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Harman Kardon FA 3000x FM tuner diagnosis questions

Ric Harris

Ric Harris

Active Member
I picked up this old receiver and with the aid of a variac a dim bulb tester and some solid advice I got it up and running. At least amplifier wise. The tuner however is not working. i have no idea if it's within the tuner its self or if there's an issue with the signal reaching the amp.
I am uncertain where the test point may be and whether tubes are a likely or unlikely cause.
Point to point wiring may look simple to the trained eye but for me it looks confusing. IMG_0064.JPG IMG_0067.JPG

I'll capture the underside tomorrow.
 
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I cranked the volume up pretty much all the way and not a sound. I changed the afc settings, tried fm mono and nothing. I'm going bypass the external antenna input and attach it where it enters the variable cap unit. I doubt that will be fruitful but it needs to be crossed off the list. I blew some air inside the variable cap but it's enclosed and I doubt it's gunked up and if it was oxidized you'd think I'd get a harsh snap crackle pop. The whole time I've monkeyed with it I've had the tuner set near 104.5 WAXX. That station's signal is so strong it can be tuned in with the poorest of tuners from 100 miles in any direction. In fact I've used a paper clip for a antenna and got 5 bars on my old JVC in the basement it's so strong. It's old school country and I despise it but it sure is handy for testing.
 
If you get no sound at all, there is likely a bad tube, or no voltage to the tuner, I have to see a schematic to be more specific.If it was a signal problem, there would be a hissing sound.Does it have a FM mute switch
 
As the chassis looks dirty and sports some corrosion,I would suspect a bad tube-to-socket contact.

First,remove all of the tube shields and verify that every socket contains the appropriate tube type.Then,check that every tubes heater is lit. If so,remove each tube individually,spray the socket with a quality non-residue cleaner,and while the cleaner is still wet insert and remove the tube several times.Do this for ALL of the tubes.
Wait until all cleaner has evaporated before giving it a try. Also, perform the same cleaning on the input selector switch. You will need to do a much more thorough going over later,but try these steps for now.
 
I've been somewhat out of commission thanks to a kid texting while driving20170913_181010.jpg

Yeah my rusty work car is no more.
As for the tube sockets being gunked up I'll give them a good cleaning as for the tubes every one I looked at lit up. As for FM mute there is none. The selector control was the first thing I cleaned followed by all the pots. I will say that if I have the volume cranked I will get an occasional crackle but it doesn't seem to matter where on the dial it is. I have another tube radio that is also challenged but it will crackle most where some of the stronger broadcast signals are. I'll clean up the tube sockets and check to make sure the right tubes are in the right places and see where we get with that.

It would be nice to get it going so when my next project an Heathkit AR-1500 arrives I can jump into that.
 
A bottom pic of the tuner area would be helpful. C 30 and C31 would be a good place to input a signal to test up to the function switch. In the past I had trouble with the 6C9 tube in a tuner I had, it is a 10 pin tube.
 
I think I may have the answer> There are two 6EJ7 tubes and one gets real warm while the other is not very warm at all. Both light up inside but the cooler one isn't real bright. I recently picked up a Westinghouse HiFi that to has some FM issues but it may have a 6EJ7 EF184 or a 6P9 I can steal just to find out if that's the source of the problem. I can't imagine a 6EJ7 is neither rare or spendy so if it works I'll snipe one on ebay. Being my Packers played Thursday and the lawn is mowed will have time to tinker tomorrow and with any luck that old Westinghouse will have one to borrow. I bought that Westinghouse because it has a simple single ended 6V6GTA amp that works pretty well. I'm hoping to turn it into an Acoustic Guitar Amp for my son. His Marshall is not suited for acoustic and it would be a fun gift to give him a homespun, built by Dad, Amp for X-mas.
 
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