or as low as .05 would work well in most cases, too. The value of this condenser is not too critical as long as it is not too small. It keeps the voltage at the screens from fluctuating. If they fluctuated, spurrious oscillations would develop.
:
:As for the 8 MFD condenser, that one is interesting. It is obviously a bypass condenser, passing RF from the plate of the 1st tube to the antenna grid of the 2nd tube. That is a huge value, though, and furthermore it almost makes the various RF band bypass coils unnecessary. I will have to look at the diagram more closely when I am more awake (just got home from work...it's 8 AM).
:
:As for the eye tube, I think they either omitted certain pins of the socket that didn't have wires directly coupled to them, or they misdrew the socket. I don't think that there are any four pin eye tubes.
:
:Thomas
:
:Thomas

Gary,
Original viso-glo tube was a Sparton VG-1. These are very scarce and probably the reason the radio was rewired to accept the 6E5.

WOW! VERY COOL! That tube isn't even listed in any of my tube manuals. I can see how it would only have four pins. If you put the 1 meg resistor inside the tube and tie the cathode to one of the filament leads, you will only need four pins.

T.D.

:Gary,
:Original viso-glo tube was a Sparton VG-1. These are very scarce and probably the reason the radio was rewired to accept the 6E5.

Hi Gary,
Sparton models 104,105,135 have vis-o-glo circuit electrically similar to your 27/580.
Value for R13 is 3k. Also, R11 (resistor connected to red pin) is 1Meg/.25W.
Since this is a Canadian radio, Ed Kraushar might give you some better info.
Hope this helps.
BR,
Dave