Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Zenith 7H920 AM/FM set 7 tube
#16

here is my down and dirty rendition of shielding a cap.

automotive aluminum sticky back muffler patch repair tape.
a short section of de-soldering wick.


if this does not work well enough, i will move up to something i pulled from some coax cable i laid out next to the cap shown.
that coax braid is aluminum though so i would need to do a tiny crimp to transition in a copper leg.


Attached Files Image(s)
   
#17

Several years ago I saw a DVD on amazon with all the riders info, after nas air crashed I purchased the DVD the quality is the same but trying to find things is a PITA. I do not understand how nas air indxes works but be glad the site is up and running. Looked at your radio on my copy and they look about the same resolution.
#18

all caps replaced and finally i moved on to demo of the filter cap can.

i removed the dual section 80/40 that was installed by the previous repair and measured it.
the aftermarket dual section cap measured as follows:
the 80uf was reading 3uf
the 40uf was initially reading about 10 then to 11 then 13.2, 14.2.... it was charging up but no where near 40

so not only was the original filter caps diagnosed in the past as bad but this aftermarket one is to.

hopefully this ends up being the source of the gargle noise i hear.

your wondering why i did not do the filter caps already... well as the previous post i did a video you can watch,, there was no audible indication that i could hear that is telling me that filter caps were bad... no steady hum or anything.

my plan is to do filter caps as follows....
the 80uf = use 2) 160uf 160v caps in series ,,, OR,,, a single 67uf 160v ---- thoughts?
the 40uf= use 2) 47uf 160v
the last 40uf= use a smaller 47uf 50v or 25v i have on hand.
#19

thank you david!!!
#20

When looking at filter caps for AC/DC sets measure your incoming line voltage (mains voltage) and divide by .707 to get the peak voltage on the line. For North Florida my line voltage runs app. 123.9 most of the time, 123.9 divide by .707 = 175.24 volts. So on AC/DC sets I will use 220-250 volt rated caps with a high ripple current temp rating of 105C. I only want to do this once
#21

Does it do it w/o your outside ant connected?? Also try flipping your non polarized plug around.

When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!

Terry
#22

yes to part 1

i did try that to part 2
#23

On my Z set from the same time period as yours with a four section E-Cap, I used 4  47uf at 250 volts and the set is  good to go. Did you check the resistors as you were replacing the paper caps what % did you have to replace.
#24

just got the filter cap section re-canned up.
i ended up using all 160v because of size,,,, but the 160v ones i used are all 105degC rated which should help with the possible inrush and our modern utility potentials but...... if it does not, i have it set up so that from now on i can come in from the top and replace with some of those fancy shmancy tall skinny reditions that have higher voltages.

i used 1) 160v 100pf & 3) 160v 47uf caps to fill up that short but wider can.

I have not measured resistors yet... visually there are 2 that have a more lacking appearance than others but.... that means nothing. i will make time to do resistors next but at the moment i am hot to trot to see if these filter caps rid myself of the gargle noise.... i am betting yes .

tomorrow i will be firing it back up. i had an unexpected dial string failure so i learned how that installed and discovered i and easily adjust the needle if it happens to be off., otherwise at the least an AM band alignment will be done.

if it all works ok,, then i get to polish the outside and such then put it up on its new spot on my shelf in the garage.
#25

put it all back together and works great.
she cleans up real nice and to be honest,,, the sound out of this thing fills a room!!!!!!!!!
its hard to describe but for a single speaker it sure does sound like stereo to me.

FM works great without a rabbit ear antenna and i have no idea why. ,,, however, fm is broke from 94 on down... no biggie.

here's a pic of it all cleaned up.


Attached Files Image(s)
       
#26

here is a video of it playing with no gargle.

https://www.dropbox.com/s/4f422zs1hg2o1r...7.mp4?dl=0
#27

Can't go wrong with Elton and Kiki Dee!

Looks great.

Paul

Tubetalk1
#28

thank you!

I am at 101 vdc at pin 6 of my rectifier tube,, a lot better than what it was before.

the diagram says i should have 120... perhaps i have a few small issues remaining
#29

ok,, this thread would be worthless if i did not at least entertain a modification due to something i see wrong in the original design as far as looks go.

this set has an interesting feature that when the light comes on,, the yellow translucent plastic rings behind the knobs light up a warm yellow.
currently the light only illuminates "boldly" the right half of the dial indicator & the right knob.

i want to do dual bulbs, one on either side of the of the front of the chassis.

i need to measure what the voltage is to this single huge bulb and has a keyway like an 1156 automotive bulb.
the current bulb is like the old 70's christmas tree lights,, the big glass bulbs and its a single contact but dual elements inside. i think the bulb says its 45watt,, there is no pn on the bulb.
#30

Nice work - and a lovely set Icon_smile

I don't hold with furniture that talks.




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Hickok AC51 tube tester
Absolutely no one is going to reverse engineer that circuit. Even the iron core is missing.RodB — 10:37 AM
IF can wire size and Rubber mounts?
Thanks to both members for your help regarding wire and tuner mtg supports. regards--Johngeorgetownjohn — 09:33 AM
Hickok AC51 tube tester
Note that no power cord, power switch, or power transformer switch are shown. That (along with my experience with full s...DaleHCook — 07:09 AM
IF can wire size and Rubber mounts?
A pair of wire strippers can give you an idea of what the existing gauge of the wire leads are in the IF can, I think it...Arran — 06:07 AM
My last cabinet for this year
Hello Dan, That is really beautiful what great looking radio you have ! I have friends who live in Calgary and the wea...radiorich — 01:51 AM
Philco Predicta Siesta picture over time getting dimmer
I found that the wire insulation was burnt.  The fly back needs corona dope! Why would someone put that there?Platinumblonde36 — 01:09 AM
Philco Predicta Siesta picture over time getting dimmer
This is what it looked like beforePlatinumblonde36 — 01:01 AM
Philco Predicta Siesta picture over time getting dimmer
Platinumblonde36 — 12:58 AM
Philco Predicta Siesta picture over time getting dimmer
Platinumblonde36 — 12:57 AM
Philco Predicta Siesta picture over time getting dimmer
I'm finding some strange things in my set and for the most part it's also original, so I need to start going over everyt...Platinumblonde36 — 12:55 AM

[-]
Who's Online
There are currently 5021 online users. [Complete List]
» 1 Member(s) | 5020 Guest(s)
Avatar

>