New Member FM-3 problems

Thid seems like a great forum! I've been browsing it for several days and just registered today. I've been building kits, etc for over 50 years, but drifted away from tubes. Now that I am 75, I have seen the light and returned to tubes. Recently, I installed the Welborne mod to a Stereo 70, and it opened my ears to detail I had not heard on many of my CDs, LPs, Reel tapes, etc. I ordered the PAS 3 upgrade from Roy and am 75% done - waiting for some parts. To make the switch complete (I was already using Dynaco A-25s) I just received factory built FM-3. It sounds very good, but the reception is only fair. Yhe only station I frequent is a low power university classical music station. anyway, I checked all the tubes on my Hickok 600A and they are all good. Now for the real mystery - I did not disturbe the eye tube (EMM801 I think from memory), As soon as I turned the tuner on, the eye did not close (previously it closed all the way) and the R in stereo is not lit. Is this a coincidence, or what?
Second Queastion: can someone recommend a good (not too expensive) indoor Antenna?
I plan to upgrade with the FM-3 Zone PEC and power supply later. Yes, I do have a spare eye tube, but am hesitant to use it until I finish all mods.
I really appreciate all of your help, as I have seen the response to similar problems. Thank you!

I am far from a FM-3 expert, but I installed all the FM-3 Zone mods and aligned mine a few months ago, so I have some experience. Did the problem with the tuning eye develop only after you pull/replaced the tubes to check them? If so, I would first suspect a tube pin/socket contact issue and clean them before you do anything else. Does the tuner still function as it did before even without full closure of the tuning eye? I doubt the EMM801 is bad if it is at least lighting up part way.

As far as the FM-3 and sensitivity/selectivity goes, it's just simply not on par with even 70s vintage solid state tuners. After all the modifications to mine sensitivity did improve significantly, but selectivity is still quite poor, and I don't think it will even get better. As far as an indoor antenna goes, I've had the best luck so far with a homemade dipole using speaker wire mounted to a board (stuff I had lying around to try for free). One of these days I plan on installing a real antenna with rotor on the roof to try to get a relatively low power station that's right in the middle of some other more local and powerful signals that the FM-3 can't pull in right now.

All that said, if you are happy with the sound in stock form you will be blown away once you change the PEC modules. The sonic difference in mine from stock to modified/aligned was night and day, with far better upper frequency extension. With a strong signal it is exceptionally quiet and sounds as good or better than any other tuner I have heard.

Thanks for the information, turbotoy! I will start by cleaning the tube sockets - I would not have thought of that. Very encouraging to hear that the FM3zone mods are a great improvement. Yes, I like the sound now, so I can't wait to do the mods. Think I'll deal with the antenna issue after the mods are installed. Could be it will become a non-issue. I'll let you know if the tuning eye problem gets solved.

You are a genius, turbo toy!! I used contact cleaner (without lube) on all the tube sockets and the "eye" works perfectly. I think it sound better also! Thanks again!

By now, you've noticed that I am a lousy typist - sorry!

I'm very glad to hear it was as simple as that! As you continue to work on the tuner just let me know if you have any more questions.

Hi
Although an excellent tuner when aligned properly it is also very sensitive to tinkering. I found that even replacing the same tubes in different sockets had an adverse effect on the alignment. Have you replaced many other parts?
If you have done this then you may need to do the alignment over again. The procedure in the build manual is a good rough guide to get it aligned in most cases but if you can find a signal generator and align the transformers with that you will get superior results.

Some of your transformers have probably have suffered from too many adjustments over the years.I found this to be the most challenging area of alignment.

Sometimes you have to do the alignment two or three times as it is fairly complicated in the sense it has numerous steps that depend on each other and it is demanding to get it just right.
There are two transformers which are often over adjusted in the stereo section and these are the ones you need to check very carefully. They may have suffered from too many adjustments over the years and lost the 10.7 setting that they came with from the factory.
Another tip is that the diodes are are decades old and may be drifting. They are also quite sensitive to heat.
You mentioned you replaced the PEC modules and one of them is very close to these diodes and They may may have suffered some damage from soldering nearby. The diodes are cheap and available from "Mouser" but be careful when replacing them in regards to overheating. Use the heat sink tip of placing an alligator clip on the leads to drain the heat when installing.

As far as an antenna goes; unless you are in a remote area an exotic antenna makes little difference to FM reception even a paper clip on the antenna lead will work fine If there is a reasonably strong signal nearby or if you are less than 100 miles away you should be able to get reception with a simple wire antenna. I would look elsewhere than the antenna.

BTW
make sure you get the transformer adjusting tool because it is very easy to knock little invisible carbon chips off these transformers which fall inside and ruin the adjustment. You may be able to get one for around $7-8 from Chaincey Epperson at the FM# zone site. He still had a few of these about a year ago. I cannot over emphasize this as it occurs invisibly but has a significant effect. Cleaning out the transformers with compressed air may help here as well. Try these tips and if it doesn't work we can go on from there.

I hope Denny can chime in as well he has done a few of these tuners lately and did some admirable custom upgrades to the alignment situation to make it easier.
Good luck
baddog

Thank you baddog, I appreciate all the suggestions. The only thing I have done so far is test the tubes (all tested fine!) and clean the tube sockets, which restored the "eye" tube function and seems to have improved the sensitivity. I am going to order the upgrade, including capacitor board and diodes plus the PEC boards, etc. From FM3Zone. I understand that will make a big improvement. I think the sound is already great, so I am anxious to do these mods. Hopefully, that will eleminate the search for a better antenna. Cleaning the tube sockets seems to have improved the reception already. Again, I do appreciate the help and may well call on you when I do the mods. I am assuming that once the mods are done, re-alignment will be necessary.

Baddog covered most of the bases in terms of tweaking the FM-3,really addressing some of the major issues,but I will say one thing,which I think is important that I have learned over the years,grounding,grounding,and more grounding!!! PC-7,and 8 must have a good electrical connection to the chassis. This is the foundation of the operation of the tuner itself,and affects everything alignment,S/N ration,sensitivity,etc. I would even go so far as drilling holes in both PC-7 and 8 ground planes,and soldering a bus wire to connect both ground planes,making sure not to bridge any solder connection to the signal planes.

Thanks, Denny, for that important suggestion. It looks like I will start the FM-3 mods in about two weeks. I ordered them yesterday and have a Dec 15 ship date. I will keep all these suggestions in the front of my mind - no, I will print them and keep them in front of my nose!

Time now to report my results. I received the parts on Monday and took my time, finishing all the upgrades yesterday. Wow, what a difference: dead quiet, very musical and detailed. For years, I thought my local university classical music station did not have a good signal - boy was I wrong. It now sounds as good as any high powered local FM station. No longer do I need any special antenna. I've heard this tuner described as musical, and now I know why. I am totally pleased with this upgrade and I thank each of you for your suggestions and encouragement. I now have a system that is completely satisfactory to me: this FM-3, my newly upgraded VTA PAS 3, my recently completely built from scratch Stereo 70 with the Welborne mod, older Technics turntable with Denon DL-110 MC cartridge, and finally the Dynaco A-25 speakers. Not high end but very pleasing sound (oh yes, I added the Gold Lion KT66s which are the best tubes I have heard). I value this forum and am learning so much from it.
PS: To be complete, I have a Sony SACD changer, Sony ES cassette recorder and a Revox A-77 Mark IV Dolby reel to reel deck. I'm just old fashioned enough (75 years old) to believe that vinyl and good reel tapes provide the most realistic sound reproduction. Hope I haven't started a war of music sources.
PPS: Chauncey Epperson at FM3 Zone suggested that I not try a re-alignment, since it sounds so good. Is there a short cut alignment in case I need it later?

kygeezer wrote: I'm just old fashioned enough (75 years old) to believe that vinyl and good reel tapes provide the most realistic sound reproduction. Hope I haven't started a war of music sources.

Having attained the "tender" age of 62, I am in agreement. I began my pursuit of "High Fidelity" with a small tube amplifier and turntable in the early 60's, then "progressing" to various solid-state based systems throughout the 70's and 80's. I returned to tubes in the early 90's and have stuck with them ever since. Though I have accumulated a fairly substantial CD collection (nearly 500) which I enjoy, my overall preference is listening to analog recordings from vinyl, R to R tape, or cassette tape (generally in that order). Perhaps this is purely nostalgic, but I tend to think it is how my brain was wired at an early age.

Best Regards,
Charlie

Charlie, I think you're wired CORRECTLY.

Having returned to tubes at around the same time, I've come to the same conclusion that you have. However I can't go back to my Dynaco FM-3 tuners (I have three plus a converted-to-stereo FM-1 which would match the original faceplate on my much-altered PAS-2x) because I live in a fringe reception area for FM. The FM-3 RF section just can't cut it. In fact the RF section of the Dynaco AF-6 I use now is BARELY able to bring in some of the desired stations quietly, and that's after critical tweaking on the bench using a Sound Technology FM generator as a source. A longterm project of mine is to marry the FM detector output of an AF-6 or FM-5 to the portions of the FM-3 that operate at AF: the multiplex decoder and audio section.

I'm glad to hear that you are very happy with the results of the modifications!

I was able to improve the sensitivity of my FM-3 by performing an alignment. When I bought it originally, the seller stated that it had "just been aligned," so I knew someone had already had their fingers in it. However, I first adjusted the bottom slug of T1 to 10.7 MHz using a signal generator I trust, then followed the Dynaco alignment procedure. My general thought is that if you don't do this first and just follow the Dynaco alignment procedure, you are likely going to just take the tuner further OUT of alignment, as the entire procedure is predicated on T1 being set correctly (as it was when it left the factory 50 years ago). If you're happy with how the tuner is performing now, I would agree with Chauncey; leave well enough alonge and just listen!

However, another thing to consider is that a common symptom of being "out of alignment" that I read about was the tendancy for frequency shift over the first 15 minutes or so as the tuner warms up. Before I aligned mine, I would need to adjust the tuner a couple of times in the first 10-15 minutes of use. After the alignment, it's almost dead on within thirty seconds of power-up and no adjustments are required. I just mention this as if I had another FM-3 that exhibited similar drift, I probably would align it.

PS - I'm 32, and have come to the conclusion that the bulk of folks my age have never been exposed to or appricate sound quality like those who are 10+ years older than me.

GP49 wrote:
A longterm project of mine is to marry the FM detector output of an AF-6 or FM-5 to the portions of the FM-3 that operate at AF: the multiplex decoder and audio section.

That sounds like a very interesting project. When you decide to proceed, please keep us posted! BTW, I have an FM3 which I upgraded several years ago. I get fairly decent reception using an indoor dipole (I'm about 20 miles NE of Dallas, TX) although I wonder if having a metal roof might be a negative factor?

Best Regards,
Charlie

Luddite wrote:

GP49 wrote:
A longterm project of mine is to marry the FM detector output of an AF-6 or FM-5 to the portions of the FM-3 that operate at AF: the multiplex decoder and audio section.

That sounds like a very interesting project. When you decide to proceed, please keep us posted! BTW, I have an FM3 which I upgraded several years ago. I get fairly decent reception using an indoor dipole (I'm about 20 miles NE of Dallas, TX) although I wonder if having a metal roof might be a negative factor?
Charlie

No metal roof here. I have a two-story wood frame home with wooden trusses and oriented strand board under asphalt shingles. The oriented strand board does have an aluminum layer on the inside but things really weren't any better with the old roof, which was wooden slats and cedar shakes, no aluminum-layered strand board.

I've tried placing an antenna in a window with little or no improvement, and also moving the setup experimentally to the second floor of the home. The problem is a ridge, about two miles away in the direction of most of the big-city transmitters that are about sixty miles away to begin with. I notice in my car that as soon as I top that ridge, the reception strengthens greatly. Local stations (fortunately, the Bay Area classical station has a satellite transmitter in my area) are OK but the content of most is, shall we say, brainless and repetitive.

To address your observation, turbotoy, I have no drift at all. Turn it on and it stays locked on to the station set with no adjustment needed. I take it that this is a good indication that the tuner is fairly well aligned. I am really enjoying FM for the first time in years.