Forums :: NEW! Web Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Oct Thu 29, 2020 12:52 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 20 posts ] 
Author Message
 Post subject: Resistor Question
PostPosted: May Thu 21, 2020 9:27 pm 
Member

Joined: Feb Sat 01, 2020 7:08 am
Posts: 64
Location: Riverside, California
To all,

I have a Packard Bell 532 clock radio that both the clock and radio work, but has little to no volume. When I touch the antenna, the reception and sound go up considerably (but still intermittently no sound when I touch). It was re-capped at some point, so assuming this is not the issue. I tried a different antenna, with same results - does this point to a bad resistor?

There are 2 large ones of the same value (looks like 473 ohms) - one is reading over 500 (and case is cracked) and the other is giving no reading at all (infinity?). When I go to order resistors, there's all kinds of different watt readings (0.25, 0.5, 1, 5, 10) - which would I order to replace these?

Please be gentle (lol), I'm very new at this and am in the process of learning the basics by reading articles and posts here. Any good radio repair instruction/course recommendations would be GREATLY appreciated to increase my knowledge.

Thanks in advance.


Attachments:
pb532.jpg
pb532.jpg [ 448.38 KiB | Viewed 1482 times ]
Top
 Profile  
 
 Post subject: Re: Resistor Question
PostPosted: May Thu 21, 2020 10:00 pm 
Member

Joined: Nov Tue 14, 2017 5:09 am
Posts: 3082
Location: Austin, Texas
Those big black things with stripes are capacitors. That type of capacitor is almost always bad and definitely in need of replacement if the case is cracked. I think the value of those is 0.047uF, 200V.

Here's where those two "bumble bee" caps show up on the radio schematic:
Attachment:
packard_bell_532.jpg
packard_bell_532.jpg [ 145.54 KiB | Viewed 1462 times ]

The one marked Noise Filter is not critical to the operation of the radio. It can be cut out for now and replaced later.
The one marked AVC Filter (the lower one in the picture) may be OK if it measures about 3 megohms on your ohmmeter while connected in the radio.
If it measures lower than about 2.5 megohms while connected, it needs replacement.

Oops. I over looked the one at the top of the picture. I think that will be the cap marked as .2uF next to the AVC Filter. The schematic says that may be a different value than .2uF so it may be another of the 0.047uF. That cap couples the radio frequency signals to the metal chassis while providing isolation from the AC power. It should measure infinite ohms on the ohmmeter. Failure will usually not change the radio operation but will be a safety hazard by connecting AC power to the radio chassis.

Jay


Last edited by JnTX on May Thu 21, 2020 10:36 pm, edited 3 times in total.

Top
 Profile  
 
 Post subject: Re: Resistor Question
PostPosted: May Thu 21, 2020 10:07 pm 
Member
User avatar

Joined: Jan Tue 31, 2012 1:55 am
Posts: 14352
Location: Mountains of Mourne. Ireland.
There will be a detailed parts list and much more in...

Sams Photofact (pretty pictures) service manual Set-232 Folder-4 for Teledyne 532
it can be downloaded for free from radiomuseum.org
https://www.radiomuseum.org/r/packard_be_532.html

Pages two to five (descending) in the right/hand scrolling window.


Downloading from radiomuseum.org (non members).
Click a schematic page from the right-hand scrolling window, then again in the main center window.
Each page will be emailed to you immediately.
You can only download three pages a day + up to a maximum of ten every 30 days.

If you experience any downloading difficulties... see this→ viewtopic.php?p=2571007#p2570117
pdf attachments are not visible in junk email folders.

------------

Cover page, view or purchase original hard-copy...

Image
Large image: https://i.ebayimg.com/images/g/FzAAAOSw ... -l1600.jpg
$ https://www.ebay.com/itm/254582648721


Greg.


Top
 Profile  
 
 Post subject: Re: Resistor Question
PostPosted: May Thu 21, 2020 10:08 pm 
Member
User avatar

Joined: Jan Tue 31, 2012 1:55 am
Posts: 14352
Location: Mountains of Mourne. Ireland.
Ride along with John Kopp for a while, he will keep you on the straight and narrow.
viewtopic.php?p=3034114#p3034114
see ✵ ✵ ✵ more→ (restoration video series + signal flow, through a radio + reading a schematic)...
Image

------------

Here are a few informative restoration videos from Paul Carlson.
A young buck out of British Columbia.

Paul has a fair amount of haters on this forum!

BEAUTIFUL 1940's Majestic Radio Receiver Restoration!
Image
Watch 1:33:20 https://www.youtube.com/watch?v=TXKfg5Rdi3U

Electronic Restoration Fun- 1947 Rogers "Chairside" Radio!
Image
Watch 1:59:47 https://www.youtube.com/watch?v=ISbidethQyc

Electronic Restoration Adventure-The Belmont 636 Radio Receiver!
Image
Watch 1:59:57 https://www.youtube.com/watch?v=OWXbdCz-AiY

------------

Saving Youtube videos:
https://bitdownloader.com/youtube-video-downloader
add .mp4 to your downloaded file name.
Image
Greg.


Top
 Profile  
 
 Post subject: Re: Resistor Question
PostPosted: May Thu 21, 2020 10:20 pm 
Member
User avatar

Joined: Jan Tue 31, 2012 1:55 am
Posts: 14352
Location: Mountains of Mourne. Ireland.
"Black Beauties" aka Bumblebees...
viewtopic.php?p=3173979#p3173979

:) Greg.


Top
 Profile  
 
 Post subject: Re: Resistor Question
PostPosted: May Thu 21, 2020 10:45 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 36228
Location: SoCal, 91387
The dual value capacitors in the large red container at the top of the scan need to be replaced. You can use two discrete caps. I would guess that might be the main reason volume is so low, but definitely change out the cracked component as well.

You can leave the container in place, and simply cut the black lead (negative) from the right side, and the two leads coming out of the left side. Those can each connect to the positive side of each replacement, and then tie their negatives together and connect to the black lead.

_________________
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins/////////////////////////


Top
 Profile  
 
 Post subject: Re: Resistor Question
PostPosted: May Thu 21, 2020 10:57 pm 
Member

Joined: Jun Sat 15, 2019 7:43 pm
Posts: 950
egg wrote:
"Black Beauties" aka Bumblebees...
https://antiqueradios.com/forums/viewto ... 9#p3173979

:) Greg.

Nope, Bumblebees and Black Beautys are different. Bumblebees are paper in oil, Black Beautys can be paper or poly

DM


Top
 Profile  
 
 Post subject: Re: Resistor Question
PostPosted: May Fri 22, 2020 12:05 am 
Member

Joined: Feb Sat 01, 2020 7:08 am
Posts: 64
Location: Riverside, California
Good stuff! I did not realize those were capacitors - just downloaded Capacitor color charts for the future. I do have a couple of 0.47's, so I'll swap those out tonight.

I figured the filter caps to be good since there was no hum when powered on. I'm not sure when it was replaced, but from the looks of the other capacitors 60's or 70's? Either way, will only be out a few bucks if I change the electrolytics. I have a 50/50 German replacement that I can test with.

That .2 at the bottom connects to chassis ground, I've heard that a bad ground can cause antenna/reception issues (?). Either way, I have some direction - I'll post back with results.

I really gotta get better at this! Thanks for the help (and I'll be watching YouTube tonight for sure).


Top
 Profile  
 
 Post subject: Re: Resistor Question
PostPosted: May Fri 22, 2020 12:55 am 
Member
User avatar

Joined: Jan Tue 31, 2012 1:55 am
Posts: 14352
Location: Mountains of Mourne. Ireland.
I have no intention of arguing with you.

But... I'll tell you one thing - - they all make the same noise when they hit the trash can. lol


Greg.


Top
 Profile  
 
 Post subject: Re: Resistor Question
PostPosted: May Fri 22, 2020 1:14 am 
Member

Joined: Aug Fri 30, 2019 11:36 pm
Posts: 94
Location: Tucson, Arizona, 85704
Quote:
Paul has a fair amount of haters on this forum!


Why, is this? No flaming, please, I'm just asking an innocent question.

_________________
"No Humming" - sign in a Capacitor factory.


Top
 Profile  
 
 Post subject: Re: Resistor Question
PostPosted: May Fri 22, 2020 1:17 am 
Member
User avatar

Joined: Jan Tue 31, 2012 1:55 am
Posts: 14352
Location: Mountains of Mourne. Ireland.
viewtopic.php?p=2951742#p2951742

Greg.


Top
 Profile  
 
 Post subject: Re: Resistor Question
PostPosted: May Fri 22, 2020 2:02 am 
Member

Joined: Aug Fri 30, 2019 11:36 pm
Posts: 94
Location: Tucson, Arizona, 85704
Quote:
It was mostly about capacitors....


Well, we must admit, for many years Capacitors have given us much grief.. :lol:

BTW, I do enjoy Carlson's Videos.

_________________
"No Humming" - sign in a Capacitor factory.


Top
 Profile  
 
 Post subject: Re: Resistor Question
PostPosted: May Fri 22, 2020 2:15 am 
Member
User avatar

Joined: Jan Tue 31, 2012 1:55 am
Posts: 14352
Location: Mountains of Mourne. Ireland.
Some of the biggest bust-ups here over the years have been about capacitors. Crazy... or what!

Yes, I enjoy Paul's videos and his contribution to the world of hobby radio repair.
He's a smart cookie - - just don't buy anything that he is selling - - you don't need it - - unless you want more toys. lol


Greg.


Top
 Profile  
 
 Post subject: Re: Resistor Question
PostPosted: May Fri 22, 2020 2:57 am 
Member

Joined: Feb Sat 01, 2020 7:08 am
Posts: 64
Location: Riverside, California
Attachment:
20200521_112424 (2).jpg
20200521_112424 (2).jpg [ 102.17 KiB | Viewed 1376 times ]
Same question...different radio.

Is this a capacitor or resistor? Not as big as the Packard Bell, but bigger than the resistors. (GE 515). Thanks


Top
 Profile  
 
 Post subject: Re: Resistor Question
PostPosted: May Fri 22, 2020 4:22 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 36228
Location: SoCal, 91387
That's a 1K resistor. You can differentiate similar looking capacitors by the extra number of bands on them. 20% resistors only have 3.

_________________
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins/////////////////////////


Top
 Profile  
 
 Post subject: Re: Resistor Question
PostPosted: May Fri 22, 2020 5:54 am 
Member

Joined: Feb Sat 01, 2020 7:08 am
Posts: 64
Location: Riverside, California
Thanks for resistor help

I replaced both 0.47 caps and filter caps with no change - reception only when I hold the antenna (still with low volume). I couldn't replace the 0.2 cap, didn't have one. I did connect a jumper wire and bypassed the cap with no change (left the cap inline). I've reached the limit of my knowledge base and have to call it quits for tonight. Thank for the advice so far, but might have to get my daughter a clock radio at Target!


Top
 Profile  
 
 Post subject: Re: Resistor Question
PostPosted: May Fri 22, 2020 7:37 am 
Member

Joined: Jan Tue 16, 2007 7:02 am
Posts: 3923
Location: Lexington, KY USA
I replaced both 0.47 caps ...

But there are no 0.47uF caps on the schematic nor visible in the photos to be replaced. An AVC cap that's 10X as large may make for pretty slow AVC action.

Did anyone point out that the "Noise Filter" 0.05 uF part really should be a safety rated component, since it's across the AC power line?
So should the B minus to chassis capacitor.

Ted


Top
 Profile  
 
 Post subject: Re: Resistor Question
PostPosted: May Fri 22, 2020 1:17 pm 
Moderator
User avatar

Joined: Feb Sun 01, 2009 2:56 pm
Posts: 11468
Location: Victoria, Australia
On caps that should be line caps and caps in general. If you can measure the resistance of a non polarised cap on an ordinary ohm meter, its a dud. Limit for a non polarised decoupling cap is not under 50Meg. My spec. is if it leaks at its rated voltage, or lower, it can only get worse & its a dud

Marc


Top
 Profile  
 
 Post subject: Re: Resistor Question
PostPosted: May Fri 22, 2020 6:17 pm 
Member

Joined: Feb Sat 01, 2020 7:08 am
Posts: 64
Location: Riverside, California
Ted: Typo...my bad...I meant .047 caps (listed as .05 on the schematic).

It looks like the other capacitors are original and listed on the Photofact. I did research and RMC label = Mallory ceramic - do ceramic capacitors go bad and need replaced? I've read mixed opinions on here about this. Looks like there's two .01mF; two .002mF; one .0005mF (technically .00047) and one .005.

I'm also going through resistors and finding a few out of spec.


Top
 Profile  
 
 Post subject: Re: Resistor Question
PostPosted: May Fri 22, 2020 8:45 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 36228
Location: SoCal, 91387
Ceramic capacitors generally do not go bad, although Zenith produced some back in the day that were prone to failure. They can be easily identified though, as Zenith emblazoned their name in yellow on them.

Three band 20% tolerance resistors are fine as long as they measure in that range, so a 1K can read up to 1200 ohms and still be considered useable.

Four band resistors, with the last being either silver for 10% or gold for 5%, need to be within those limits.

_________________
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins/////////////////////////


Top
 Profile  
 
Post New Topic Post Reply  [ 20 posts ]  Moderators: Norm Leal, Marcc

All times are UTC [ DST ]


Who is online

Users browsing this forum: bob_u, Greggshere, Jimmler, Tbone and 28 guests



Search for:
Jump to:  


































-->


Privacy Policy :: Powered by phpBB