Steve, there's no such thing as being embarrassed while trying to help. Mine is 4 gang.
I did notice something stupid i did - the third gang was assembled in "reversed". I corrected it but i still get a continuity reading of 1.2 meaning grounded to the chassis. the plates are better aligned and the shaft does not float like it did. Still no reception. 3 Am in the morning work caused the first problem so i'm leaving this for tomorrow. I get obsessed working on this stuff and do more harm than good. I don't know why the 3rd gang is grounded because the other 3 sides are not and i tried to lock it under the rotor shaft, plus the plates are not touching - proved that when i rotate up so top and bottom are not overlapping. Well there's tomorrow. at least that is a problem that had to be fixed. Rich
Just wonder about those padder condensers. They are finicky anyway. Could they have moisture? Had fits with one on a model 70 that I rebuilt. I've learned, aside from parts like caps, sometimes if it ain't broke, don't fix it. I have created more problems from doing this over the years, such as pulling locktal tubes from their sockets to 'clean', and the radio never worked again (yea, probably bad connection on pins), turning "all" to the controls back and forth to clean on an old tv, only to (internally and unwittingly) destroy a wire wound pot, followed by a chain reaction of red hot 5U4G tube, smoke and bye-bye power transformer. I may get reamed for this, but is my 2 cents.
If I could find the place called "Somewhere", I could find "Anything"
Tim
Jesus cried out and said, "Whoever believes in me , believes not in me but in him who sent me" John 12:44
I've been reading the thread and have a few ideas and thoughts about multi gang variable condensers. First, all of your rotor plates from each gang are connected together electrically, there may be a few odd cases where they aren't, but yours ain't one I think. Now these rotor plates connect electrically to the frame of the condenser assembly, most often through a phosphor bronze spring contact, or something akin, often more than one, or one for each gang sometimes. On some cheap sets they actually rely on the bearings for contact, but not yours, I think. So, first thing is check continuity between the frame and the rotor shaft through the whole rotation of the condenser. Next, check for the electronic isolation of each section of stator from the frame, this should be infinite ohms with nothing connected. Next check each section for shorting between the plates through the whole rotation using an analog ohm meter preferably, easier to see. If you find shorting, look to see if the plates are touching anywhere in the rotation. If the short is when the plates are wide open, check the padder for that section. Is the mica good? Try unscrewing it a bit and check continuity again. If it is OK with the padder very loose, but bad when it is nearly closed, you have a bad mica. While it comes to mind, NEVER crank down on a padder, when you feel them bottom that is it, no more. When everything is proper, there should be infinite ohms between the frame and its connected rotor plates, and any of the stator sections, with the condenser assembly out of the circuit. I hope this is of help. I saw you asked these questions early on, so I figured I'd throw in my thoughts. Personally, if they are particularly skanky, I just clean them with a plain Dill's pipe cleaner soaked with alcohol and leave them assembled unless there is some drastic reason to do otherwise. This lets me keep the wet away from the padders and just clean the plates. It takes patience, but it works. I learned long ago, the hard way of course, "If it ain't broke, don't fix it, you may just f*&k it up." By the way, we've all had our tuning condenser woes. The worst I have encountered was on a nice Allied 2515 I picked up off ePay. Some idiot had "installed" a speaker inside the cabinet, which had broken loose at some time; and, with shipping and all I was amazed that only 5 plates of the rotor (which had been left almost fully open) were bent. That took me the better part of a day to fix, but I still didn't have to disassemble the condenser, just gently tweak the plates until they all were perfectly straight and aligned again. Good luck when you get back to it, keep us posted on how things are progressing.
(This post was last modified: 01-27-2016, 09:16 PM by mikethedruid.
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Dennis Carter demonstrated taking a tuning condenser apart on You Tube and then reassembing it, in his case it was from an Airline, likely made by U.S Radio and Television, of about the same era . To reassemble it he used shims that would fit between the rotor and stator plates, like still pieces of paper or plastic of the right thickness. It looked like what he did was put the rotor and stators in and the same time and then dummied in the stators by loosely tightening them down, but you would have to look at the videos again as I am writing from memory here.
Regards
Arran
(This post was last modified: 01-28-2016, 03:59 AM by Arran.)
Mike,
i printed your reply and checked point per point.
my 4 gang stators to frame measure 307.1 / 307.8 / 3.9 / 10.5 ohms not infinite. I rotate the rotor shaft and the measures are consistent. the 3.9 is the High frequency condenser. The picture supports the plates are not touching. The mica is clean and in remarkably good shape (window clean).
When i use the Heathkit signal generator i can walk the tuning squeal up the dial but when i remove the antenna and ground connection i hear nothing from my antenna, maybe static or 'air'.
Morzh your advice is well taken. I have Steve Davis' trim still in the box and the formerly water damaged bottom has been repaired. I also bought some matching Philco 90 grill cloth, so i could focus on the cabinet. This is going to be a great radio someday. I checked my soldering and couldn't find any breaks.
It bothers me that the stations were so strong and clear before all this "cleaning" - i want my radio back.
Enough tonight but tomorrow... i'm a little obsessed (and frustrated). This is what i do for relaxation! Rich
if those measurements are with the condensers out of circuit, you have a shorting problem, probably in the padders. They may be wet if you used water. try rinsing them well with water again, then alcohol, and then, when dry to the touch play a hair dryer on them until well dried. check the resistance again. Dry some more if there is still resistence below the megohm range Of course, if you took the measurements in circuit, I can't really say, and it would depend on the setting of the band switch. Good luck. I hope your micas aren't shot.
(This post was last modified: 01-28-2016, 05:34 PM by mikethedruid.)
If the mica insulators for the trimmers are shot, they may be easily replaced.
Get any "blister pack" of stuff from just about any store - you know, the kind of package that is thin clear plastic.
Cut the plastic into rectangular pieces the same size as the mica insulators.
Use an awl with a piece of wood underneath, and carefully punch a hole in the center of each piece of plastic.
Disassemble each trimmer, making sure everything is dry after they are disassembled. (Do this one trimmer at a time, don't disassemble all four at once.) Don't lose any parts!
Install a piece of plastic in place of a mica sheet and reassemble the trimmer. Repeat this for every trimmer.
It will work fine.
I've done this many times on those older Philco 90, 70 and 20 trimmers.
Thanks for the tip, Ron ! I hadn't thought of that ! My only concern might be heat if the set is left on a long time, but if you have had no problems, then I am sure my fears are groundless. Thanks for the tip ! I'll use it next time I run into this problem. See, you can teach an old dog new tricks !
Quote:my 4 gang stators to frame measure 307.1 / 307.8 / 3.9 / 10.5 ohms not infinite.
These numbers do not look right. The first two sections should read a few hundred K. I see a 490K plus two 51K resistor in series to the chassis. The third section, has two coils and a 51K to ground. The oscillator section has two coils to ground so it will have a low reading.
OK, hold the boat. I see we are talking about an early version 90. The 307 ohms on the first two sections are probably OK as is the third section. However, 10.5 on the oscillator section is not right. It should be 50K or so.
Problem is, when reassembling it i thought i used the washers that came with it. (Still do)
To top it, i broke the hard board that held the stator station of that same gang but epoxyed it with JB Weld >AND< i ensured that it did not effect the performance of the hard board and did not glue the frame and Stator together.
See picture - see the brass 'connector' top to bottom that caused my ground issue - it came this way ! that's a bottom rivet so i believe it is original.
THE REAL FIX is what everyone here kept alluding to, the plates have to be isolated from the stators. The one odd thing, and i still can't understand, that particular stator had a brass (looks like) plate that 'forced' ground when I screw in the stator. Mike is correct, i measured in circuit (didn't know any better) but i know that .9 or 1.2 is connectivity therefore ground! That plate WAS grounded because of the riveted plate. I proved that by completely disconnecting the other screw and it remained grounded.
A couple of weeks ago i when to a estate sale where the former owner keep jars of screws, nails etc. in his workshop. i saw a jar of washers and for $1 thought they'd come in handy. I used one of those washers that is hardboard and de-grounded my stator and plates for that gang! Now it measured 49.5 ohms instead of connectivity/ground.
I turned on the radio, misaligned to $%^& (heck) even so, LOUD and clear! When i aligned i had the BEST reception and sound than before!!!! it is SO clear!
My cleaning spree did something - would i do it again or listen to wiser advice? Right now, i just like the result.
I owe it ALL to you gentlemen who lent your time and talent. You pointed me in the right direction - i just had to figure it out. Look at the picture and tell me is this Plate NORMAL (?) for Philco 90 gangs? if so, what isolates the plates from the frame - i didn't have a hardboard washer with mine.
Thank you ALL so much - you guys are the greatest. Now, on to the cabinet!
Rich
(This post was last modified: 01-28-2016, 11:40 PM by winston763.
Edit Reason: grammar and clarity
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Thanks for the tip, Ron ! I hadn't thought of that ! My only concern might be heat if the set is left on a long time, but if you have had no problems, then I am sure my fears are groundless. Thanks for the tip ! I'll use it next time I run into this problem. See, you can teach an old dog new tricks !
my stator and plates for that gang! Now it measured 49.5 ohms instead of connectivity/ground.