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

Panasonic RE 784A
#1

Greetings all:

I recently was gifted this set...........

https://www.radiomuseum.org/r/panasonic_re_784re78.html

After a replacing capacitors it plays very well on FM no static when tuning, on AM on a station it plays fine when tuning on AM a lot of heavy static between stations. I am perplexed, same tuning capacitor why fine on FM and not on AM? Anyone encounter this scenario? Icon_confused
It is a fine sounding radio and has a nice story behind it being a gift. 

Appreciate your help. 

Paul 


[Image: https://upload.wikimedia.org/wikipedia/c...nt_784.jpg]

Tubetalk1
#2

Well the long answer is this. If it was the tuning cap it's broken down into two parts one AM and the other FM.
[Image: https://upload.wikimedia.org/wikipedia/c...drehko.jpg]
The 11 plates at the front of each section are for the AM tuning and the 2 plates at the rear are for the FM tuning. So it is physically the same cap it's two different sections.
I would suspect that the problem isn't the tuning cap. Were you having this problem the last few days? Could be just noise from weather conditions? Lightening and such.

GL

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
#3

No I have had this issue since I got it. I did not play it till serviced so not sure if it was a long term problem. Not that sensitive on AM either though OK. Very fine on FM though. Perhaps they designed to perform on FM not so much AM.

Was wondering if it could be something in that ferrite antenna? Icon_confused

Paul

Tubetalk1
#4

I would suspect something in the IF or mixer stages perhaps a leaky cap or bad tube. The fm detector is designed to not detect static (change in amplitude) but a shift in frequency. So in the fm mode you shouldn't hear any static. Audio stages are probably ok as you wold hear it in both am and fm if they weren't. In terms of troubleshooting I would use a large value cap (like .1mf) connected to the b- rail and the other end  jumper to the control grid of the a fore mention tubes one by one. Listen to hear when the noise stops then concentrate on that area to find the defect.

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
#5

Great playing radio, unable to find my notes on the one that plays in my work shop. First and only set I have worked on with a 17EW8. If I remember correctly it is used in place of a 12AT7. In reading some were about using the 17EW8 was due to increase in line voltages. I purchased several to use in place of 12AT7. At the time they were cheaper. I did replace the original tube in my set big improvement on both AM&FM. Something about a 3or4 section E Cap? Using a 1N4007, sorry about not being more helpful.
#6

Thanks for the advice, so ****hot and humid up here I have no patience for anything, will listen to FM for now and work on later. 

Thank you gents.

Paul

Tubetalk1
#7

Found my notes the 17EW8 is a sub for 12DT8. The 12DT8 has a internal shield on pin 9, the 12AT7 has a center tap to the heater on pin 9.




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Philco 91 Speaker Replacement
The spider is glued on the cone and so is the voice coil. I think you can use a cotton swab dipped in acetone and carefu...RodB — 02:42 PM
Restoring Philco 37-604C
Yes I saw that. If I knew, I'd probably try to arrange for getting it myself. But I have just got one. Which does not m...morzh — 01:44 PM
Philco 38-2 Automatic Tuning
When you push the lever, you are supposed to rotate the disk to the desired station. Then the magnetic tuning will acqu...morzh — 01:42 PM
Philco 38-2 Automatic Tuning
I figure out the muting from another picture that helped. Now I need to know how the automatic tuning works. When I push...dconant — 12:11 PM
Philco 91 Speaker Replacement
How would I go about removing the spider from the cone?dconant — 12:04 PM
Philco 38-2 Automatic Tuning
Hello, I am having trouble getting my automatic tuning to stay unmuted. If I play with the tuning handle I can get it to...dconant — 10:51 AM
Does anyone make photofinish replacements?
Here’s the link to the DIY photofinish section of our site: klondike98 — 09:46 AM
Delco car radio Peko vibrator converstion issues
Hi Richard, Thx for posting the schematic.  As I remember as a kid, these were great performers for the time, likely...MrFixr55 — 08:56 AM
Delco car radio Peko vibrator converstion issues
hello mr Fixr, The Electro  Powersupply that I am powering the radio with has a huge choke plus a 10,000ufd electrolyti...radiorich — 10:58 PM
Delco car radio Peko vibrator converstion issues
How about putting a choke in the power supply? The big cap was likely an attempt to stabilize the DC. Kids who cre...MrFixr55 — 09:19 PM

[-]
Who's Online
There are currently 3993 online users. [Complete List]
» 1 Member(s) | 3992 Guest(s)
Avatar

>