[morzh]

Thanks for compliments!
(I did not post the other cap, and it did come out nice but there's nothing special, it is plain Jane aluminum can with aluminum thread and a rubber insulator, so it was easy, the usual).

Oh, and I use a regular pipe cutter to open caps. I usually cut where the groove meets the rest of the cylinder so then when you put them back together it looks kinda natural. When the groove is at the top, I cut the top off; when it's at the bottom, I cut the bottom off.

The only thing I regret, I bought a 1" cutter and I should've bought 1-1/4" one, but for whatever reason the difference was that between 20 bucks and 50 bucks. So when I put the cap in I have to push it in first, so it dents it a bit, but then it's not that critical. Still I think I should get the larger cutter.

[morzh]

Brenda,

Getting back to your remark: I am not sure how I even could run the caps' wires to the connections directly - they are not long enough, except the first one, as you can see the very first connection does in fact have the cap's wire going straight to it but then it is close enough, otherwise they won't reach...unless you have some unusually long-leaded caps. If you do, then there's nothing wrong with running them straight with some heat-shrink for insulation, and it would look quite nicely, I think.

I actually first thought of re-using the wires that were there but then I was not sure what was going on with the insulation, and whether it was in fact insulation or some tar...it was uneven and I even thought I could see the bare wire through it in some spots, so I discarded it and re-wired the whole thing.

[klondike98]

Morzh, +1 on the nice work comments! Here's a pipe cutter that might work and is only about $15.

http://www.amazon.com/Master-Plumber-745...ube+cutter

[morzh]

Bob

Where were you when I squandered 25 smackers on mine? (yes it is Cobalt and has a nice rotating knob and all).

Thanks, Methinks me will order this one.

Mike.

[Eliot Ness]

I agree with the others, you do nice work, very neat and tidy.

I'm not familiar with the chassis on the 90 with pp 45's, but I wonder if the other cap (with aluminum can) originally matched the other capacitor? Kind of like the pair of Mershon caps on other chassis's. I think the Mershon's look very nice polished up, and your first cap looks pretty good too, it'd be nice if you had a matching pair (if that was original).

[morzh]

John

To be honest I am not sure either cap is original.
As you know 90s and 70s could have Mershons in them, but probably not all. The very fact that one (the nice-looking one) says "Sprague" (which I am not sure that it made electrolytics back then, their claim to fame being the Sprague's invention, the paper cap) and another says "Aerovox", and as far as I could observe so far Philco tried to re-label caps, so they actually said "Philco", them both are probably the replacements.

I actually have semi-junk chassis of a 70 which I acquired during the last Kuztown for 15 bucks, speaker included, that does have two unmolested Mershons in it (the patina being black almost, all that crud), but somehow I don't feel like cannibalizing the chassis which is though dirty, does not have rust and underneath is almost spotless clean. I even thought of borrowing a backelite for this 90 and then I felt that pang of remorse....I feel I will just restore it one day and maybe acquire a 70 cabinet.....don't know.

Then again, I am OK with "newer" old aluminum cans as although they are not original, they give a look of "age-appropriate" repair which is much better than those two small Nichicons that were hanging inside the chassis, their wires wrapped in black tape.
After all it is only natural that at some point one could no longer use old wearable parts for repairs, let alone procure the original ones.
I am that "best is enemy of good'nuff" kinda guy.

Oh, well, it will be back to the wall


As for neat and tidy, thanks for complimenting my work, but in all honesty and knowing myself well, I can say that some things I do have patience for and for others I don't, unfiortunately. I will clean a chassis but will not polish it, or paint it. I will not create a dog-bone resistor - I will use a new one. I am reasonably lazy

[morzh]

Well, having said all that, ta-da! (music, lights, drums tremolo) - the witch is de...I mean, the recapping is done!
I will not try to power up tonight, I want to savour the moment and have a beer, plus I want someone at home in case CPR is warranted. Probably tomorrow.

Let the fun begin!

[morzh]

I am about to plug it in to see the transformer voltages.

Before I do it, I eventually took a look at the speaker. I might've written it has been repaired and reconed. Now the field coil which, I think, should be around 3kOhm, is serialized with a resistor and is total of 1.9kOhm, of which the resistor accounts for 1.2kOhm which leaves 700 Ohm for the coil. I do not know whether or not it is sufficient for full power and good quality, the future will tell.
The voice coil is 6.2 Ohm (as I remember the original Philco 20-70-90 coils were about 0.1 - 0.2 Ohm) and the transformer has been replaced. I do not have an audio generator so at this point I cannot reliably measure the turns ratio. Although I think I could use the variac to do this, it's just I do not like variac for this purpose. I need to know the ratio to know whether the transformer was chosen with proper regards to the new voice coil impedance.
In any case it will likely work well enough to get the radio going.

[morzh]

OK, so....

I checked things for shorts, then saw an unbolted AC wire in the plug, then I spent some timer trying to understand why I am not seeing the resistance when measuring between the plug's prongs while having the switch ON - turned out the switch is oxidized and does not conduct well every time to the meter's voltage, but when subjected to the full AC voltage it obviously conducts well (same story with my 20).

Then checked the tubes, then checked the AC voltages of the transformer, then put the 80 in, checked the DC. One output tube did noty have plate voltage - turned out I need to really insert the speaker plug all the way.

Then I turned the volume on, heard the scratch, heard the hum, then put 6" short piece of wire in and heard plenty of stations and of course my local "good time oldies". Loud and clear.
Now, I have distortion on large volume...well, we'll see.

First I need to align it. DC plates' voltages are within reason, so far did not see the grids but I do not think it is even worth seeing as I have no opens in coils and all resistors are good now.
I will probably take a look just for the heck of it.

The alignment, then we'll see what that distortion is all about, but I have an impression that two reasons may be at play: a speaker (bunch of questions - impedance matching, field coil is weak....) and, well, maybe Ron or Terry or LASJHawk could tell me if the detector solutions in 90 are known to be not so great.....at least in 20 they are.
Oh...and maybe the speaker in the open cone down on a piece of cardboard on the table has something to do with it.
It is playing "All you need is love" now.

Anyways, good end of the day, she's singing, ladies and gentlemen, and this is worth a shot of that Lagavulin now.


PS. Yes. Put the speaker on its side - it sounds...great!
I've just earned the second shot.

[morzh]

OK, still some distortion on low...not egregious but worth taking a look at when the alignment is done.

Question: for the 2x45 version, which is the alignment procedure?
There are two in the manual.

http://www.nostalgiaair.org/PagesByModel...013881.pdf

One is on the page 12 and does not specifically show any version, the one on the picture seems to show 2x45 chassis but I can't be too sure.
Also the procedure is a bit ambiguous, like this passage in the "High Frequency Compensator" paragraph. It calls for tuning the receiver to 140 without changing the oscillator setting. The oscillator in the meantime has been tuned to 175kHz from the previous IF adjustment.

the other procedure is on the page 16 and it seems like it is for 1x47 and 2x47 chassis.

Any clarification?

[Mondial]

It appears that the procedure on page 12 is the correct one for the 2- 45's version.

The reason that they say to leave the test oscillator at 175 KHz for the high freq alignment is that they are using the 8th harmonic of the osc to provide the 1400 KHz signal ( 8 x 175 = 1400 ).

I guess that test osc only generated low freq signals so, the 1400 could not be supplied as a fundamental output.

You can of course use your generator to provide 1400 directly, or for greater dial calibration accuracy use a known broadcast station near 1400 to adjust the local osc on freq.

[morzh]

Well, that makes sense, thanks.
For ultimate calibration I use my local Lakewood "Good times oldies" WOBM station which is 1160 kHz.

[klondike98]

Don't know if you've seen it or not but Ed Shutz has a nice two page download of the original 90 operating instructions on his web site. Go to: http://www.renovatedradios.com/downloads.html

[morzh]

So by the "high frequency compensator which one is it? They sometimes say "compensator" and sometimes they say only "high frequency condensor".


PS. OK, got it, it is #49, brought it in.
Let's see further.

PPS. OK, aligned it. It was off, though not too bad.
No off to that distortion. Not sure if I could do too much. Need to start with the transformer ratio which is at this point unknown. The winding wrapper does not say much at all (I am being polite - it has diddly-squat written on it).

[Mondial]

Is the audio only distorted at low volume?

The early 90 used a 24A plate detector which gives a distorted output at low volume settings. There is no AVC, so volume is controlled by setting the bias, and therefore the gain of the RF and IF amp tubes. So when the volume is set low there is a very low level IF signal fed into the control grid of the plate detector tube. The tube is then operating in the nonlinear portion of the tube transfer characteristic near cutoff and therefore the audio output is not a faithful reproduction of the IF signal input. As the volume setting is increased, the IF signal into the detector grid becomes larger and the tube operates on the more linear portion of the grid-plate transfer curve.

Low level distortion is typical of any radio with a plate detector and a manual gain control.