Philco 38-690 electronics restoration. - Printable Version
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RE: Philco 38-690 electronics restoration. - morzh - 04-17-2017
Looking at the diagrams and the available photos of other folks I see the tubular electrolytics that are present in my chassis are not there normally, so they were likely added at a repair facility (I can say, added very neatly so I think it might've been an authorized shop though the caps are not Philco but just maybe Philco no longer made those that would just fit). The single cap I could see on other photos are the on on top.
So no need to buy tubulars. Will get by can electrolytics when rebuilding the power/amp chassis later.
RE: Philco 38-690 electronics restoration. - morzh - 04-18-2017
These caps have been restuffed.
I reused the wax. The wax darkens after re-melt but still look natural, plus there are darker wax used sometimes.
I put some hot glue first and then melt the wax on top of it when it solidifies.
These have not been changed yet.
RE: Philco 38-690 electronics restoration. - klondike98 - 04-18-2017
Looks good Mike!
RE: Philco 38-690 electronics restoration. - Nathan Slingerland - 04-18-2017
Beautiful job - as original looking as it gets!
RE: Philco 38-690 electronics restoration. - morzh - 04-23-2017
Did left and right sides of the chassis, now the only caps left are in the RF chassis but there are few and they are well within access.
Changed 3 resistors - most are within tolerance.
Different caps use different wax and some use light colored one that doesn't melt as quick as the brown one and then foams a lot.
Not going fast but the wax re-use slows down the process.
RE: Philco 38-690 electronics restoration. - morzh - 04-29-2017
With the exception of the single electrolytic cap on the main chassis I have finished recap of it today.
Waiting for the sch to come from Chuck as I want to figure how the electrolytics are connected through the cable and to disconnect those axial electrolytics I keep for now as the place markers.
Today there was the central part, which is also the RF chassis, and it has three caps encased into a cylindrical screen, which in 2 out of 3 cases made the replacement a bit complicated.
Here is how it went.
This is the cap in the screen I am talking about. Nothing special: the wire soldered to the screen is easily unsoldered and the cap, after a little warming up with a heat gun to loosen the wax (6-7 seconds) is pulled out.
Then restuffed, potted and put right back. E-Z.
Now comes the second one. This is sandwiched between the two chassis plates separating the RF chassis into sections. I could not pull it out as the space is not enough.
Luckily, the split in the cylinder and the fact that the plates flex a little allowed me to tilt the cap at the angle enough to pull it out.
Then I put the cardboard protection disks I cut to size inside the cap after gutting it,
RE: Philco 38-690 electronics restoration. - morzh - 04-29-2017
...and pot it with hot glue first, and then with the remaining original wax.
Put it back
And solder top and bottom terminals.
Done.
But wait....there is the last one. And it is hindered with more stuff than just the chassis plates, let alone sitting deeper inside and close to the corner.
RE: Philco 38-690 electronics restoration. - morzh - 04-29-2017
It is under the stiffness bracket. And a wire goes over it which is pretty taut. And the slit in the cylinder looks towards the wall. As if all before was not enough.
So we start from removing the bracket. The screws are not well accessible but luckily they are 1) standard Philco hex and 2) I just happened to have a small tiny adjustable wrench in my very own pocket.
The bracket's out.
RE: Philco 38-690 electronics restoration. - morzh - 04-29-2017
And the wire that was going over, very taut, is unsoldered.
So its end over the cap can me moved.
Then (drum roll, please!) a bend of the cap and a bend of the plate above and....the cap's out!
Gutted. Potted.
And (with some difficulties...it is always easier to pull it out then to push it in) it is back in it's cilynder.
And the wire is soldered back.
Then the bracket is put back. Putting screws back was a challenge...good thing I have small hands.
Whew!
RE: Philco 38-690 electronics restoration. - morzh - 04-29-2017
Some views after the recap.
RE: Philco 38-690 electronics restoration. - jcassity - 04-30-2017
wait,, are you kidding me!
this is how new i am,, to this stuff....
your actually inserting a modern cap inside the old cap container?
mega bow to you sir!
RE: Philco 38-690 electronics restoration. - jcassity - 04-30-2017
and,, there are no caps inside this?????????
RE: Philco 38-690 electronics restoration. - klondike98 - 04-30-2017
yes, morzh stuffed new caps inside the old shell of the paper cap to keep the original look. This restuffing technique takes a fair amount of extra work so most folks for most radios don't do it. you warm up the old cap and pull the guts out of it leaving the paper/cardboard tube. A new cap is inserted and then refilled with something like hot glue. Some use old was pulled from old caps or new wax with the brown coloration.
RE: Philco 38-690 electronics restoration. - morzh - 04-30-2017
Jcassity
Yes, restuffing is the main time consumer.
And this is not the limit: some, like Steve or Russ replicate resistors (since restuffing not possible). Theirs is fully authentic look.
In the backelite block, no, those are inductances, not caps. Not to be touched.
PS. There's nothing wrong with simply replacing the parts with modern ones. Still brings the radio back to life. No one really looks under the hood. Everyone picks one's own acceptable level of suffering
PPS. To see a more painful recap, look here
http://philcoradio.com/phorum/showthread.php?tid=16039&page=2
RE: Philco 38-690 electronics restoration. - Kenneth F. Besso Jr. - 04-30-2017
OK,,,MIKE (Morzh),,,,why are these caps in Metal shields ???? Is it the same as a tube shield ??? To prevent interference on thee Coils???? Or is it just to keep them from getting to close to thee coils (Stable),, ??,,Thank You ,,in advance --CHEERS