SP-600 Help Play Find The Vanished Components!?!?

[WBear2GCR]

Ok, so usually one does not look to identify every single component in a receiver like the
SP-600. Unless, of course, you are doing a complete chassis strip and rebuild, OR there's a failure
that requires checking said part(s).

That's what we've got here.
Calling Sherlock Holmes!

Power supply.
First off, what the heck is up with running 6.3v filaments off a secondary marked 7.5volts?
Two of them!
But ok, I can live with that (I guess) since there must be voltage drop somewhere.

And, yes, sure enough, there in the sketch-a-matic are some chokes with a DCR of ~2.5ohms,
right after the windings.

WHERE THE HECK ARE THEY IN THE ACTUAL CHASSIS???

No reference to them in any manual I have that shows part location - that I can find.
(can't seem to locate the caps either!)

                    _-_-bear

Bad copy of that section included for your approval.

[Ed - N3LHB]

Not currently having a SP600, my guess is that the inductors are under the chassis as their value is in microhenrys. Look for a resistor-like component with a very low resistance value. 

[wa2fxm]

Bear,

Just had my SP-600 on the bench yesterday. Fortunately I wasn't working on the innards, just a broken wire on an outboarded audio output transformer. But according to the manual I have (SP-600-JX Issue 4) your chokes are L48 and L49 in the RF Platform. With the RF module standing on it's side with V1 towards the bottom. L48 is just south of V1 and L49 is just above V5 at the top of the module. That's according to the very ratty photo of the RF Platform that's in my manual.

WA2FXM Mark

[WBear2GCR]

Oh, now that is interesting.
Thanks, will have to look for them on the RF Deck!

Now, how to get to them!

Thanks Mark!

And Ed, yes, was expecting a "resistor" looking choke... just couldn't find it!


                       _-_-

[kb2vxa]

No need to growl unless you found them already in an unreachable location. Just look for a green tubular device the diameter of a 1W carbon comp resistor only 5 times longer with a resistor color code and axial leads. The clincher is the DCR test, they read less than 1 ohm. http://firetrucksandequipment.tpub.com/TM-9-254/css/TM-9-254_220.htm for the color code.

[WBear2GCR]

The manual specs them at ~25ohm DCR, iirc...