Need some help with a 1934 model 84. Been 50yrs +- since playing with tubes radio or tv. Trying to get this beauty running for my son. Any advice is welcomed.
Turns on ,humms loud as you bring vol up. Checked resistors,some grounds,looks like a few changes,vol control has 2 black plastic leads now attached to ant term and if transformer,and not shure why. Looks like someone lifted a resistor an reconnected it to where it was but with 7 strands of silver wire about 5/16 long! Otherwise im going to continue checking thigs as i can. Found some weird mods any ideas? Then hunt for some needed parts original cord types,grill cloth,grid cap, hopefully finding
(This post was last modified: 08-04-2024, 10:45 PM by Bruce.)
Welcome to the Phorum, Bruce! I would recommend not powering it up again until necessary restoration is done to the chassis. Replace all paper and electrolytic capacitors. Then check resistors for drift and replace any out of spec. Inspect all wiring for cracking or missing insulation. Post some pictures of the chassis and cabinet, if you would. Lots of 'pholks' here to help you along the way. Take care and BE HEALTHY! Gary
"Don't pity the dead, pity the living, above all, those living without love."
Professor Albus Dumbledore
Gary - Westland Michigan
Did you work on this chassis, or is this the way you received the set? It has the appearance that the Bakelite blocks have been rebuilt (new looking Solder blobs). If this is someone else's work, start retracing for possible issues. Either way, good luck! You can access information for your radio in our Philco Radio Library at the bottom of this page under service info. Take care and BE HEALTHY! Gary
"Don't pity the dead, pity the living, above all, those living without love."
Professor Albus Dumbledore
Gary - Westland Michigan
You can replace #29 w/2 10mfd 450v caps. Cut the bottom off of the original cap about 3/4" from the bottom and remove the innards. Fit the new ones inside and wire them in. There's pics around if you need help. Get rid of the large blue cap and the Malory too.
Volume control has been replaced, no big surprise. On #28 you can replace the line bypass cap w/a .015 as stated but the other cap is a filter for the bias voltage. What I do is use a 10mfd 35 or 50v cap +side goes to the chassis - to the ct of the pt. This is what the early model 80 sets used and it provides better filtering in the - leg of the p/s.
The common issues are resistor around the 2nd det being out of spec, If you need to get at #18 you might find it better to drill out the three rivets and lift the covers off. You can get them a good cleaning w/a soft scotch brite/wd-40. The 3 come off as 1. Use 3 sets of 6-32 machine screws,nuts, and lock washers. Pri on #2 and 10. When measuring #2 have the vc full up. When you get there we can talk about rewinding it's easy. Get some 36G magnet wire. Measure the resistance from one of the fat pins on the 80 to pin 2 of the 42 and then pin 3 of the 42 (and 80). Should read 2 or 3K if a lot higher it's bad news.
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
(This post was last modified: 08-07-2024, 06:06 AM by Radioroslyn.)
Thank you for sharing your expertise. I will be starting on this beauty later today an will keep you posted on progress. Where's the best folks to get caps from. I haven't ordered that kind of stuff in years used to visit radio shack for things! Thank you again for the advise ill being using it on the road to recovery for this project.
Regards
Bruce
Tony's used to be Sal's Capacitor Corner. He passes the business on due to medical issues. I haven't ordered through Tony, but Sal's was my go-to source.
Hope this helps. Take care and BE HEALTHY! Gary
"Don't pity the dead, pity the living, above all, those living without love."
Professor Albus Dumbledore
Gary - Westland Michigan
That's interesting it shouldn't matter much as the "volume control" doesn't really control the volume it controls the rf signal coming into the set. I have seen some sets that been modified so that the rf gain is fixed (w/a resistor) and an audio gain control replaced the original. If you trace the wiring around the original will go over to #2. Also the resistance of the pot would be much high if in the audio circuit like 1/2 to 1 meg.
Oh also spec on the resistors is 20%.
Just something to look for when you are replacing parts.
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
(This post was last modified: 08-07-2024, 02:37 PM by Radioroslyn.)
+1 on what the others said. This is an interesting radio, very similar to the 80Jr. These are gutless wonders using only an autodyne convertor (oscillator / mixer) and a regenerative grid leak detector. this is much more primitive than sets using a pentagrid oscillator mixer, an IF amp, diode detector, 1st audio and output tube. However, the performance of this thing is amazing, and they sold these really cheap.
Definitely replace the electrolytic filter caps. They may have been replaced years ago but the replacements may have failed.
The Philco library discusses the Bakelite capacitors and how to hollow and rebuild them.
If you never saw radios of this vintage, volume was not controlled at the input of the 1st AF Stage. Doing so did not come around till AVC. Volume was controlled by a 3 section pot. one section shunted the antenna connection or coil. The other section was used to adjust bias on the Osc Mixer tube.
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
Best Regards,
MrFixr55
Thank you!
Yea seems this one is a weird one,a flea market find @$40.my son fell in love with it when i sent pic to him. It wound up being a " unkown" purchase as far as any history of where it came from an working condition ! I haven't worked on " tube" anything in 50+ years. Then luckily found this forum. 2 immediate responses from members restored my confidence in trying to get this oldie functioning again.radioroslyn an i were on the phone 2 nites ago from 930pm to almost 530am talking shop! Im still in question about a few things. Replacing caps im shure but with which " new" types? I have found diagrams an parts lists,tested resistors already, going to need a few ,my son wants me to keep ot " original" as possible. Now the fun parts, finding parts,and finding folks that can help me relearn the early tube repairs. So any guidance is absolutely greatly appreciated. It seems its been thru several repairs from things ive found. But 90 yrs old its expected. I have been taking pictures as i go pulling bad parts off.,power cord,2 "addon " caps. Pulled the dual 10mfd can . And doing some topside chasis cleaning. Hopefully i can get enough guidance to get it going. Im reading a 688 page book on tube theory an application Relearning early tube information. Book was wrote in 1933.
Thank you for responding,every little bit helps
Regards
Bruce
