I seldom post to this board, (last time in 2009), but I read it every so often as there are a lot of questions answered already that come up for me. I'll be honest, I'm always intimidated because as a woman, I feel that I am invading the male place. Please forgive me, but I can find no information on the particular questions that I have.

O.K. on to the topic...
I have recently acquired a wonderful old Supreme Model 89D tabletop tube tester. It was in very dirty condition and I have been slowly cleaning it up. I love the skill and pride that went into it. The Bakelite and the old oak case are just gorgeous! The unit is relatively intact, but some 'critter' was able to get into the chassis and chew a couple of components and some insulation from wires. If it was a rodent, it had to be very tiny. Not sure, since no droppings or urine stains are anywhere to be found whatsoever. My dilemma is that one capacitor in particular, a Solar Sealdtite, has been all but obliterated. I have visited Steve Johnson's site and have downloaded the schematic for this tester. What I have found is that the capacitor values are very vague on the schematic. None of them exactly match the caps in my unit. I have also read that Supreme made a lot of changes in production that were not always updated. What I am confused with is that there is no real voltage ratings shown on the schematic. The cap in question is a .01uf between two rotary switch contacts. The schematic says - .01/.1. (lower left corner meter circuit section on schematic). All of the capacitors are shown this way except for the grid cap on the 01A tube, which is another confusing issue as well.

First question: What is the voltage rating and value for the .01 capacitor on the schematic? I am guessing it to be 100 volts (?) judging by the size, but not certain, since there is very little of it left. Is it even supposed to be a .01uf???

2. What is the correct value and voltage rating for the capacitor tied to the grid and plate circuit of the 01A tube? Note "C" says that it was changed to a 40uf from a 50 or 5.0 (?), or is it 4.0 uf? The schematic is very hard to read and leaves a lot to be desired in terms of legible writing! (Some illustrator needed a good penmanship class! ) Note "C" says that it is supposed to be substituted for an electrolytic although the picture does not show it as being polarized???

There are only four capacitors that I have found in this tester and nothing matches what is on the schematic at all!

If someone could tell me what all of the CORRECT values and voltage ratings as well as the direction of polarity of the cap tied to the grid and plate circuit, if in fact it is supposed to be an electrolytic. None of the caps in my tester appear to be electrolytic. This unit "appears" to be all intact with no hacking done by anyone except the little critter that was inside it once.

Caps in my tester are:
2x - .5uf Solar Sealdtite @250v (love the look of those vintage light blue Solar caps!)
1x - a large, very old, wax covered Sprague "600 Line" .5uf @ 600v (gorgeous graphics on it BTW!)
and 1 little, obliterated Solar Sealdtite, of which not I am sure what this value and voltage rating is supposed to be!

The schematic is on Steve Johnson's site if you need to see it. Thanks to Steve for making whatever information is available on these testers available!

I have a couple of other questions but do not want to get in trouble for posting these, since they are different items of the same tester.
Any help would be greatly appreciated. Thanks so much!

Hopefully this is of some small help.

The schematic is also in Riders Volume 7. Unfortunately, I only have the freebie PDF's floating around, and they're not any more legible than Steve's. (The schematic in the 89D tech PDF is the most legible of the bunch IMO, it at least has the electrolytic polarity marked on it.)

Another point, at least to question 2. The capacitor is shown on Figure #10 of the tech analysis PDF from Steve's site. Its listed as a 0.5uF there. However, the voltage across it looks to me to be closer to 500V (350VAC * 1.414 = VPeak, once rectified by the 01A acting as a diode)

As always, YMMV, I don't have any experience with this particular device...

David

You're correct on the first 3 caps

The unmarked one in my unit has an ink stamp of .077uf @ 400v. You could just use a .1uf or make up one using a .068uf and a .01uf.

Thanks for the response.

I have downloaded this .pdf from Steve's site, but what is confusing is that on Figure number 10, it shows the same capacitor as 0.5, but if you look on the full schematic page at the end, it shows the same cap which looks to me like it says 40MFD, if my eyes are seeing it correctly. The big 600 volt Sprague that is in my set is a 0.5mfd. The one in my unit is not an electrolytic that I can tell. There are absolutely no polarity markings on it. This is what I don't understand about the schematic substitute that lists "C" modification as an electrolytic.

Maybe someone else can chime in that has seen more of these testers and knows what to look for. I do intend to re-stuff the big Sprague, but I want to make sure to get the correct cap for this unit, as well as the other ones.

Thanks ChuckA.

So is the one that the critter chewed to bits the .077uf @ 400v that I need? That Solar Sealdtite in between those two contacts on the rotary switch is very small in comparison to the two 0.5uf @250 v caps that are in there. That is why I was guessing it to be maybe a 50 or 100 volt max. capacitor. It is one fourth the size.

Yes the .077uf is connected to the rotary switch sections.

Thanks so much for the help!! Now I will be able to get this little gem closer to operation again! I will not be able to reuse the chewed little Solar for re-stuffing, but will try to find something suitable that will appear vintage. I know that there are much more modern mutual conductance testers out there, but these beautiful testers are worth being brought back as the wonderful historic pieces equipment that they are, IMHO.