Dove right in! Help with RCA 21-D-8628

[Electronic M]

The Voltohmist is a VTVM (vacuum tube volt meter)...it's solid state equivalent is a VOM (volt ohm meter). Modern measurement devices are DMMs which use LCDs to display a digital value for voltage, current, resistance etc...All these will work about as good as each other in nearly all cases. Seeing as you're a beginner I'd recommend a DMM as they are much simpler to use, easier to read, and don't require calibration every time you turn them on. Also if you blow up your DMM a replacement can be had as quick as a trip to your local hardware, auto parts store, Walmart etc.

Originally Posted by Electronic M

The Voltohmist is a VTVM (vacuum tube volt meter)...it's solid state equivalent is a VOM (volt ohm meter). Modern measurement devices are DMMs which use LCDs to display a digital value for voltage, current, resistance etc...All these will work about as good as each other in nearly all cases. Seeing as you're a beginner I'd recommend a DMM as they are much simpler to use, easier to read, and don't require calibration every time you turn them on. Also if you blow up your DMM a replacement can be had as quick as a trip to your local hardware, auto parts store, Walmart etc.

I have a Klein DMM that is actually pretty decent. My issue is that I never seem to get the same readings unless I set it to capacitance, which I think I can trust. It doesn't measure leakage as you said. Ohm readings are the wonky thing, it will auto-range but I just don't have the experience to trust what I am reading. I need to practice measuring AC/DC, resistance, capacitance, continuity (I get this one, I have learned to purchase old appliances that still have continuity) etc.

There is a gent on youtube, Mr. Carlson's Lab, and he has design schematics you can purchase to build test devices that can check for leakage. I will be making a leakage checker for caps, he is a very informative teacher.

I am going to purchase a few replacement resistors and caps for the tv and learn to identify, charge, and test for various aspects using the DMM and perhaps practice with the RCA vtvm.

[JohnCT]

Originally Posted by BandDirector

I have a Klein DMM that is actually pretty decent. My issue is that I never seem to get the same readings unless I set it to capacitance, which I think I can trust.

You MUST have a meter you can trust or you will spin your wheels. I only use Flukes, but I've had even those go wonky after a decade of daily use.

Out of circuit, there should be zero differences between readings. If you're using clip leads, make sure *those* are in good shape and reading zero ohms, even when flexed.

In circuit, all bets are off without examining the schematic.

John

[Notimetolooz]

BandDirector,
I would not waste my time by building a cap leakage tester.
Follow the words of the experienced people here. Don't bother testing the old electrolytic capacitors. As was said vintage (in my book older than 1980) electrolytics need replacing. All capacitors with paper internal construction should be replaced. Those types were used into the mid 1960's. Many of the available methods of measuring capacitance can be thrown off by leakage.
Capacitance measurement with the capacitor still connected to the circuit usually will not work.
Sometimes resistors can be tested while still connected, it depends on the circuit. When you measure low resistance a good electrical connection at the probes is very important.
You actually have some pretty good test equipment compared to other people just getting started working on electronics. A tube tester might be a good addition as well as another type of RF generator. You don't need it for you present projects but an isolation transformer could come in handy in the future. A variac would be useful for the transformer sort-out.
When a radio was suggested, I believe something with fewer tubes was what people had in mind, 5-6 tubes.
This website is a goldmine of information. Explore it, starting with the Beginner's section.
https://www.antiqueradio.org/welcome.htm

I have, today, received an unmolested chassis, tuner, and volume/power switch, and deflection yoke. This was a find via Radiola- the gent happened to have the same console, "Norman", KCS 116C. This chassis has a properly working transformer, so this will be a slow process of getting to know you, and getting to know how to carefully replace caps.

I have had a few successes with my Stromberg Carlson, and a friends Motorola; the latter after laying in new caps parallel to the old and replacing the vertical tubes produced an image that was remarkably watchable.

Now the fun part, replacing the electrolytic caps. My one question for wiring the filter caps- how do you tie the leads together to give you the 4 terminals (for Can 1), and 3 terminals (for Can 2)?

Electrolytic caps are polarized, right? So I need to tie in series or parallel? Do I ground using a negative from the highest capacitor? For example: can 1 will require 4 caps, 100 mfd, 40 mfd, 20 mfd and 20 mfd. Is the 100 mfd negative lead sharable as a common ground to the chassis? How do I tie these together to make 4 terminals for cirtcuits and ground?

Thanks all!

[old_tv_nut]

All of the new negative leads need to connect to the chassis electrically (assuming the old negative leads connected to the chassis), but it is OK to connect the negative lead of one capacitor to the chassis and then connect the remaining negative leads to the first negative lead. It doesn't matter which one you start with.

A positive lead must individually connect to the wires that went to the positive lead of the original capacitor, but must not connect to the original capacitor itself. You should end up with no wires connected to the old capacitor positive leads (or lugs). In other words, the old capacitor outer aluminum can or negative lead can remain connected, but its positive lead must be disconnected from the circuitry and not connect to anything.

This may require installing a terminal strip to provide isolated connection points for the new positive leads and the old associated wires.

If the old negative lead did not connect to the chassis, you need to provide an isolated terminal for the negative lead of the replacement as well as the positive lead.

Check my bungy-setup for my stack of electrolytic caps.

In the picture you can see a loop of plain 110v cord, joined around the chassis and locked with a bit of solder. The farthest right terminal is both grounded to the three Neg. (-) terminals on the caps, and grounded to the chassis via a piece of 110 cord. Is that acceptable for carrying that current if needed?

Two of the caps have only one line, feeding the HV circuitry, the third includes two resistors that I may just replace with newer Rs with longer *radials. (*is that the word for the leads coming off of caps and resistors?)

The Pos. (+) leads from the caps have heat shrink protecting them, and are joined to the terminal block with a bit of solder. I'll need to check to see if there is clearance when the chassis is put into the console.

So far I feel good by checking each cap on the schematic, then clipping the old, using the old leads to solder the replacement cap, and clip any remaining metal from the lead (*radial?).

Double check each cap value before replacing. Slow but steady work.

[Electronic M]

It's probably electrically sound. Most caps have low enough current that non-stranded phone wire is thick enough (but phone wire usually doesn't have enough insulation voltage rating to be ideal).

I would recommend drilling a hold in the chassis and screwing (or soldering if your iron is rated 60W or more) the terminal strip down to the chassis rather than leaving the thing supported by just wires.

Caps smaller than your thumb usually can be safely supported by just their leads if connected to solidly mounted terminals. Caps bigger than that I often use cable ties (aka zip ties)...some hardware stores stock zip ties with a screw hole eye on the ratchet end...those you can snug down on a cap then screw the zip tie to the chassis.

There are other methods like restuffing the original lytics too.

What matters is that the right points are connected together and not shorted or prone to shorting and that it's all reasonably mechanically sound (not going to vibrate apart or break under likely conditions of storage and transport).

Leads are leads...caps with radial leads have the leads protruding from one side of the cap and on a round cap they are on different points on the radius this lead location style is called radial....Caps with axial leads have one lead coming from each end and those leads form an axis line (or you could say the cap looks like the axle on your truck if that floats yer boat) and that's why they are called axial lead caps.

I'll try to solder the block to the chassis, and I have some zipties floating around of different lengths/colors.

The big problem is lengthening resitor leads.

[Electronic M]

Originally Posted by BandDirector

I'll try to solder the block to the chassis, and I have some zipties floating around of different lengths/colors.

The big problem is lengthening resitor leads.

If you can mount the terminal strip at the bottom of the old can that should reduce or eliminate the need to lengthen leads.

BTW Mouser carries a variety of terminal strips that are exact matches to those used in most tube electronics they are a nice way of making a new terminal strip blend in with it's surroundings. I can post some links if you're interested.

I don't mind the little terminal blocks, they came in a big bag of 2-4 pin terminals plus a ground and mounting hole.

The issue is just where to fit the 100 mfd caps, they're about 1/3 the length of a roll of quarters, and weigh the full weight of the roll!

Overestimated the cap weight, anyway- nearly gained religion trying to get this arranged

[fixmeplease]

In post #67, the 2nd pic near the top where you replaced a bunch of caps. Between 5 new caps i think their is a bumblebee cap... possible its a resistor but I think its a cap. Your schematic will tell you which it is.

Originally Posted by fixmeplease

In post #67, the 2nd pic near the top where you replaced a bunch of caps. Between 5 new caps i think their is a bumblebee cap... possible its a resistor but I think its a cap. Your schematic will tell you which it is.

The pic was taken before I caught that, went back and replaced it and uploaded the old pic. I'm about to finish installing the second set of lytics, then going to see what happens!

I lack about 15 caps overall to finish the recap, but the original owner of this chassis said the low volt rect had a hard glow, so I want to check to see if new filter caps eases the pull on that plate.

No life in the crt, all tubes lighting up, power on/off worked. Need to attach speaker cables tomorrow and listen for noise.

Heater in crt did glow, no images/snow on screen.

Only left it on for 5 ish minutes. So it may need to be on longer, will try more tomorrow.