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 Post subject: Re: Newbie - What equipment do I need to restore a radio
PostPosted: Dec Thu 31, 2020 6:28 pm 
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tgr131 wrote:
I have gathered I need a multimeter, an oscilloscope, a signal generator, and isolation transformer, and a variac(sp?) limiter.
David
You do not need the oscilloscope and variac. It is a simple radio.


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 Post subject: Re: Newbie - What equipment do I need to restore a radio
PostPosted: Dec Thu 31, 2020 6:50 pm 
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Yes you need incandescent. That has the voltage to current vs time characteristic you need for gentle powering of the unit.


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 Post subject: Re: Newbie - What equipment do I need to restore a radio
PostPosted: Dec Thu 31, 2020 8:28 pm 
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tgr131 wrote:
I don't know yet if this will be a single project, or if the bug will bite and this will become a hobby.

I have gathered I need a multimeter, an oscilloscope, a signal generator, and isolation transformer, and a variac(sp?) limiter.

Can any of you recommend a budget friendly way to get started?

The Zenith J733 is a relatively simple transformerless (aka AC/DC) AM/FM radio. The odds are good that if you are careful, it will work after replacing the electrolytic and paper capacitors, any resistors that have drifted enough to warrant replacement, and maybe the selenium rectifier. The odds are also pretty good that it will work acceptably without having to realign the tuned circuits. So you probably won't need a signal generator to troubleshoot or align the radio.

Since you don't need a signal generator, you can dispense with the isolation transformer, provided that your multimeter is battery-powered (no line cord). And since you won't be doing an alignment, a digital multimeter is perfectly fine. Finally, you didn't need the variac or oscilloscope anyway.

I suggest you buy a digital multi-meter that is a cut above the Harbor Freight cheapies. The cheap DMMs often won't read resistances above 1 megohm and usually have a relatively-low input impedance of 1 megohm. You will want a DMM that can read resistances up to 20 megohms, and that has a 10 megohm input impedance.

You will need a small (40 watt or so) soldering iron, rosin-core solder, solder-sucker and/or solder-wick (for removing the old solder from wiring terminals), small diagonal wire cutters (5 1/2" or less in size), a small pair of needle-nose pliers (again 5 1/2" or less in size), and screwdrivers to fit the screws on your radio.

If you already have a larger pair of wire cutters or needle-nose pliers, go ahead and try using them. The chassis on the J733 is pretty crammed, though, so the smaller tools will be easier to use.

If the radio ends up not working, and we can't get it fixed using just your multimeter, then it would be best to look for a local antique radio club or another antique radio hobbyist who has a signal generator and can help you find the problem, or align the radio if that turns out to be necessary.

Where are you located?

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 Post subject: Re: Newbie - What equipment do I need to restore a radio
PostPosted: Dec Thu 31, 2020 9:26 pm 
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Yes - you need incandescent and one that matches the power draw of the radio.
There are plenty of simple plans on You Tube


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 Post subject: Re: Newbie - What equipment do I need to restore a radio
PostPosted: Dec Thu 31, 2020 9:40 pm 
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search this forum, there many threads on this. Also, there are many bloggers out there that have helpful startup info.

this guy - past teacher does a nice job of showing you how to do thing w/o much equipment. scroll through his post, you find voltmeter technique servicing old radios like others stated.

https://www.youtube.com/channel/UCUEo3L ... GJQoE0i1Gg

I am new to this hobby too, I have heard tube FM radios are not easy to align and very finicky. start simple.

When I started getting back into this hobby, (before cov19) I was ordering all kind of chinese components. They are not that useful, prob only use in breadboard experiments. if you trust them.

safety most important, search this forum for isolation transformers, etc.

have fun, feel your way into the hobby to make better $ choices

edit- if you can find a mentor close by you, ++++ (cov kind of squished that)

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 Post subject: Re: Newbie - What equipment do I need to restore a radio
PostPosted: Jan Fri 01, 2021 12:03 am 
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bob91343 wrote:
Yes you need incandescent. That has the voltage to current vs time characteristic you need for gentle powering of the unit.
Why? I can't think of any purpose it would serve. I've never had one, and have redone many radios. Of course, those who try to reform old capacitors might want it, but that is as much a waste of time as trying to reform politicians.


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 Post subject: Re: Newbie - What equipment do I need to restore a radio
PostPosted: Jan Fri 01, 2021 12:10 am 
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Location: 13 Critchley Avenue, PO Box 36, Monteith Ont, P0K 1P0
There is equipment that you "need"
There is equipment that "makes life easier"
There is equipment that "you want", just because.
There is equipment that fits none of the above brackets but is cool and makes you feel good.

I suggest buying it all.

Ok, seriously, after almost 50 years of doing this foolishness, I would suggest a good new digital scope, a good new digital signal sweep generator, a good new DVM. In addition, a good used VTVM, a few used power supplies of various outputs, both AC and DC, and an audio load to replace speakers when doing alignments. A GOOD soldering iron and a GOOD soldering gun, a GOOD solder sucker will make your life much easier and slow down the speed at which you learn new profanity.

Also .... a WOOD workbench, a properly wired set of grounded outlets with GFCI, a big rubber mat to place your chair on and a piece of tight knap carpet to place your radios on when working on them.

That should get you started.


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 Post subject: Re: Newbie - What equipment do I need to restore a radio
PostPosted: Jan Fri 01, 2021 12:16 am 
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just trying to be easy on the ears.. you can get into this hobby w/o a lot of $

sure I like to have a complete bench. it would take me more time to figure out how to use the equipment than fix radios.. but it's all fun.....

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 Post subject: Re: Newbie - What equipment do I need to restore a radio
PostPosted: Jan Fri 01, 2021 12:21 am 
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I disagree - no soldering guns for me. As for dim bulb testers, some like them. I have never used one and prefer a hands on approach. My hand's on the variac knob.

Actually unless I have a reason not to, I often will just plug a unit in and see what explodes. If I am nervous about it, especially if I have just replaced major parts, I'll bring it up with the variac. I am also aware that some circuits don't function well with gradual increase of supply voltage.


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 Post subject: Re: Newbie - What equipment do I need to restore a radio
PostPosted: Jan Fri 01, 2021 12:25 am 
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bob91343 wrote:
I disagree - no soldering guns for me. As for dim bulb testers, some like them. I have never used one and prefer a hands on approach. My hand's on the variac knob.

Actually unless I have a reason not to, I often will just plug a unit in and see what explodes. If I am nervous about it, especially if I have just replaced major parts, I'll bring it up with the variac. I am also aware that some circuits don't function well with gradual increase of supply voltage.


https://www.youtube.com/watch?v=MyRXWBrXDQU

he has some videos with ac line into caps - is that u?

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 Post subject: Re: Newbie - What equipment do I need to restore a radio
PostPosted: Jan Fri 01, 2021 12:32 am 
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nope


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 Post subject: Re: Newbie - What equipment do I need to restore a radio
PostPosted: Jan Fri 01, 2021 12:48 am 
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Location: 13 Critchley Avenue, PO Box 36, Monteith Ont, P0K 1P0
bob91343 wrote:
I disagree - no soldering guns for me.



Soldering guns for chassis soldering, unless you have a BIG iron, but that's pretty much the same thing in a different package.


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 Post subject: Re: Newbie - What equipment do I need to restore a radio
PostPosted: Jan Fri 01, 2021 1:04 am 
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my weller 140w has 10 gage copper loop, my 260 has reg tip.. could not work on this old stuff w/o at least one. prob have thinking backwards 140/260 both do its job. one starts fire faster then other. not sure how you do heavy soldering w/o these or iron? maybe newer stuff can withstand the workout?

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 Post subject: Re: Newbie - What equipment do I need to restore a radio
PostPosted: Jan Fri 01, 2021 7:09 am 
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Quote:
The Zenith J733 is a relatively simple transformerless (aka AC/DC) AM/FM radio. The odds are good that if you are careful, it will work after replacing the electrolytic and paper capacitors, any resistors that have drifted enough to warrant replacement, and maybe the selenium rectifier. The odds are also pretty good that it will work acceptably without having to realign the tuned circuits.

Given this, all you really need are a soldering pencil type iron, solder, needle nose pliers, dykes , and a meter.

It was suggested in a previous post to get a better than Harbor Freight unit, but for just starting out with one radio, and not knowing if the bug will bite, that would be sufficient for a beginner.

In fact if you look at the ads on the right side of the page, Sal's Capacitor Corner has not only caps, but offers a multimeter for $2.75. You may however want a higher wattage than his $2.00 iron offers.

It would be good if you could learn how to trace a schematic diagram, as you could then most likely recap this simple circuit before breakfast.

Welcome aboard and good luck in the endeavor. Please continue this thread to keep us posted on your progress, or of course any questions.

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\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins/////////////////////////


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 Post subject: Re: Newbie - What equipment do I need to restore a radio
PostPosted: Jan Fri 01, 2021 5:06 pm 
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Here is an article on the construction and use of a dim-bulb tester.
https://www.antiqueradio.org/dimbulb.htm

Sal's even sells a assembled dim-bulb tester, although if you can't find the parts and build one yourself it is doubtful that you are going to be able to restore a radio.

A dim-bulb tester limits the current in the case there is a short in the power supply section of the radio. The bulb can be thought of as a self-healing fuse. Assuming you selected the correct bulb wattage, if the bulb lights brightly then there is a short. (For instance the power cord on this radio being installed wrong.)
It probably also serves as a learning tool for newbies. With a working tube radio you can tell by the bulb brightness how the current changes as the tubes warm up (it is higher at the very beginning).

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It's not the Destination, It's the Journey.


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 Post subject: Re: Newbie - What equipment do I need to restore a radio
PostPosted: Jan Fri 01, 2021 9:27 pm 
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If David tgr131 is still looking I would suggest he first look to see if there is a Antique Radio club in his area.

If so they would welcome him as a visitor when this Covid-19 is under control. If he elected to join the dues are typically $20-$30 annually and give access to members that know the theory and application of it to the old tube radios. By that I mean members that are capable of pointing him in the right direction. Enough theory to understand ohms law and the various components that make up a radio along with the ability to read a schematic that shows the interconnect of the components.

Rule out anyone that promotes replacing all the capacitors before even turning it on. For those that are really interested in repairing radios and electronics in general the fun is in troubleshooting right down to the defective part. Then depending on the age of the radio you may want to replace the electrolytic and tubular capacitors.

If a club is not nearby google for online help, but keep in mind its about taking one step at a time. Of course help is always available here, but it gets so disconnected a beginner will likely have difficulty and may become discouraged.

Just like building a home the foundation goes down first before its built on. Take your time and make the learning process fun.

Stay safe, Bill


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 Post subject: Re: Newbie - What equipment do I need to restore a radio
PostPosted: Jan Fri 01, 2021 11:25 pm 
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& some sort of solder sucker, hand pump ones work good.

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 Post subject: Re: Newbie - What equipment do I need to restore a radio
PostPosted: Jan Sat 02, 2021 7:47 am 
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tgr131 wrote:

Thanks for any advise as I consider setting out on this expedition.

David


Your expedition is one of an education. I think the best thing you can do to help yourself is buy a few books on the subject and read these first, before doing anything else or buying any test equipment, except perhaps a multimeter.

Ideally the the books would cover topics such as:

1) Basic electrical theory, Ohm's law and its relatives as presented on this thread.Voltage, resistance & current and power. A read up on electrical safety is also wise.
2) Principles of passive components, inductors, capacitors, transformers, power & RF types. Principles of power supplies.
3) The basic active components, tubes, transistors, Fets and their theory of operation.
4) If it is radios you are interested in mainly, there are many good books on tube radio receiver servicing.
5) Do some construction projects of a few simple circuits and hone up your soldering skills. AM radios/kits and small amplifiers, oscillators, start with low voltage designs, this will teach you to read and draw schematics.

(Others can make more suggestions for reading material. A very good electronics text is The Art of Electronics by Horowitz & Hill, but it is not geared to tube circuitry, put the principles of the passive components, semiconductors, IC's analog & digital circuitry are well covered & explained well)

After that you will be ready to decide for yourself what test equipment you should buy, especially "Why you would buy it and how you would use it" and to dive into vintage commercially made equipment with a good hope of repairing it.

The best piece of equipment in a laboratory is the thing between the ears, so if you have prepared that well with your study, you are >90% there and the rest will come with experience & time.


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 Post subject: Re: Newbie - What equipment do I need to restore a radio
PostPosted: Jan Sat 02, 2021 2:45 pm 
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https://www.udemy.com/course/crash-cour ... cb-design/

Never hurts to have a teacher. I took the course and was extremely happy with it. Recommended it on another forum with many members signing up. Normally $100 on sale right now for $10. Starts off with just basics and graduates to digital and extremely complicated. At least for my 71 year old mind. For about the price of a McDonalds meal you will learn electronics from the ground up. At my age wading through a book is not my idea of fun. This course was fun and enjoyable to me being somewhat of a nerd. A 900 page book is included with the course. Best deal out there. Many electronic engineers take the course as a refresher course as well as newbies. I decided to take course as a refresher but learned much more than I thought I knew about each and every component. The info helps solving problems in electronic equipment.


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 Post subject: Re: Newbie - What equipment do I need to restore a radio
PostPosted: Jan Wed 06, 2021 12:25 am 
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tgr131 wrote:
Thank you for all the feedback, and you're not scaring me off -- just instilling a well founded respect for safety.

I've accepted that this is going to be a slow project for me, as I need to gain a variety of skills and understanding.

The radio's seller has already scared me enough, as she tried plugging the radio in, and said the cord sparked, so she "helpfully" replaced it, :shock: , and tried to replace a bulb that lights up the dial. Sounds like I've picked a complicated project to cut my teeth on, and she might have just complicated it more.

Thanks so much for all of the advice.

David


My 2 cents. One thing to consider is do you just want to get this one radio working and do it cheap or do you want to learn, have fun, maybe fix other radios or stuff, etc. I had never even seen a tube radio before but me and my dad took on a 1936 buick Am tube radio project. In the beginning, we decided, this will be to learn and for fun and might do more. So, got a scope, dmm, power supply and frequency generator. Was not even sure how or if we would need the scope or freq gen. Could have just got a DMM and replaced a bunch of caps and hoped for the best. But glad we got the extra stuff, it made it more enjoyable during the whole project. Used freq gen to generate AM modulated signal and was able to run it from antenna to speaker and play a selected tone. Thought we had good B voltage as far as DMM voltage goes but then looked at it on the scope and it was horribly noisy. Replaced filter caps and looked on the scope again and the visual difference was glaring. Could use scope to look at RF and AF waveforms and even ran an FFT to look at frequency components. Will see if we can run frequency sweeps to look at IF selectivity, and whatever else. So, guess it really depends on what you are trying to accomplish and what its worth to you to shell out some money for it.


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