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Post by husker on Jul 14, 2008 22:35:30 GMT -5
Ok, guys I need some help with what looks like a huge receive issues with both my D201A's. Please keep in mind I am a beginner when it comes to working on radios. I have replaced v400 and v401, but the receive section is still very weak. I was reading about a specific resister that also needs to be replaced. If one of you incredabily smart guys tell me which one and what to use( where to find the actual new part) I will try to fix the issue myself. Ireaaly want to learn to work on these old radios and I will do the best I can if someone is willing to help me.
Thanks folks!!
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Sandbagger
Administrator/The Boss 
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Post by Sandbagger on Jul 15, 2008 6:18:35 GMT -5
Ok, guys I need some help with what looks like a huge receive issues with both my D201A's. Please keep in mind I am a beginner when it comes to working on radios. I have replaced v400 and v401, but the receive section is still very weak. I was reading about a specific resister that also needs to be replaced. If one of you incredibly smart guys tell me which one and what to use( where to find the actual new part) I will try to fix the issue myself. Ireaaly want to learn to work on these old radios and I will do the best I can if someone is willing to help me. Thanks folks!! Well, there is no "one" notoriously bad resistor that goes bad. The root problem is that the D201's used a very high (410V) B+ voltage in their power supply. While this is great for power output and the audio output, most of the lower level receiver and transmitter circuits operate at much lower voltage levels. But rather than have multiple power supplies, Tram chose to just use a multitude of 2 watt resistors to drop those high voltages down to the proper level for the respective circuits. Dropping that much voltage required that each resistor sink enough current that they all pretty much operate hot. In the short term, this makes for a radio that can substitute as a space heater in the winter time. In the long term, if the radio has a lot of hours on it, chances are that there are several 2 watt resistors which have changed value to some degree. I've seen grid bias resistors open, B+ resistors raise in value, and all sorts of chaos and mayhem in the well used Trams. I guess where I'm going with this is to say that a full restoration of a D201, not only requires that all electrolytic caps be changed out, but be prepared to change or at least check all the power resistors as well. The good news here is that a simple ohm meter can check these resistors and it shouldn't take all that much time to go through them all. Some may have to be lifted from the circuit to read properly. When replacing those resistors, it's a good idea to go to a higher wattage rated resistor, which will better hold up to the current demands of those circuits. |
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Post by husker on Jul 15, 2008 8:13:32 GMT -5
It would be a nice to have item if someone would actually create a "tune up" kit so to speak for these old radios. Many not a kit, but a kit per type of radio. Many of you folks know so much about these old radios that you could just about do this type of thing in your sleep.  I only wish I could get all your knowledge and bottle it !! |
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Sandbagger
Administrator/The Boss
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Post by Sandbagger on Jul 15, 2008 8:53:19 GMT -5
It would be a nice to have item if someone would actually create a "tune up" kit so to speak for these old radios. Many not a kit, but a kit per type of radio. Many of you folks know so much about these old radios that you could just about do this type of thing in your sleep. I only wish I could get all your knowledge and bottle it !! Well, it certainly would be helpful to produce a "100,000 mile tuneup" kit for these old radios. The problem is a practical one. Someone with a LOT of time, and not a lot of financial need would have to put it together. There is not a lot of demand, so there would not be a ton of profit potential, so the project would have to be a labor of love, and not one borne of a business need. Speaking for myself, time is not a commodity that I have an abundance of. That's why we have this forum. At least there is an archive of posts loaded with informative information on all these old radios. While certainly not a step-by-step kit, it's the next best thing. And to be brutally honest here, I'm not sure I would want to make an easy step-by-step "makeover" kit for tube radios. There are potentially lethal voltages present inside, and it's not the place for a novice to poke around without some experience and respect for volts and amps. |
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Post by husker on Jul 15, 2008 9:25:45 GMT -5
I agree 100% That's why I am asking so many questions..I am extremely concerned ( scared ) to start poking around inside. I want in the worse way to restore these wonderful radios, but I just don't have the knowledge ( or the time either). I guess I am looking for a quick fix when there is not a realistic one. I just wish I had the experience many of you folks have, heck I would love even 20% of your brains! I continue to print out posts for reference!!!! thanks to all of you! Bob |
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Sandbagger
Administrator/The Boss
Posts: 6,247
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Post by Sandbagger on Jul 15, 2008 10:17:56 GMT -5
I agree 100% That's why I am asking so many questions..I am extremely concerned ( scared ) to start poking around inside. I want in the worse way to restore these wonderful radios, but I just don't have the knowledge ( or the time either). I guess I am looking for a quick fix when there is not a realistic one. I just wish I had the experience many of you folks have, heck I would love even 20% of your brains! I continue to print out posts for reference!!!! thanks to all of you! Bob I know, I'm happy to help in any way I can, and this forum has several people who have several years of radio repair and experimentation behind them. So you're in good hands. |
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Post by mark4 on Jul 16, 2008 16:05:50 GMT -5
So glad you mentioned the lethal voltage potential in this radio. You start poking around in that radio and you will get nailed! Best thing is find a experienced tech-maybe he can give you some training. And you can find out if it's something you want to pursue. Some people learn the hard way. If you get a taste of 410VDC  you won't soon forget it or worse. |
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Post by husker on Jul 16, 2008 20:46:32 GMT -5
Mark4, that is one thing I will set your mind at ease with. Even when it comes to home repair, power is something I have ALOT of respect for. When I was 8 or so I tried to plug a train set billboard( 12vdc) into a wall socket. After I finally could stand up I noticed I was across the room! Not ever again! even though that was 38 yrs ago I still remember it like yesterday. I have a very healthy respect for anything related to AC or even DC. |
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Post by mark4 on Jul 16, 2008 22:21:00 GMT -5
That's good to hear.
Just never know who your giving advise to.
It scares me that someone may think it's safe to work on a radio and has no idea what they are touching.
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Post by Tombstone (R.I.P.) on Jul 17, 2008 8:57:01 GMT -5
Great advise about the voltages. A while back a guy brought me a Galaxy Saturn that he tried to work on the power supply with the radio still plugged in! Didn't do the radio or him any good but at least he's still breathing.
Tombstone
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Post by 2600 on Jul 23, 2008 1:31:38 GMT -5
A "tuneup kit" sounds like a good idea.
But that's all it is, an idea.
Wouldn't be worth much without a 'step-by-step' web page showing what part goes where in a logical order.
Just leads me to wonder how many of them you'd have to sell to pay back the cost of composing an accurate installation guide? Plus the up-front cost of a pile of parts, as well.
If it's under 20, that might be interesting.
But if I gotta sell 100 of them to break even, that isn't.
Food for thought.
The "shotgun" approach I favor is best for a radio that will be returned to regular service, with the idea it shouldn't break any sooner than necessary.
The "quick fix" is usually requested for a radio that's about to be sold. Make it work convincingly enough that someone will buy it. Never mind about next month, or next year. Just keep it cheap.
It's all about the result you want. Quick fix usually means quick fail, as well.
Trouble is, it takes a slightly different skill set to zero in on JUST one or two of the 18 resistors on the 'scorched earth" list.
Get the schematic from CB Tricks and start checking plate voltages on V300, 301 and 302.
Plate AND screen voltages BOTH on V400 and 401.
If both AM and SSB are dead on receive, the trouble may be in the 'shared' part of the receiver, V300 and V301.
OR, it may mean that you have dead stuff in BOTH the AM-only and SSB-only sections. Kinda depends on the mileage. And there's no odometer to read it from.
73
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Post by captbarry on Jul 24, 2008 2:26:58 GMT -5
Being a long time Browning owner (since 1977) the only thing I have done inside my birds was add the cap to get the "ping" and maybe a tube or two. Anyone who has the slightest bit of electronic knowledge does undestand that lethal voltage lives inside the cases of the Browning, Tram, and many other tube radios and amps. These two radios (Browning & Tram) are so complex and different from anything else out there it takes nothing short of a good engineer to work on them. I have said it before and I will say it again. Despite the cost of shipping my radios the quality work and satisfaction I get using 'em is well worth it. We are lucky to have two of the four people who I consider to really know how to keep these radio's in top form here on this fourm. I have said many times (and my wife would love it) that I have spent my last dime keeping my Birds going but that ain't gonna happen! Darn shame that Nomad Radio only has the carry in business for repairs cause I can't walk that far. Just my two cents but I will leave these radios for the pro's. Husker, good luck and be carefull.
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Post by husker on Jul 24, 2008 13:28:25 GMT -5
Being a long time Browning owner (since 1977) the only thing I have done inside my birds was add the cap to get the "ping" and maybe a tube or two. Anyone who has the slightest bit of electronic knowledge does undestand that lethal voltage lives inside the cases of the Browning, Tram, and many other tube radios and amps. These two radios (Browning & Tram) are so complex and different from anything else out there it takes nothing short of a good engineer to work on them. I have said it before and I will say it again. Despite the cost of shipping my radios the quality work and satisfaction I get using 'em is well worth it. We are lucky to have two of the four people who I consider to really know how to keep these radio's in top form here on this fourm. I have said many times (and my wife would love it) that I have spent my last dime keeping my Birds going but that ain't gonna happen! Darn shame that Nomad Radio only has the carry in business for repairs cause I can't walk that far. Just my two cents but I will leave these radios for the pro's. Husker, good luck and be carefull. Thank you sir! I am always careful as I want to enjoy the radios not be hurt from them. I also will be sending the better of my Trams to Greg to have him go through them as finances allow. But the two that I have as "donors" are the ones I am working on the see if I can learn some from them. again thank you for the kind words. Bob |
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you won't soon forget it or worse. 
