Shango, having spent almost 40 yrs in the TV and appliance service business, I've come to respect your troubleshooting skills immensely. Well done sir..
"The headphone jack has been bypassed. You can no longer use your 300$ Beats premium headphones with this radio." Thanks for the great commentary, Shango!!
I have a box of those bar antennas, from Olson electronics, early 70s and its followed me since childhood where my electronic interest began with radio.
Maybe some kid that was interested in electronics opened this radio up a bunch of times. That kid could be a electronics engineer now because of this radio.
That sounds exactly me when I was 8 or 9. Had a cheap Realistic radio that an uncle gave me, I must have take it apart and fiddled with it dozens of times. I did become a telephone engineer in the end. And I've assembled a couple of those Chinese radio kits that Shango had, so my interest is definitely still there.
The noise could be a phasing issue with the primary and secondary coils in the loop antenna. I’d try switching one or the other and see if there’s a difference.
Hello Shango066, I guess it still has an issue in the HF amplifier section. That's being controlled by the AVC, preventing the AM demodulator from being oversaturated with signal. When the HF amplifier is very weak, it will cut off without signal coming in. So it will be quiet between the stations. When there is some signal, the HF amplifier comes to life and the AVC is going at maximum to provide enough signal to the AM demodulator. But it's still weak and very noisy. It will may not cut off the transistor in the HF amplifier section, but it can cause a lack of signal somewhere else in the circuit. Just a guess. Nice video!
Pull turns off the antenna till it sounds right i use a hair dryer to melt the wax and unravel one turn at a time but man nice job you got it alive agian and functional agian .
That AM bar antenna was originally designed to feed an IC (wich usually have higher input impedances), it should have a lower turns tap for the converter transistor to be better impedance matched to its base. Squealing and higher noise can occur, supposing the transistor is good.
I'm guessing that the antenna is going to couple to the band-pass filter thru something like a 10pF cap. U could try a different value for that cap, as it would be a series-resonant circuit, and the "new antenna" would have a different inductance value than the original design. Also, that thing might have an RF amp as well, and I'd make sure that transistor was still biased correctly. Since it's probably PNP, it might also be the cause of the noise, developing whiskers and such. It's hard enough for us to diagnose this without a schematic, of course. :D
Shango, just do this. Measure the resistance of the the two coils. The bigger resistance should be the actual antenna, and the smaller resistance (secondary) will be lower to match the input to the front-end better, however they have that setup.
Hey fellas. Any ideas as to how one could test this? Grid dip meter? Maybe sweep generator at RF frequency and measure....? Measure IF or audio output with modulated RF? I'm just thinking about the analytical objective/instrument side of the conversation. Thanks and God Bless!
Those screws in the beginning aren't worn, its just a new type of screw design by Apple so that no one can open up unless you buy their 15,000 dollar screw driver set sold only to certified Apple technicians which you will have to pay an additional 100,000 dollars to become one. 😉 BUT WAIT ! They will give to you a second screwdriver set for FREE ! (just pay a separate shipping and processing fee)
Wouldn't help you anyway. All of the chips are married to each other. I like apple computers and swear by them but in reality they are $3k disposable items.
ГТ309Д is rated for up to 40 MHz. А and Б versions are for up to 120 MHz. It is too weak for FM. I recommend to use any of ГТ313. Any of them are for 300 MHz at least and their military grade versions (1Т313) are for up to 1 GHz.
Glad to hear they still transmit The Family Bible Reading Fellowship. I used to listen to Family Radio on the short wave band in Mexico, my begginins as a Christian and a deep liking for old radios.
That is (was) a really nice radio, Mr Shango. Your frustration is justifried only in the sense that this particular example was beat to s**t. Nice job.
A very enjoyable and interesting video. I watched it a few times to get a better understanding especially on the fault finding side But Being a dyed in the wool Tube guy I thought I come and have a look at the dark side (Transistors Devil's work ) lol I got to confess being so small would be to frustrating and fiddly for me to work on so hats off to you guys . give me a 12AX7 and an I F Can you can rest your coffee cup on any day. Regards from a new subscriber from over the pond
A few beers, pizza, and ask him which are his favorite items in his collection and why? And what are his education, vocation, and previous jobs and work experience. That would be fun. God Bless
Have you tried replacing the AM diode and any capacitors after it. There is usually one to take any IF or RF to deck and pass the audio through. I had a Russian Set with a similar problem. Changed them both!
The noise in the AM could be because the inductance of the ferrite bar antenna is not matched with the tuning capacitor. Even though you matched the top of the band with the small trim caps, and the sensitivity and selectivity are there (both are provided by the IF amplifier) the bottom of the band is still not matched and hence the bar antenna doesn't resonate there with the fully meshed tuning capacitor. The hint is that you had to add extra capacitance to get the top of the band into tune. The tuned LC tank at the frontend (bar antenna inductance + tuning cap) keeps a lot of noise away from the converter, besides suppressing the image frequency. Without the LC tank being in tune, everything gets into the converter stage, including all the noise.
AM mattered a lot. Now the only effort put into audio products is to have bluetooth and USB. AM (and FM) performance are far, far down the list of priorities on the vast majority of modern audio products.
@@LakeNipissing There are actually people who refurbish vintage radios and then install Bluetooth modules into them. Like a vintage radio really needs Bluetooth functionality.
5:48: Then there's me, who uses the ⅛" Headphone Jack on my T/O 7000 for private listening (w/In-Ear's that came with my Galaxy S9), as well as on other vintage electronics. So if I acquire one of these Royal 51's, chances are I'm gonna use that headphone jack from time to time.
Great fix! But a coupleof q's: (1.) If there were an inherent gain to that tube stick ...could it be a bit off (high) for this set and causing this issue or would that even be possible? (2.) Also, you mentioned there was a capacitor wire on that stick....would a cap there have any affect in cleaning it up?
The reason you got the same station at the top and bottom of the dial was due to image frequency response. In a single conversion radio you will get a "ghost" at double the IF frequency lower than the real frequency.
I had range anxiety until I traded my Tesla for a 1995 Toyota Celica. ICE cars eliminate that problem. The selectivity of the radio is great, but I can't listen to noise behind a signal, the snow, waterfall etc. I have no useful advice to offer, but I personally would not consider the radio to be usable as it is..
The bar antenna is the problem with the noise. IDK what your patience level is but you could get the spec of the original and wind out your own and put in there.
@@williamstevens7090 That's good to know. When I searched on eBay, I couldn't find a seller for this in North America. The LW/MW/SW tuning capacitor seized on my Nordmende Globetrotter 808, the dial cord snapped, and that's when I was on the hunt for it.
Shango were did you find the exlite green flathead screw driver I had one let some one borrow it never saw it again. I only have the pocket green ones .
Hi Shango, I have an SX-727 that has a noisy AM Band where no matter what station you tune in it makes that waterfall noise you're talking about that this Zenith is doing, and as far as I know it has it's original AM Loopstick Antenna. Could it possibly be the same issue as your Zenith is having, a mismatched AM Loopstick?
The solder blobulator on the IF can is way too big; that size is only appropriate for sets with dead spiders in them. Adding some rat nest material will twinklefobulate the AFC and bring the set to life. This is only a test. We now return you to your normally scheduled program. 🤓
I think the excess noise is from a leaky transistor. At 41:02 "How many kilograms of hydrogen are at each station" Did you pick up a Canadian station on E-Skip?
No, definitely not, it was daytime... the signals can't bounce off the ionosphere with the sun up. (Can't tell you why, it's just a fact.) DXing works best around 10:30pm-2 am from my experience...
@@joeblow8593 Ah ok, thank you, Joe. I mostly play with AM. But with my little experience in fm I’ve never witnessed E-skip though. My friend actually just mentioned hearing a distant station o fm while I was over at their house with one of my am sets. Maybe I’ll start doing some more fm stuff too! I also should of payed attention to what band he was on before I made my comment... Thanks, Have a great night! -Nick
what's the song at 26:03 sorry but I've heard the song before but i can't remember what the name of it is. By the way Shango you do great repairs and have great videos keep up the great work
I doubt it's a transistor if the noise only occurs when on a station, I would think you would hear it all the time. It's likely that the antenna just isn't a good match, as evidenced by the fact that you had to pad the tuning condenser to make it work
42:48 Who is that? I'll have to go look at it. Local AM played song from slightly obscure artist. Female vocalist singing something about a black dress. I liked it and thought similar thing. Throwback to 1970's pop that you could just groove to rest, work, or grab your bass and plug in quick and see if you can get the rhythm and hit the changes. Yeah, baby!
That was easy. Post Malone - "Circles" I could gave asked my niece! And tease her by saying, "Malone-ay!" With my thumb and pointer finger tips touching and shaking my hand at the wrist. She'll say, "That's not how you say his name!" RU-vid couldn't help meet figure out the other one. I'll get back to you here if I figure it out.
