While it has a plain-Jane appearance and is perhaps lacking some convenience features like a bandwidth switch or muting, this tuner that came out in 1964–when tweaked like we know how–sounds surprisingly good, better than it should. It’s slightly warm and provokes no listener fatigue. You can get caught up in the music for hours.
After restoring several FM-3 stereo tuners for ourselves and friends while learning and noting all the tips and tricks, we decided to offer the service to anyone. (We’ll work on the mono FM-1, too. Please inquire.)
There are thousands of units out there, and many would benefit from a basic tuneup, others a complete restoration. While this tuner was designed to be aligned without any special equipment (other than optionally a VTVM), there’s no rule against it, and we get better results, especially on the IF stages and front end adjustments. We use a Leader 3236 synthesized AM/FM stereo signal generator, a restored Eico 249 VTVM, and a QuantAsylum QA403 audio analyzer. The IF alignment is standard (not swept). For parts, we use top-quality audio-grade capacitors and resistors from Nichicon, Panasonic, Wima, TDK, and Vishay.
We offer several options. You can choose any you want. That said, Option A usually is the best place to start, with Option B a perfect and natural complement.
Option A $99
Inspection, current draw and voltage checks, tube testing and replacement (if required), complete alignment (IF, discriminator, front end, multiplex board), switch cleaning. Includes one-hour run-in. (We also do a check for bad resistors and replace any found.)
In many cases, unless yours has a bad hum, this option gets your FM-3 running well and sounding good. Tubes replaced, if required, at modest extra cost.
Don’t ignore your tubes! They’re all important, but the 6AT8A and 6BL8 tubes are notoriously flaky, and if they aren’t working right, your tuner certainly isn’t working right. Ideally, the audio out tube V72A (12AX7) triodes should be balanced to 20% or better.
For an additional $19 we’ll use our QuantAsylum QA403 audio analyzer to adjust the discriminator to lowest distortion. Typically, the standard method achieves about 0.9% THD+N. Tweaking with the QA403 gets it down about 22% or so to around 0.70%. Otherwise, we’ll use the standard Dynaco VTVM method.
Alignment only: If you’re confident in your tubes and want a full alignment only, that’s $69.
Why Have a Tech Align a Tuner Designed for User Alignment? Yes, the FM-3 was designed to be user-aligned with no or minimal instruments, and that generally worked well back in the day when the FM dial was sparsely populated and still had some mono stations, but a precise and expensive modern FM stereo signal generator like ours produces far more accurate results under modern conditions. For aligning the IF stages, the Dynaco method requires you to find a quiet area between stations, which can be a challenge depending on your location. Dynaco also calls for a mono station for aligning the discriminator and weak signals for much of the front end adjustments (which directly affect sensitivity). Again, nearly impossible to find. And, IF transformers T2-T4 slave off T1 for the IF stages alignment. How would you know if your T1 is set at 10.7 MHz in the first place? Lots of them have been “tweaked” over the years. That would throw off the entire IF alignment.
Our alignment procedure neutralizes all these challenges.
Your FM-3 will find more stations, with higher fidelity and better stereo separation.
Stereo Separation Test: For an additional $19 we’ll perform an IEEE/IHF stereo separation test at 1,000 Hz. This is done at the end of the alignment, right after the MPX board adjustments. You’ll get all the test results details.
The following options are priced separately from Option A, which is strongly recommended after completion of any option below:
Option B $159
Replacement of all electrolytic capacitors and four key film caps (C29, C31, C82, C83) and resistor upgrade (R2, R3, R11, R13 to 3W metal oxide, R38 to metal oxide). If your unit has a noticeable hum or you’re a critical listener, you’ll want this option. We use top-shelf parts.
Your original four-section electrolytic filter capacitor can is retained for cosmetics and the new audio-quality capacitors attached neatly and securely at the chassis bottom. (For a new replacement filter capacitor can, add $40 and make a notation on the order form.) R38 is at the original values but replaced with a quieter metal oxide type. The other four resistors are at their original resistance values but replaced with higher wattage ratings, as the originals often get hot and scorch the circuit board.
C29, C31, C82, and C83 are replaced with fresh audio-grade polypropylene caps. Additional details on C82 and C83 are described below in Option C.
Option C $89
Replacement of all eight stereo multiplex board film capacitors with top-shelf audio-grade polypropylene capacitors. This option results in lower noise in stereo and better stereo separation. C82 and C83 are increased a bit from 0.1uF to 0.47uF for better bass response and impedance matching to modern amplifiers. If you want the original values or an increase to 1 uF, we can do that, too. (We’re purists and don’t consider changing the values of C82 and C83 a modification as much as an adjustment.)
Option D $109
Replacement of PEC-1 and PEC-2 modules (Dynaco part 555001). This corrects a design error in the de-emphasis circuit that depresses the upper frequencies. With this option you’ll get a more neutral tonal balance. Again, not a modification–more a correction. We didn’t invent it. It’s been around now for years. The main parts used are expensive, close-tolerance mica capacitors, and building the boards is time-intensive, so this option is somewhat costly. We also replace the PC-8 PEC module (Dynaco part 555004), which is less audibly critical than the other PEC modules, but it’s getting old, and it’s a good idea to replace it while we’re already in there.
How to Send Your Unit
Shipping an FM-3 is simple and inexpensive by ground. It’s fairly small and light, nothing like a typical AM/FM stereo receiver. See packing details below.
Go to the Dynaco FM-3 Service Order Form tab on the home page, print out the form, and send it with your tuner. Please make sure to review the options carefully in the section above. Feel free to email at any time if you have questions.
Some Details to Keep in Mind
While we keep some spare Dynaco FM-3 parts around and can do basic troubleshooting, this service is intended for tuners that will power up or were working in the past and put up in the closet or down in the basement. We do have spare knobs, faceplates, covers, tubes, and even some power transformers. If in doubt, please contact us before sending.
Unrestored FM-3s are available commonly in working condition with all the tubes for about $80-$120 on the Web, far less at garage sales. Go for a factory-wired unit if possible, which has rivet fasteners on the back panel and normally a silver serial number sticker back there, too.
Packing
No need to remove tubes or tube shields. The best way to pack is to wrap the entire unit in a clean soft cloth or place it in a clean plastic bag and then wrap it in bubble wrap and then place the wrapped tuner in a box, filling up the gaps on all sides and top and bottom with wadded newspaper or wrapping paper, and tape it shut. Coil the power cord loosely and put a rubber band around it, and tuck the cord out of the way near the chassis back. Some extra bubble wrap or padding on the front panel side is a good idea, too. Then, place that box into a larger box (minimum 2″ larger on all sides) with wadded newsprint, bubble wrap or other padding all around–top, sides, and bottom–for cushioning, and tape it shut. Everything should be snug, but not super-tight.
Payment
We accept Zelle (preferred) or PayPal, but we can accept personal checks.
Warranty
Our parts and labor are warranted for 30 days. If something comes up within 30 days, contact us with a description of the problem. If additional work is required, owner is responsible for return shipping. We’ll cover shipping back to you.
Turn-Around Time
We can usually complete your FM-3 in about three days. We keep a good supply of standard parts, but if out-of-stock parts are required, that adds about five days because of parts shipping time to us.
Notable FM-1s and FM-3s We’ve Worked On Recently
