[g8wayg8r]

I've stumbled into another big radio. I was talking with a friend at work that tinkers with all sorts of things like I do. We got on the topic of radios and he mentioned that he had an RCA 10K that was his ex-wifes grandmothers radio. It was taking up too much room and he already had a upright that belong to his family so he said it was mine if I would pick it up.

He mentioned that it and the tuning eye worked but I didn't feel compelled to plug it in until I had a chance to take a good look at electronics. The finish on the case needs to be stripped and the walnut veneer on the top replaced. There are few other places that could use a patch. I'm not sure how to proceed with the front panel since there are decals. My inclination is to keep it as original as possible unless I can find out how to avoid destroying the decals. The plastic dial cover riveted in the escushion has yellowed and is a bit dusty. All of the bakelite knobs are in excellent condition and the tuner turns smoothly. The cloth grill is a textured gold with a floral pattern and looks original. If not, a tasteful replacement was made. There are four bass ports inside the enclosed speaker cabinet. The speaker looks to be in great condition. The power cord is cracked and must be replaced before any power is applied.

All I managed to do today was to vacuum out the cabinet. I got a woodworking project that's taking up room on my work bench where I work on my radios. Hopefully that will be done within a week so I can get to recapping and rewiring before I start the power-up procedure. Thanks to Nostalgia Air I've got a schematic.

Did I mention that this radio is HEAVY. Lots of wood in the cabinet. I all became the proud owner of a Hickok 209A vacuum tube multimeter as well. Not sure when I work on that but I suspect I should give some consideration to recapping that as well. Nice big dial that's easy to read and see on a work bench.

More to follow as the story unfolds. Any that's had experience stripping off old finish without removing the decals I would love to hear about it.

[jayoungs]

Hey g8waygtr,

IF the front panel is not in bad enough shape to require stripping, but the rest of the cabinet is, I've handled this same dilemna on some other consoles by:

1) Masking off all but the front panel and then using Restor-A-Finish with a heavy textured rag. It will bring the finish back and will not harm the decals. I usually apply two rounds.

2) Then, mask off the front panel tightly with a sheet of aluminum foil with edges overlapped with double thickness of heavy painters tape. Refinish the rest of the cabinet. NOTE: R-A-F will not take lacquer over it, so hence the necessity to mask it off. I use foil to repel any stray stripper getting to the panel.

3) Assuming you're putting a rubbed lacquer finish. At the point of having rubbed it down well, I then un-mask the front panel and apply/buff a good paste wax on the entire cabinet and then a couple of heavy coats of beeswax polish -- letting the first coat sit for a good 30-45 min before wiping out.

Hope that helps,

Joe

[exray]

Radiodaze sells replacement decals for that model.

[Dave D]

g8wayg8r, Several years ago I restored a RCA 10K and everythging went well and I thought I was done. The radio was going to be a Christmas present for my daughter. Just before Christmas I was doing one last check and the audio just died. After being off for a while it worked fine , then died again. When continuity checks were done I found that a cable going from the chassis top to the bottom was the problem. The cable is wrapped and when I removed the wrapping I found that all of the wires had insulation that had rotted out and many chances for signal shorting were available. A complete cable rebuild took care of the problem and the radio is still alive and well in San Antonio. Hope you don't have the same problem.

Dave D

[g8wayg8r]

Thanks for all of the great replies. It's nice to know the decals are available at Radio Daze. I've purchased odds and ends there so if I'm not happy with the Restore A Finish I'll look into it.

Lacquer. I haven't tested the current finish yet. The Philco 40-201 I worked on has shellac. Nice but tricky to use at first. Blushes easily. I've never rubbed lacquer so perhaps I'll give it a try. I will not use polyanything on it.

I need a full piece of walnut for the top. Easy to find. Stains. Hate them. would rather leave it natural but I suspect I'll have to do some color and shade matching. Not looking forward to that.

First impression of the chassis and the electronics. Lots of metal. All original parts except for the tubes. No metal tubes in the 30's right? The tuner assembly was a little tricky removing. Lots of links attached to the dial face but only the hub attached to the selector switch needed to be loosen to remove the "Magic Brain" - the tuner, coils, tube, etc for the RF, 1st Detector and Oscillator part of the circuit. The Brain is enclosed in a removable box that occupies the center of the chassis. Very clean inside. The electrical connection from the Brain to the chassis is made through cord attached to a multi-prong plug. I'll be sure to check the wire condition. Good news is there are only three paper caps that need replacing in the Brain. As with all 18 paper caps, the lugs aren't all that easy to get to so I may end up desoldering a few wires and resistors that I would rather leave alone. I'll do this one lug at a time. I have noticed that some of the wire insulation is beginning to crack but on the whole, the physical condition appears pretty good for something that old.

My next step is recapping. The original electrolytic cans are in place. One has a very corroded terminal. Never seen the inside of one. Guess there's a first time for everything.

[g8wayg8r]

I've been delayed making a hood over my 75-gallon aquarium. I've got two panels an artist will fill in some artwork. There's black spray painted cardboard in place now and it actually doesn't look all that bad.

After serious consideration I decided to repair the top of the radio rather than pulling off all of the veneer. As it turns out most of the problems were near the edge so the fix wasn't difficult. I patched two spots with some old walnut veneer scraps and injected glue into all of the bubbled up spots and loose edges. I'll do what I can to get the color right but it may be that old shellac in the pores of the old veneer that wasn't removed when I stripped to top with ethanol has darkened the walnut. I may put some on scraps of the patch and see if that will help.

Got all of my caps today and plenty of wire to replace the old, cracked plastic wire in the set. I also got decals from Radio Daze so I don't have to worry so much about losing the originals.

Not sure where to start. Anyone have a favorite place in the circuit?

[g8wayg8r]

A few odd looking capacitors. The set has you standard axial paper capacitor and the square to rectangular mica capacitors with the expected dot. The radio also has some rectangular black plastic capacitors that have round tapered ends - sort of football shaped. The capacitance is low, 5 to 500 pF typically and I'm not aware that any paper capacitors had such low capacitance. I have cut any off yet and I'm wondering if they stable like the mica capacitor or prone to change like the paper capacitors.

Anyone ever deal with these?

[exray]

Those lozenge shaped mica caps are not all that good 70 years later. If you roll one over looking for a value on the other side consider it toast!

On a set of that calibre I personally would replace them. I've found enough bad ones to not trust them categorically.

[g8wayg8r]

The Magic Brain
All of the plastic wires had hardened and cracked over the years. I replaced all of them and the bundled interconnect to the chassis. The split spring connectors must have been really nice at first. Most were not usable as designed but did provide an nice mounting point once the old solder was cleaned. I managed to break off two lugs and fortunately enough was left to connect and solder new wire. Rather than tugging at the wire when the solder melts its a much better idea to clip the wire first and remove the left over piece once the solder is cleaned away.

A few out of spec resistors were replaced but they were mostly good. All of the paper caps were replaced. I haven't paid much attention to the low capacitance mica caps since they read the same as the replacements. Both read high using the cheap multimeter I've got. I've notice that the the old paper caps almost always read higher than spec. Not sure why the new and old micas would do that unless it's a systematic fault with the meter.

More frustration
I'm moving on to the chassis and I'm out of 0.5 mf caps and I need to replace some out of spec resistors. Back to order more. Will it ever just slow down. I feel like the shipping and handling is going to eat me alive unless I can become proactive enough to know what I may need in the future.

Transformer wires
I'm not sure if I like what I see. All of the wiring is tucked away nicely and they lay on top of one another. The old fabric is looking old. How far can someone go into an old transformer and replace the wiring. 20- gauge OK?

Desoldering
Lots of ways to do it. I've been brushing it away. Vacuum would be nice but I'm afraid any of the fancier guns or stations would be choked by the massive blobs on most of the terminals.

Fuses
There are none. I'm guessing 1 amp is good enough. Not sure if it should be before or after the transformer.

[codefox1]

Well, a couple of hints:

Transformer: you can always unsolder all the leads, take the bells off, and take a good look. You could always slip some heat shring tubing (use the same color or you't go nuts later.) over the wire, but if it's really bad, you can usually strip back a couple of layers of wax paper and replace the wires where they are soldered to the windings themselves. The utmost caution, lest you break a fine secondary and don't have enough left to solder to. But mostly the transformer wires are pretty good, and if you get the heat shrink up into the bells, you don't have to disturb the transformer any more. If there are issues with a possible open winding, or overheating, of course this is another matter. Proceed with caution. You can also paint the bells while they are off, if you want to. Tape over all your new connections with several layers of electrical tape before re-assembly, Beware of any sharp points that may stick through and arc to the bells. Remember to put the cardboard shims back in, if there were any. Besides electrical insulation, they help to minimize buzzing. Measure everything before and after connecting the primary connected to the line (preferably through a variac, and go slowly and carefully) before putting the transformer back in the set. That way, you, and the transformer, and the radio have a good chance of a long and happy life.

Desoldering - You can buy some desoldering wick, which is a roll of braided copper which will absorb excess solder. You have to tin the end a little bit first, then heat it and apply to the joint where the glob is. Once the glob is gone, you will be able to see how the remaining connections are wound, and pick them out.

I often wonder if the production workers of yesteryear were paid by the pound of solder they used. I can remember saving solder scraps when I was a kid, which were melted along with the .22 bullets from target practice by my Dad, and poured into little ingots that were used as sinkers when we went fishing. Now, that was a real long time ago. Funny how you remember those things. Well, we didn't have a lot, and nothing went to waste.

I also use just a small screwdriver to whack off melted globs of molten solder, or again, a dull old dental exlporer which you can get from your dentist or hygeniest for the asking. Sometimes I wiggle the end of the part I am to replace while the solder solidifies, and then I can see how it is wrapped, and many times unwind it neatly with diagonal cutters, nippers, or dikes, whatever you call them. Anyway keep track of where the pellets land, and get rid of them immediately, lest they make new unwanted circuits for you.

Fuse - you can always add a fuse, and it's a great idea. 1 amp for the little 5 tube sets, 2 amps for the larger ones. You can use an in-line type on the line cord if you don't want to otherwise disturb the originality of the set. That way it's 100% reversable.

Ordering capacitors: Take a look at the typical radio you like to work on, count out what the typical values are, multiply that by how many radios you think you will recap in a year, and you've got roughly your number. Add in what electrolytics and micas you think you may need, and you'll come up with an order of, let's say $60-$100. Then, fill in the middle values, ordering a few here and there to make sure you have a reasonable assortment, then do it. That way, the 6 or 7 bucks does not hurt as much.

Somebody please fill in, I'm out of time, the url for the very good source for caps in Canada, has excellent web site, good prices-------- Gotta go for now.

Good luck



I learn something every day from this forum, so I like to contribute as well.

Well, thats my 2 cents worth for today.

[exray]

I haven't paid much attention to the low capacitance mica caps since they read the same as the replacements. Both read high using the cheap multimeter I've got. I've notice that the the old paper caps almost always read higher than spec. Not sure why the new and old micas would do that unless it's a systematic fault with the meter.

Coupla different things here.

On small value caps the leads from your tester can account for at least several pf of difference. Thats substantial when you get down to values like 25pf. Keep that in mind and go accordingly. Mica caps don't typically change in value unless they go way out of whack.

On the inexpensive meters you'll always get a high reading with leaky caps. Thats because they measure using the "time-constant" of the cap under test. T(time) = C(capacitance) times R(resistance). Once you add R into the equation (good caps don't have R) it bolloxes the readings. You can proof this on your meter by measuring a fresh yellow cap and then adding 470k or 1M of resistance across the capacitor under test. Thats a typical amount of leakage (DC resistance) found in old paper caps.

Not all meters behave this way. Just by accident I bought a new no-name Chinese do-it-all meter and it seems rather impervious to leakage. I don't know why? It doesn't have a brand name so I can't hardly go look up the specs My old meter did as you describe and I developed the mindset that if the cap doesn't read correctly then its bad for whatever reason.

The place in Canada for caps is http://www.justradios.com

Pay the extra buck or two for Expedited Shipping.

>>>quote: I also use just a small screwdriver to whack off melted globs of molten solder,
I always keep several x-acto knives around the bench. Whichever is in the worst condition at the time gets used for desoldering. Don't let the blade heat up. Makes a fine pick and is good for drawing off those solder globs.

-Bill

[g8wayg8r]

Thanks for all of the valuable input.

I think I'll be staring at the transformer for a while until I get the nerve to make a decision. I've used shrink wrap in the past of the exposed wires with brittle, fractured insulation and it's worked well. But, its the things I can't see that have got me bothered. You know it's got to be a hostile environment inside the case of the transformer than outside in the chassis. I must give this careful consideration. I could make matters worse than the need be.

I bought one of those do it all no name meters because it autoscales and for about 15 bucks it's a deal for doing quick checks. The capacitance does float around quite a bit sometimes.

I thinks I'll get some resistors and a .010 mf cap and play a bit tomorrow.

I've also got an older Fluke that I trust when I believe I have to make an accurate measurement but it doesn't give a read out on capacitance. When I need to make a measurement and consider it as the standard, that's the meter I use. The old Hickock meter has been turned on yet. Might be interesting to get distracted looking at it's innards until my radio parts arrive. It has a capacitance setting as well but I don't want to start out by plugging it in as seeing what happens next.

[exray]

I'm going to take a licking for saying so...

I don't know what Fluke has to offer these days, and they are probably made in China regardless, but I blame them for the bad rap that DMMs take. Guys complain about waiting for the digital display to settle down and whatnot.

I've only experienced such oddities when using a Fluke. I think they are about 20 years behind in technology. Ok, granted, they were good meters in their day as was the Simpson 260. Maybe still catering to an older customer. I'm sure they have 2009-era devices but I don't think I could afford them.

I searched my cheapo $29 meter and find its made by " Zhangzhou Weihua Electronic Co., Ltd. " Haha. Zhangu-what@!!

Not dissing your choice of meter, mind you, but I gather that you see as I do that you have to learn the oddities of any type of meter. I'll take my Zhangu-what over anything from Fluke that I can afford.

Sorry for stepping on any toes.

-Bill

[g8wayg8r]

On to the Chassis:
Very crowded. Lots of nodes with three or more connections. Many hard to reach parts. Lots of plastic coated wires to replace.

One very nice thing about this radio is the wiring diagram that's included with the schematic. I decided to start on the audio output since it was the most clustered. Spent a few hours going over all of the nodes so I could select a sequence to minimize the number of parts that were desoldered at any one time. For me I found it best to replace all of the capacitors, resistor and wires at a node without removing the old parts from the other end so there was less chance of connecting the new part to the wrong node. I also spent some time looking at the wiring diagram to find the location on the schematic to help verify that I'm using the correct replacement part.

All of the capacitors and any of the resistors off spec more than 10% were replaced. I'm not sure if that was necessary or not.

I left the three electrolytic cans on the chassis so I could use them to support the chassis while I was working underneath.

One thing I didn't care for with the design is chassis ground. Rather than attaching a terminal strip a tab was punched out to make the connection. Lots of heat and flux needed. That may not have bee a problem for the people making the radio but it is for me. I like my new parts untoasted. To get around that problem most of my ground connections were made to a quarter inch of the old capacitor or resistor lead that I would leave attached.

Heat shrink was pushed over the transformer wires. I'm ready to connect a new power cord soon but there's the cap pack with three capacitors and three resistors that are embedded in back plastic, which is housed in a metal box on top of the chassis. It will be a huge mess to melt and recover the box. For me, I'd rather just connect the components in a tight bunch and run the four wires as necessary to the pots. I'm not sure why the six parts were bundled in such a well build metal box. Is it shielding? If not I'd prefer to leave it hanging inside the chassis near the on-off switch.

Interesting comments about the Fluke meter. Mine is a hand-me-down that's probably 20 years old but the thing still works. Never had any problems other than to annoyance of selecting a new range all of the time.

[g8wayg8r]

I must admit I'm a bit lost reading the schematic around the cap pac that ties in with the volume control. The schematic and wiring diagram - even after printing on 11 x 17 paper - are difficult to read and I'm unsure about the voltage at the volume control. The cap pack looks like a tone control to me and I'm not sure how to size the resistors. [I think this is wrong. I've gone over other schematics and checked a reference book. Tone controls are frequently off the audio tubes. So, this is most likely part of the volume control that also filters 9/14/09] 166 volts and 3 milliamps makes 1/2 watt. I guessing that 1 watt resistors would be in order. I can't see how that part of the circuit could draw that much power but I'm a little short of confidence. With 2.5 M total and 970k max where the circuit taps in I'm looking at 65V and 1/4 watt resistors.

Back to the radio servicing book. I haven't had enough experience with the various parts of the circuit to know what to expect for typical voltage and current at the volume control and I'm starting to question what I'm calculating. It's getting late.