Dynaco FM-5
- Thread starter Donstaff
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KentTeffeteller
Gimpus Stereophilus!
Hi,
Your Dynaco likely needs new electrolytic capacitors, replacement of weak tubes (as needed) and a RF/IF/Multiplex alignment to perform as it did when new. This service is needed every 20-25 years of use. Do you have the assembly manual? Do you have any electronics know how? If so, and you have proper information and tools, you may be able to perform this service.
Your Dynaco likely needs new electrolytic capacitors, replacement of weak tubes (as needed) and a RF/IF/Multiplex alignment to perform as it did when new. This service is needed every 20-25 years of use. Do you have the assembly manual? Do you have any electronics know how? If so, and you have proper information and tools, you may be able to perform this service.
dshoaf
That high voltage buzz
The kit assembly manual does have an alignment sequence, assuming of course, that the tuner is indeed working properly to begin with. I have one of these and I seem to recall that there's a 'linearization' step where you have to adjust both ends of the dial in recursive steps to get it set up correctly.
I can also confirm that there are some electrolytic caps that need to be replaced in the power supply and in the 2-stage line-level amp for better audio out of this tuner. When its done the thing is a nice little tuner and the extra set of inputs makes it a tuner/preamp of sorts with a volume control.
Cheers,
David
I can also confirm that there are some electrolytic caps that need to be replaced in the power supply and in the 2-stage line-level amp for better audio out of this tuner. When its done the thing is a nice little tuner and the extra set of inputs makes it a tuner/preamp of sorts with a volume control.
Cheers,
David
Donstaff
Active Member
Thanks all. I'll look into replacing the electrolytics. I've built an FM-5, although not this one. The last tube Dynaco tuner, the FM-3 had a nice allignment procedure that required no special tools. However, the FM-5 assembly manual instead, says "There are no provisions for home alignment and under no circumstances should any alignment be made witout the following service equipment: 1. Sound Technology 1000A FM alignment generator, or the equivalent... 2. Oscilloscope-HP 130C or equivalent... 3. AC voltmeter with RM scle. 4. DC voltmeter... 5. Intermodulation Analizer.
All I have is an oscilloscope, AC VTVM and a DC volt meter. Is there anything I can do with these and would I be better off not even replacing the electrolytic capacitors in lou of additional test/alignment equipment?
All I have is an oscilloscope, AC VTVM and a DC volt meter. Is there anything I can do with these and would I be better off not even replacing the electrolytic capacitors in lou of additional test/alignment equipment?
Brian
An Old Geezer
I've had a few FM-5s come my way over the years and I maybe a majority of 1 but, it makes a good doorstop but not much else. Almost any tuner section of almost any inexpensive receiver will beat it. The only one I should have kept was the one that has the Dolby module in it. Only unit from Dyna I've ever seen with the module. Not knowing the history it may have been a mule as it was factory assembles. I've only seen proofs of the Dolby module ads and pre-production brochures.
Brett a
~◦●○o0o○●◦~
I had the opposite experience. I gave away my Sony digital tuner after digging my FM-5 out of storage. No comparison in sound quality and ability to pull in a station (which is not easy where I live)
Donstaff
Active Member
I have another FM-5 with the dolby mod. I did the mod. with a [VSM Audio, P.O. Box 114 Maspeth, N.Y. 11378] kit. Worked great for years before finally dying. Still plan to dust it off an see if I can repair it.
Have to disagree on the door stop though. It's too light for a door stop and it has decent performance for an at-the-time under $200 kit.
Donstaff
Active Member
Can't find anything about "'linearization'" in my FM-5 assembly manual. Could you be thinking of the FM-3?
reggaenaut
Addicted Member
So far your majority is sustained.
dshoaf
That high voltage buzz
Could well be, Donstaff. I do know that the FM-5 had a front end module that was supposedly prealigned at the factory. Frankly, I wouldn't be worrying about alignnments until you're certain the operating voltages are in good shape and stable.
From the looks of it, however, it looks like a pretty stock-standard tuner module down to the local oscillator/mixer with an 10.7Mhz IF output. I don't have the schematic in front of me but it seems like it would be reasonably straightforward to determine what needs to be adjusted for calibrating the dial scale.
Its funny, a quick check of the FMTunerInfo.com site has no information on the FM-5 but I did find a de-engineered front end schematic here: http://home.insightbb.com/~dunn.greg/FM5/frontend.jpg
Here's the rest of the IF strip: http://home.insightbb.com/~dunn.greg/FM5/schem.jpg.
BTW, I've had some luck using one of those little FM signal transmitters that are sold for adapting the iPod for playing through a car's FM radio. They plug into the headphone outputs on the iPod. What I do is to plug that into the output of my computer's sound card. This way, I can set a transmitting frequency and then control the amount of FM modulation with the volume control and I can pan the audio between the 2 channels.
This isn't the same as being able to set the FM signal levels but I can do a lot of troubleshooting and seat-of-the-pants adjusting on old tuners where I've got no drawings. This is how I 'aligned' my FM5. About the only thing I couldn't do well with this method was set the signal strength meter.
One last thought....I purchased my FM5 for about $20 from an audio gear dealer who was certain it was a gone-er claiming that they took it in from the original owner who said it had never worked. Turns out that the unit was kit built and had poor soldering joints. Once those were redone and the old electrolytics replaced, the tuner became rock solid and sounds good. It will eventually be my preamp/tuner in the garage.
Hope that helps.
Cheers,
David
Brian
An Old Geezer
The Dolby unit I had was not a mod but had the Dyna Dolby module that was advertised but never seemed to make it into the market channels and it has been speculated it was not produced. I never saw another and all of the literature from Dyna on it was it was going to be available in the future so I suspect the unit may have been a pre-production mule and I got lucky but did not give it serious thought at the time. As for the sound quality, as I said before, I am a majority of one and am unamimous in that opinion.