I picked up this little Silvertone yesterday in LA. Don't have a model number and not sure of the year. Has the back and all the knobs and PB door. I did an internet search but couldn't find anything on it. Any input would be appreciated.

That set is a 1952/53 model. Sears used the same knobs and control door on several models. You need to show a chassis view to identify. Our family set was 21" console with the same knobs and control door. The chassis was made by Stewart-Warner. Your set might be a Pacific-Mercury. That was one of their suppliers on the west coast.

Thanks, I was able to find a silvertone set from 1953 with the same knobs so that helps identify the year. I'll need to get back home and take some decent pic of the chassis and measure the CRT.

Looked high and low for a model number. What I found was a catalog number 1299 and a chassis number. I measured the CRT from the outside cabinet glass diagonally it's 15 inches but it could be a 16 in CRT as there were very few 15" CRTs to look at in my testing book. There were no markings on the neck of the CRT. The end cap had a chunk missing but otherwise is intact. I tested the CRT and it has low emissions even after sitting for 20 minutes or so, infact the longer it sat the lower it went. I zapped it once and that helped momentarily but then it started to sink again. Anyone have a CRT that would work in this set that they are willing to part with? It's rectangular

Look for a number like 132.41000 or 569.32440200. (3 digits, decimal point, 5-8 more digits). Sears often used those types to identify sets, and a Sam's search may then find a match.



.

I found these numbers on a metal tag on the back of the chassis. 456.150-1,
Does that look like the model number? The chassis number is 47180.

I believe 456-150.1 is the chassis number and it's covered in Riders vol 14.

Also found in Sam's Photofact #230-10 from February 1954.

http://img27.imageshack.us/img27/263/img0069gj.jpg (http://imageshack.us/photo/my-images/27/img0069gj.jpg/)

Thanks I"ll check it out.

If someone would be so kind as to look at the info above and help me identify the CRT in this set I would appreicate it. I don't have any reference materials on hand. Also if some one has a good one I'm still looking for one.

Thanks

The Sams manual says 21MP4 (noting that some models may use 20HP4 or 20HP4A).

Phil Nelson

That set looks to me like a 17" set. Probably a 17HP4, or simular. The console pictured is a 20 or 21 inch model. They probably used that same chassis in 17, 20 and 21" models.

I'm going to take some better pics of this set and post them.

I was finally able to pull the chassis out of the Silvertone. For sure it's a 17" CRT. Too bad it's just about dead. Hopefully it won't be too difficult to find one. I took some pictures of the chassis and it looks to be fairly undisturbed although I can see where some work was done. I'll have to make some tough decisions on this one. Obviously not very valuable but I do like the looks of it and I'm sure it would be fun to watch.

That set looks to me like a 17" set. Probably a 17HP4, or simular. The console pictured is a 20 or 21 inch model. They probably used that same chassis in 17, 20 and 21" models.

Good Eye!

I think I found one it's a NOS from Bob. I think I will restore this set knowing that it will have a new CRT. Bob has some other large CRTs as well incase anyone is interested. If I had the gold I'd buy all the 16, 17, 18, and 19" CRTs.

I looked at the chassis and it looks like it might be one that I could replace the caps on. It would be my first.
what are the odds that it would work well if I just did that part? Can someone direct me to a copy of Riders 14 or Sam's Photofact #230-10 from February 1954? Neither one is available from the county library of San Bernardino or Los Angeles.



http://antiquetvguy.com/Web%20Pages/For%20Sale/Picture%20Tubes%20For%20Sale/Picture%20Tubes%20for%20Sale.html

Look for a number like 132.41000 or 569.32440200. (3 digits, decimal point, 5-8 more digits). Sears often used those types to identify sets, and a Sam's search may then find a match.



.

I looked on the ETF site but didn't find the Riders or Sam's listed there so I'm asking Sam's to do a search for me. Using their search engine it didn't find anything on either the model number or the chassis number. I did find a very dereriated label on the back that has the date 1950 on it. So We'll see what Sam's search comes up with. I believe the chassis number to be 47180 and the model number to be 456-150-1.

After looking at the bottom of the chassis and seeing only 15 or 20 caps there I'm really tempted to try and do this one myself. The component arrangement is very open...what could go wrong?...

According to the code date on the original CRT, it shows 1952, 47th week. It must be the original CRT. Made by National Union. Also looks like a 17HP4, which wasn't out in 1950. I never saw a Pacific Mercury set in the midwest.

Correction: 17HP4 30th week of 1952. 247 is the EIA code for National Union.

Well that nails it! It must be a 1952 or 1953, assuming that it was permissable at the time to use up remaining stock from the previous year. For sure it's not a 1950 as I was believing based on the label on the back. Perhaps at some point we'll find out if it's a Pacific Mercuray or not.

Thanks

Just got the bad news from Sams

"SAMS Technical Publishing was not able to locate the manual you requested in our database nor in our search with our partners. Sorry we could not assist you in this instance. Please check with us for future repair manual needs, we have access to over 230,000 repair manuals and are adding more every day."

Model 1299 and chassis 4561501 are covered in Sams 230-10.

https://www.samswebsite.com/en/photofact/search/index/page/1/samsid/230_10

:Model 1299 and chassis 4561501 are covered in Sams 230-10.

https://www.samswebsite.com/en/photofact/search/index/page/1/samsid/230_10

Riders #14 has a lot of coverage on that model. It shows several different variations of that chassis. Three different tuners. All the part numbers start with PMA or PMB. :scratch2:

Big Thanks! I'll order them both after I find out if Bob can deliver on the new CRT.

Bob was sick but he's better now and he says he's got the CRT boxed up and he'll send it out when he gets the check. The checks sent so now it's a waiting game. NOS it's gota be good.

Bob realy delivered on the CRT. Really well packaged and appears to be NOS as advertised. It tests "very good" on the meter.

I purchased the Sam's package on a download so I have that now. with the set turned on I did a quick visual inspection. With my Dim Bulb Tester plugged in I could see that two tubes weren't lighting up, the 1G3GT and the 6AV5 GA. I have some spares. The CRT is dark although I know it has some life left in it. I can hear the a raspy low volume humm. No sparks no smoke.

Here is a list of the capacitors. When I look at the list I see some of the voltages are not listed. Is the listing above it continued down until you get to a change? I don't see any listed as electrolitic does that mean there aren't any? I'm guessing that the part numbers won't be of much use since those parts aren't made anymore. Which caps should I replace? All of them? Is there one supplier that will have most or all of them? Thanks in advance.

C1 - C6 are the lytics. Any cap without a voltage spec is likely a ceramic or mica and (unless it is a mica in the deflection stages) should not need to be replaced. The ones that have a voltage ratings are either lytics or paper type and should be changed. Sam's always gives the first 'C' numbers to the lytic caps and you can tell the lytic from the paper because the capacitance value don't have any leading decimal points in the lytic values (Sam's also uses a different symbol for lytic caps than other types on their schematics which is helpful to know at times).

The ones that aren't lytics or papers (they usually have no voltage rating) and have values that don't contain decmal points are micas or ceramic and have their values listed in pico farads as opposed micro farads (like papers and lytics).

Thanks Tom, I'm guessing that C1A and C1B are in a silver can. Since the cap rating doesn't have a leading decimal point they are Lytics. Same with C2A,B,C. All five should be replace as they all show voltages. They are lytic also, and they are in a silver can to right ? Then C4-C6 Lytics.

C7 through C37 are probably ceramic or mica so those don't necessarily need to be replaced?

Since C38 has a leading decimal point It's not a Lytic. Same with C39. C40 doesn't have a leading decimal point so it would be a Lytic? Same with C41? Each of those shows a voltage rating so they should be replaced?

Thanks again.

If you've got room for it, I'd keep it. It looks fairly simple in design, and should be a good set with a little TLC and parts.

I've never had a set of my own of any kind that had a rectifier installed on the power transformer.

It's a set that I think I can work on. The layout is pretty clean not like a lot of sets that the components are so tightly packed in that they would be difficult to replace. It also looks like a set that would be fun to watch on a reqular basis. If all goes well this will be my first restoration. I don't have much is the way of equipment, just some basics. I'll see how far I get before I have to buy any or take it to an expert for help.

Rather than use the parts list to plan what to buy and replace, I recommend that you look at each part on the chassis itself to read its value and make your own list. That way, you will easily see what type each capacitor is, and you will get lots of hands-on practice with the parts as well. As you do this, also try to look for repairs done in the past-often, shinier solder blobs, parts that look cleaner or not matching most others, parts with wires twisted inline with the old ones, etc. The one item where this will not work is with any electrolytic capacitors that have cardboard covers over them. Their values are marked on the can itself underneath the cardboard.

Thanks Tom, I'm guessing that C1A and C1B are in a silver can. Since the cap rating doesn't have a leading decimal point they are Lytics. Same with C2A,B,C. All five should be replace as they all show voltages. They are lytic also, and they are in a silver can to right ? Then C4-C6 Lytics.

C7 through C37 are probably ceramic or mica so those don't necessarily need to be replaced?

Since C38 has a leading decimal point It's not a Lytic. Same with C39. C40 doesn't have a leading decimal point so it would be a Lytic? Same with C41? Each of those shows a voltage rating so they should be replaced?

Thanks again.

C1 and C2 are multi-section caps and are probably in metal cans.

C39 and C40 are NOT lytics they have too high of part numbers to be. They are likely to be ceramics or micas, and I'd not worry about those* unless after replacing the papers, lytics, bad tubes, and off tolerance resistors there are problems in the stages containing those parts.

*The three digit or less caps are almost always micas or ceramic and you need not worry about them, BUT the four digit and higher MAY be paper types with pico farad value labeling (ie 2200pF -> .0022uF/MFD). You will have to be wary as paper types with 4 digit pF labeling often are packed in mica style cases and are tough to tell apart from micas.

Which caps should I replace?
This article explains how to identify old caps and order replacements:

http://antiqueradio.org/recap.htm

As Chris noted, you need to look under the chassis in addition to looking at the parts list. The article (http://antiqueradio.org/recap.htm) shows photos of paper capacitors, electrolytics, micas, and so on.

If you have the Sams manual, that usually includes photographs of the chassis with arrows pointing to every component. That will help you match up what you see under the chassis with components in the parts list.

The basic drill is to replace electrolytics and paper caps (including plastic-coated paper caps). Leave mica and ceramic caps alone until you get the TV showing some signs of life.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

Thanks everyone. Is there one supplier that carries most of the caps?

http://justradios.com/ and http://www.mouser.com/ are two good ones.

Phil Nelson

Thanks again.Can you recommend an all around good tube tester that would cover most or all of the tubes I would find on sets pre 53 and might be available on ebay for a good price?

You'll do fine ! The Tech Gurus will be here to help you, & when you get it done, we'll ALL be happy for you !!

all around good tube testerSencore "Mighty Mite." I spent about $25 for mine. It's new enough that it didn't need any restoration (unlike many old testers you'll see for sale).

It's an inexpensive emission type tester, nothing fancy, but all I want from an everyday tester is a basic dud-or-not reading. Post-WWII TVs don't use the really old tube types (4- or 5-pin, whatever), so there's no advantage to getting a really old tester, which will need the same restoration as a radio or TV of the same vintage.

I also own older, fancier tube testers, but as collectibles, not working tools.

I imagine there are others comparable to a Mighty Mite (there was more than one version, by the way), but I just happen to own this one.

Phil Nelson

I have an "Accurate Instruments" model 257 Tester I use for most of my testing, it's very compact, new enough to be reliable and simple to use, I paid $10 for it at a swap meet but that was a long time ago.
They turn up on eBay from time to time, usually not for a lot of $$

$53:
http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&_trksid=p4340.l2557&hash=item3371d3ca30&item=220953037360&nma=true&pt=LH_DefaultDomain_0&rt=nc&si=8UILxFTqYUjnk%252FLIDh2jF0R6%252FFg%253D&orig_cvip=true&rt=nc

This one went for a whopping $173!:
http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&_trksid=p4340.l2557&hash=item27c1fcb99e&item=170758289822&nma=true&pt=LH_DefaultDomain_0&rt=nc&si=8UILxFTqYUjnk%252FLIDh2jF0R6%252FFg%253D&orig_cvip=true&rt=nc

$50ish seems to be the norm.

There's a nice Mighty Mite on eBay with five days to go:
http://www.ebay.com/itm/SENCORE-MIGHTY-MITE-III-TUBE-TESTER-TC130-CHARTS-AND-MANUAL-/270934950372?pt=Vintage_Electronics_R2&hash=item3f14fb41e4

I have a TV-7 and an EICO 667 - both are great to have. Ebay sure doesn't have any deals on TV-7s these days, but maybe you can find one through another source like a hamfest, or a craigslist ad. I got both my testers cheaply and use them often. The good thing about having a popular tester, is lots of service info and tube data can be found on the internet.

Thanks Phil, Eric, maxhifi, I found a EICO 667 on ebay 50 dollars with three days left. Just looking at it it doesn't look like it has very many different socket bases. Nothing on the Accurate Insterments model 257, found several Mighty Mites and a very pricy TV-7. The Mighty Mite is probably what I'm looking for. There are several different versions for sale on ebay right now and looks like manuals are available too. This one looks like a good one to go after..http://www.ebay.com/itm/SENCORE-MIGHTY-MITE-III-TUBE-TESTER-TC130-CHARTS-AND-MANUAL-/270934950372?pt=Vintage_Electronics_R2&hash=item3f14fb41e4&afsrc=1

Rather than use the parts list to plan what to buy and replace, I recommend that you look at each part on the chassis itself to read its value and make your own list. That way, you will easily see what type each capacitor is, and you will get lots of hands-on practice with the parts as well. As you do this, also try to look for repairs done in the past-often, shinier solder blobs, parts that look cleaner or not matching most others, parts with wires twisted inline with the old ones, etc. The one item where this will not work is with any electrolytic capacitors that have cardboard covers over them. Their values are marked on the can itself underneath the cardboard.

I'm having trouble identifying some of the components. I took Phil's suggestion and read through the antiqueradio website on identifying the caps and it helped a lot but I see a number of components that I can't identify. They look like ceramic covered coils, or resistors with coils on them. The check marks on the Sam's sheet are caps that I'm pretty sure I can identify.

The picture that came with my Sams folder isn't clear enough for me to identify all the items I'm looking at. I took some close ups of the area but that didn't help much. Maybe I'm taking the wrong approach. Should I just look for the caps that I know need to be replaced as described in the antiqueradio website? Following the information given in the article and looking at the photo I would say there are no caps that need to be replaced in the area shown. At the same time I think I can identify about eight caps in the picture.

In this photo, just north of the first photo, I can Identify four paper caps that should be replaced, right? The Pyramid being a lytic. What about the dark brown rectangular one in the upper right corner? Is that a plastic covered paper cap or a Mica?

I count three paper caps. Are you counting the electrolytic as a paper cap? While it needs to be replaced it's not classified as a paper capacitor.

The dark brown could be either a mica or paper. You need to look at the color code to determine that, or figure it out from the schematic and parts list. If the brand is Micamold you'll probably need to replace it even if it is mica. I'd leave it alone until you're sure.

The other things that look like coils on resistors are probably chokes.

In this photo, just north of the first photo, I can Identify four paper caps that should be replaced, right? The Pyramid being a lytic. What about the dark brown rectangular one in the upper right corner? Is that a plastic covered paper cap or a Mica?

Should I just look for the caps that I know need to be replaced as described in the antiqueradio website?Yes. Replace the obvious stuff first.

As John (and the article) noted, you can also use the value as a clue whether to replace. For instance, in your second photo, the whitish cap in the middle is marked .02, too big for a mica and too small for an electrolytic -- just right for a paper cap, so get it out of there.

I don't see anything to replace in the second photo. You're doing OK so far. Don't worry about the other components for the time being. The doughnut-ty shaped things may be peaking coils, and so on. You will have time to learn more about other components while waiting for your capacitor order to arrive.

Phil Nelson

In this photo, just north of the first photo, I can Identify four paper caps that should be replaced, right? The Pyramid being a lytic. What about the dark brown rectangular one in the upper right corner? Is that a plastic covered paper cap or a Mica?
As Phil and jeyurkon said, I think you are doing well with your progress. Three wax caps and a paper-covered electrolytic that should be replaced. The brown "domino" or "traffic light"-type one can probably be verified with a mixture of looking at its colored dots to see whether it is paper or mica, trying to find it in the Photofact picture, and tracing its ends to easily-identifiable parts nearby (does one end go to pin 6 of the tube socket in the upper-right corner? Check the schematic to see what cap is connected to that tube pin, etc.).

Thanks for all the feedback. I took another picture of the brown cap and matched it to the schematic. It's attached on one end to chassis ground and the other end to pin 8 of the Vertical output tube, 12BH7. By looking at this cap I wouldn't have thought it was a lytic but the schematic says it is.

It's definitely not an electrolytic. I think you might have identified the wrong tube.

Thanks for all the feedback. I took another picture of the brown cap and matched it to the schematic. It's attached on one end to chassis ground and the other end to pin 8 of the Vertical output tube, 12BH7. By looking at this cap I wouldn't have thought it was a lytic but the schematic says it is.

Perhaps you counted the pins wrong or you're looking at the wrong tube. When looking from underneath, pins are numbered clockwise starting at the key, or gap between the highest numbered pin and number 1.

That electrolytic is C5, a 100-mfd cap. Anything that size will be bigger than a paper cap. Look at page 9 in the Sams manual and find the circle with C5 inside. The arrow points to its location.

I seriously doubt that little square flat cap is anything other than a mica. All of the flat, plastic-coated paper caps that I've seen were rectangular rather than square.

Phil Nelson

Or perhaps counted the pins wrong, confusing Pins 7 & 2 with 8 & 3.:scratch2:

jr

Add: Phil beat me, so there are 2 votes for improper pin count.

HI:

If you need a brightener, and think it would help, I have several for series and parallel heater strings. I am assuming yours is a parallel heater set since the set has a big honkin' power transformer.

I had the wrong tube, It's attached at one end to ground and the other end to pin 7 of the 6AV6, it's C66, 1500MMf. Should I replace it?

HI:

If you need a brightener, and think it would help, I have several for series and parallel heater strings. I am assuming yours is a parallel heater set since the set has a big honkin' power transformer.

Thanks for the offer but I just got a NOS CRT a couple weeks ago.

If you haven't already done so, be sure and check that 270K resistor going to the wiper of the height control. It's the plate load resistor of the V.osc. It tends to go 'waay high in value because of being constantly hammered by a high level pulse during operation. It's a very common failure across all brands and vintages of sets. Well worth bookmarking.

I had the wrong tube, It's attached at one end to ground and the other end to pin 7 of the 6AV6, it's C66, 1500MMf. Should I replace it?

I'd leave it alone for now.

John

If you haven't already done so, be sure and check that 270K resistor going to the wiper of the height control. It's the plate load resistor of the V.osc. It tends to go 'waay high in value because of being constantly hammered by a high level pulse during operation. It's a very common failure across all brands and vintages of sets. Well worth bookmarking.

It looks like R65 on my schematic. ,red,violet,yellow. It tested 320-330k, +/- 10% at max should be 297K. I'll replace it. Thanks.

It's attached on one end to chassis ground and the other end to pin 8 of the Vertical output tube, 12BH7.

I had the wrong tube, It's attached at one end to ground and the other end to pin 7 of the 6AV6, it's C66, 1500MMf. Should I replace it?
This happens to all of us, and double-checking things is how we figure out the right answers and get better at it as we go along. Now that you know for sure what part it is, here is another tip: Look at its color markings, and see how the colors you find match up with its value (1500uuF, or 1500pF, or .0015uF) as listed in the manual, and compare them to the color codes for this type of capacitor. Do they match? If it appears to not match, try to figure out what is wrong. One or more colors may have faded, or maybe the markings are not as obvious as they could be. Comparing things like this can help later when you find items that really are hard to identify.

Thanks Chris. I'd like to take one more shot at identifying this cap. It doesn't have any color dots on it that I can make out. It's Solar and from what I've read on Phil's website it should come out right? Is it a paper cap wraped in plastic? I can't repost the picture but it's the same one as shown in entry #49.

Thanks Chris. I'd like to take one more shot at identifying this cap. It doesn't have any color dots on it that I can make out. It's Solar and from what I've read on Phil's website it should come out right? Is it a paper cap wraped in plastic? I can't repost the picture but it's the same one as shown in entry #49.

The dots would be painted on where you see those circles. They could have been cleaned off. I assume you checked both sides.

Now that you've identified the cap what does the parts list say about it? It should tell you whether it's paper or mica.

Hi jeyurkon, My parts list is shown in entry #28, page 2 of this thread (can't show it again here). It's cap #66. If the parts list is tells me what kind of cap it is I'm missing it. The back side has two dot circles but no color. Stamped into the cap is says what looks like "c100". I do see in the listing for the Aerovox part no. listing that the part number starts with "SI" if that means anything and that some others in that list start with "P".

From Phil's website:

"Note that two of these types—mica capacitors and flat molded paper capacitors—look similar. Both are flat, often with color coding dots to indicate the value. It is easy to tell them apart by checking the value. Mica capacitors have very small values, typically under .001 mfd. The values of molded paper capacitors will be larger, similar to other paper capacitors, such as .01 or .02 mfd."

refering to my parts list again on page 2, the first page under the "CAPACITORS" heading it says "Capacity values given in the ratings column are in mfd. for Electrolytic and Paper Capacitors, and in mmfd. for mica and ceramic capacitors."

When I read "1500" in the "cap. rating" columm I'm not sure if that's mfd. or mmfd.

The 1500 in the Sams parts list and schematic means MMFD. The header at the beginning of the capacitor section says, "Capacity values given in the rating column are in mfd. for electrolytic and paper capacitors, and in mmfd. for mica and ceramic capacitors."

That value, plus the square shape, tell me this is a mica cap, which I would not replace at this time.

Anything is possible, but in my experience, flat plastic-coated paper caps are rectangular, not square.

Many micas have colored dots, but some do not, and to add to the fun, more than one color coding scheme was used. It's possible that your cap once had colored dots, but the paint flaked off or faded.

I would replace the electrolytic and paper capacitors and worry about this one later.

Phil Nelson

I forgot that you were using a Sams. The factory manuals are sometimes more descriptive.

The Sprague part number is for a disk ceramic so it must not be too critical. I agree with Phil that this looks like a Mica capacitor.

"The 1500 in the Sams parts list and schematic means MMFD. The header at the beginning of the capacitor section says, "Capacity values given in the rating column are in mfd. for electrolytic and paper capacitors, and in mmfd. for mica and ceramic capacitors."

Ok I think I'm finally getting it. The fact that it's listed as "1500" tells me that it's a mica or ceramic.. if it was a molded paper cap the value would be higher. The small size (large number because of the listing method) tells me it's a mica or ceramic. For example C11 is probably a mica or ceramic it's listed as 1000.

I see where I could have also made the connection by looking at the schematic which shows C66 capacitor as a 1500 mmf, then looking at the chart and seeing that it was listed as 1500 would tell me it's a mica or ceramic. The reverse also being true that if I saw it on the schematic as a 1500 mmf and the parts list showed it as .00015 I could think it was a molded paper cap but that listing would give me doubt because of the small size..

Could I conclude that by looking at the schematic and the parts list I could make a list of the Caps I would want to replace and then go look over the chassis for confirmation?

You got it.

Phil Nelson

if I saw it on the schematic as a 1500 mmf and the parts list showed it as .00015 I could think it was a molded paper cap...
Just to clarify, though, 1500pF (picofarads) (called 1500mmF back then, micro-microfarads) is the same value as .0015 uF (microfarads). A value of .00015, though never written that way, would equal 150pF or 150mmF. The way I memorized these translations is that I remember there are six digits between a microfarad and a picofarad (or mmF). So, 001500 in this case. 1500 mmF or .0015 uF.

And, for decimal-place-challenged types like me, there are also handy charts like this one:

http://www.justradios.com/uFnFpF.html

Phil Nelson

Chris, After thinking I had it, I looked at that statement again last night and tried to match it with the cap chart, I could see that there was a mistake there. I did a little searching online and realized that there is a six zero difference as you pointed out between micro and micro micro, or pico not three. With a little practice today I should be able to get it streight. If not I can always fall back on a calculator like Phil offered. I have some good tools now and I think I can start puting my cap list together this week.

It's always reassureing to see info like this from Phil's website: (I'm reposting it here for my own quick reference)

"Capacitance values are expressed in units called farads, named after the British physicist Michael Faraday. The capacitors found in radios and TVs have values in tiny fractions of a farad.

A microfarad is one millionth of a farad, abbreviated as mfd, mf, µf, or uf.

A picofarad is one trillionth of a farad, abbreviated as pfd, pf, or µµf.

This website generally uses the abbreviation mfd for microfarads and pf for picofarads.

In vintage radios and TVs, capacitors typically have values in these ranges:
•Electrolytic: 1-200 mfd
•Paper: .001-1 mfd
•Ceramic and Mica: less than .001 mfd

Since a picofard is one trillionth of a microfarad, to convert from microfarads (mfd) to picofarads (pf), you move the decimal point six places to the right. For example:

.47 mfd = 470,000 pf

If you don't like doing such conversions in your head, you can look up the values in this handy chart from Justradios.com."

Thanks!

John

After matching the schematic with the components list I did a visual check of the chassis. As best I can determine these are the caps that need to be replaced. I couldn't find every capacitor. One or two I couldn't find on the schematic and a couple I couldn't find on the chassis but I think all the ones that need to be replaced will be replaced. I would appreciate any feed back.

Thanks

John

As you may already know, you can use 47uF capacitors to replace the 40s and 50s, 100uF to replace the 80uF, and 22uF for the 20s. Similar nearby values are usually good for the paper caps as well (.022 to replace .02 or .025, etc.).

I went to Mouser's website this morning and was able to find all the electrolytics by either making combination or just getting the right size. Looks like justradios will have the rest. I noticed that a repair was made at some point and a non electrolytic cap was used where the schematic called for an electrolytic. I wonder if the set ever worked after that...

Are there certain areas within the set that are likely to need to have resistors replaced, like in the high voltage area or around certain tubes. If so I can order them with the capacitors.

John

The resistors needing replacement are most often higher-value ones (perhaps 100,000 ohms and higher) in any circuit, as opposed to those in particular areas. They often go bad by becoming more than 20% higher in resistance than their original value. To some degree, you can test most resistors without disconnecting them, since the value you measure in-circuit would likely never be higher than the resistor value alone. 100K and higher are the yellow multiplier, green multiplier, and blue multiplier ones (the third stripe counting from the end where the stripes start). When I do tests, though, I test every resistor and also have found lower-value ones that have drifted higher.

Hi Chris, I was wondering about about how I should test the resistors. As I recall from my service days working on Hawk Missile radar at least one leg of the resistor needed to be removed to get an accurate reading. I think you've got it right, if the resistor being tested is one of highest valuse then it would be possible to get a reading on it without removing one leg. As one goes down the value scale probably some other resistors would begin to add values to the reading. If one of then high value resistors did test high the at that point it would be worth while to pull one leg and test it again.

People have different styles, but I normally do the basic recapping and then try out the TV before worrying about resistors. Nine times out of ten, the majority of resistors are OK and don't need replacement.

Resistors are generally more reliable than capacitors. Also, there are some circuits where the exact value wasn't that critical in the first place. In that case, even if a resistor's value has drifted to, say, 30% above its ideal value, the TV will work normally, and replacing the resistor won't noticeably improve anything.

One exception is a horizontal circuit that determines frequency, where exact values are important. If you want to check resistors before ordering caps, I'd check those around V19, the horizontal AFC/oscillator tube, especially R79 and R80.

I'd stay away from the RF and IF areas until after you finish recapping. In some of those, the lead dress -- exact location of every component and wire -- can be important. Messing with them for no good reason may force a realignment that wouldn't otherwise be necessary.

Old resistors typically go bad when they go open or their values drift high, so often what you're looking for is higher than normal test readings.

When you test a resistor without disconnecting it, then other components wired in parallel with it might make the total resistance value lower. They can't make it higher. That tells us two things:

1. If the tested value is high, then that resistor is probably high.

2. If the tested value is low, then that resistor might be low, normal, or even high, depending on what things are wired in parallel with it. To learn more, you can either disconnect the resistor or analyze the things wired in parallel and calculate the total resistance of all of them.

Most resistors had a manufacturing tolerance of +-20%, so the resistor is considered good if its value is 20% or less, above or below the ideal. If a specific resistor must be more precise, that's usually mentioned in the schematic ("5%" or whatever).

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

Phil, Sound like the right approach. I'll replace the caps first and see how it goes.

Thanks

Hi Chris, I was wondering about about how I should test the resistors. As I recall from my service days working on Hawk Missile radar...

Interesting and I certainly can identify with that training. I was trained at Redstone Arsenal, Huntsville, AL and that is the same procedure that we were taught. But I do agree with Phil and that is the tactic that I use.

BTW, where did you get your Hawk training? They trained Hawk at Redstone as well...

Yep! 1966. MOS 23T20, Hawk Missile Radar Repair, high power, pulsac and continuous wave radar. Redstone Arsenal, Huntsville, Al. 52 weeks total, 8 weeks basic electronics. Good to Know you! (P.S. never got sent back a week even once). Went to Miesau Germany from there. I was trained in the NiXi tube technology. I don't think they had transistors yet.

I wouldn't mind getting my paws on a good 17HP4 ;)