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185.153.179.62
Hmm, maybe I bit off more than I can chew. I have a cap replacement kit for the FM-3 on the way.
Sure looks like it may still have all original tubes, including the two Telefunkens.
EBAY seller claimed it worked. No way would I plug it in in this condition.
I guess the initial steps will be a follows:
1:boards and components cleanup including disassembly as far as possible.
2:visual inspection of boards, components, wiring,tracings,tubes for heat damage, physical integrity, etc. Visually inspect soldering for quality and integrity.
3:check fuse and order backups :)
4:If all components, boards, wiring, tracing visually look OK, replace line cord.
5:Clean all tube sockets, reseat tubes (after shipping could be loose)
6:Power up slowly on variac, watching tubes and components carefully.
7:if power up indicates no obvious issues, attach antenna and cheap amp and speakers and test basic functionality.
Then think very,carefully about next steps from there...
p.s. I am all ears (pun intended) if anyone has any suggestions. I am NOT trained in electronics and will avoid as far as possible any testing more advanced than what is described in the assembly manual that requires unit to be powered up during testing.
Follow Ups:
I have one that I bought some years back. These are nice when restored and aligned properly. You will need to get a copy of the Service Manual.
Also look into getting some of the upgrades for this FM-3. There is the PEC and Power supply upgrades. I bought and built the PEC kit and power supply kits. The PEC was a big jump in performance, I still need to put the cap board kit in, just enjoying how it sounds with the PEC, Jensen Copper PIO coupling caps and the Takman resistors in the Audio Signal path on output board.
If you keep this tuner, it will need a lot of work cleaning up and then see what you get with the tubes. Also look to see if there in no corroded traces. Also most likely all the those CC resistors are way off due to moisture. Just be very careful when first firing this tuner up.
The FM-3 is a very nice sounding tuner when they are working correctly. I still have my Fisher KM60 Tube tuner and Fisher 200b tube tuners. On the SS side I have the SUMO Charlie, Mitsubishi DA-F20, and the McIntosh MR80.
Are these upgrade kits still available? Can you point me to vendor?
thanks,
LT
all the vintage dust
.
voolston - audiophile by day, music lover by night!
Later Gator,
Dave
This is an excellent point: dust from the days of atmospheric nuclear weapons testing is ever-harder to find; check eBAY completed auctions to see what that stuff's fetching now on the open market!
;)
all the best,
mrh
Well, it's not a tuner, but it is a Dynaco....and it's dusty.
Your interest may vary but the results will be same. (Byrd 2020)
I can't compete with the dead. (Buck W. 2010)
Cowards can't be heroes. (Byrd 2017)
Why don't catfish have kittens? (Moe Howard 1937)
Damn I thought mine was dusty. Yours beats mine by 4X!
enn tee
all the best,
mrh
Oh; just spotted it under all that........!
Shit - sprayed it - was Oven Cleaner..
Clean it up, and I bet you will be fine. If not, I have one in pretty good shape, worked last time I turned it on. I bought it for $50 at a yard sale. I'm located in AZ.
thank you for the offer. I have read that one should always have two of these units for a restoration project. I may be interested in picking up another unit in a few weeks at this project progresses. I will reply here.
If one has a vacuum tube tuner that "works" in an electrical sense, but not in a "radio" sense (i.e., lights up, tubes heat, power supply supplies - without getting hot(!) - audio output puts out ) -- in that the radio does not receive any signal, try removing each tube (one at a time!), cleaning the pins (Q tip and DeOxit, if you like, or just a paper towel), then reseat each tube.
I've "repaired" a number of silent FM tuners just so.
RF and IF circuits are rather precisely tuned (for resonance and oscillation) and, over decades, can go out of whack* for remarkably subtle reasons. Or at least that's my assessment. ;)Try it! Just be careful as there are delicate things in these beasties -- especially (!) 40-plus year old PC boards of at-best moderate quality to start with, and the "main" tuning capacitor, coil/transformer tuning slugs, and trimmers (see also below).
I'd "worry" more about the HV power supply more than anything else, FWIW. I'd also think about replacing capacitors in the signal path (particularly the one or two on the output side), but I'd stay the heck away from doing much of anything in the "radio" side of the circuit (including the IF stages). That said, the Dynaco tuners are meant to be straightforward to align, so they should be a bit more robust than a (nominally) better tuner to amateur troubleshooting.
PS Do be extremely careful cleaning -- especially around that "air variable capacitor" which is the user's primary lifeline, so to speak, to tuning a radio station. Don't spray stuff around it, don't bend the fins, etc.
Apologies to the OP if this is all old hat! :)
____
* "Whack" being, of course, an important concept in VHF circuit design, operation, and troubleshooting. :)
all the best,
mrh
Edits: 06/26/23 06/26/23 06/26/23
not old hat at all, I appreciate the input. I have no formal electronics training. Just kit building experience.
I will confirm the power filter caps are depleted, then do a more thorough cleaning and try and bring it up with my variactor and see if I can get any sound out of it before I again deplete the power caps and replace some of the electrolytics I got from a kit on EBAY.
Hi itman,
I built a FM-3 in 1966, along with a ST-70 and PAS-3. That was the foundation of my first stereo and a great system that I enjoyed for a few years until I sold it to friends prior to a cross country move.
Since it was designed as a kit the manual describes the full alignment procedure. So I suggest finding a copy of the manual and including that in your restoration.
Obviously I'd test all tubes prior to turn on as well.
"In short, you can purchase this record with no fear of its becoming obsolete in the future." Columbia record jacket - 1959.
[[Obviously I'd test all tubes prior to turn on as well.]]
Good point. I'll have to do some research on the tubes so I can at least test for shorts. That's probably all I will be able to do given my knowledge and tools.
The ebay seller claimed it was a working unit, but I never trust such claims. With old electronics, my experience has been that such claims are more often false than true.
I don't see any leaking caps or burn marks anywhere which is more than I can say about a Pioneer F-90 tuner I recently bought from the bay. Again the seller claimed it worked, and it does - except for the intermittent but pretty frequent loud popping sounds after about 1/2 hour of use :)
I opened it up and sure enough looks like every single electrolytic is leaking. So I have a cap replacement kit in transit for that tuner. It does sound great though when not popping :)
I have pdf version of the FM-3 manual and if IIRC the manual does specify use of a VTVM for testing/alignment, which I do not have access to. So I have to figure out what to do about that. I do not have enough knowledge to know if using a modern dvm will work correctly for the testing given how the two devices interact differently with circuitry.
I do have a signal generator and both analog and digital scopes but again,
I'm an untrained novice just learning to understand the theory of the circuits and use of those devices.
Given that the FM-3 appears to have all original tubes I am thinking I can resell without loss if I decide to. So that would be around $200 given the purchase of the tuner and restoration kit. I am not the type to try and make a profit from reselling, way too much hassle to be worth the trouble to me.
Others with more electronics knowledge will hopefully add on here.
I would want to test all tubes before turning it on. Maybe you can find a tech locally to help with that?
As a kit, Dynaco made it as simple as possible. You should be able to do the alignment with just the tuning eye (assuming that tube still functions). Also, VTVMs were what was available when these were new. I don't know why you couldn't use a modern multi-meter.
"In short, you can purchase this record with no fear of its becoming obsolete in the future." Columbia record jacket - 1959.
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