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40-180 Restoration First Steps Question
#1

Thanks to Rod, I've got a replacement transformer. 

Before I do anything else, I wanted to share my plan of attack and see if I'm on the correct path, way off course, etc.

- Replace the power cord with polarized cord, inline fuse on hotline wired to the switch (done)
- Check tube heaters for shorts (done, actually ordered some backups from findatube.com per Rod's recommendation)
- Test speaker resistance (done)
- Will replace the 0.01uF caps in the bakelite with safety caps
- Replace the electrolytics
- Visual inspection to replace other obvious issues (cracked wires, other caps, bizarre frankenstein repairs
- Connect replacement transformer
- Power up through Variac

Appreciate all you all's expertise and input.
#2

Soumds right.

Oh, the tube's heaters usually fail open. Not short. Tube itself can have the heater shorted to other things, or the other things shorted to each other, but the heater, it usually either good or open.

People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
#3

Thanks!
#4

How did you remember all that?
Suggestion: If you find wiring with cracked insulation you may get by with unsoldering one end, clean the insulation off the wire with long nose pliers, slide some spaghetti insulation or heat shrink over the wire then re-solder the connection.

Take care connecting the input filter cap, part 61, the negative is not grounded but connected to the center tap of the power transformer.

Mike - He didn't waste any time!
#5

Good strategic planning!

People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
#6

Regarding short circuits between tube elements other then a rectifier I have never run into a short that caused catastrophic damage in a radio. Whenever I have encountered a shorted tube it's usually a short between the grids, which are close together, and somewhat delicate, on occasion a heater to cathode short, which causes hum, but that's more common in power output tubes in AC/DC sets, like a 50B5/50C5. Most tube failures are either open heaters/filaments, poor emission, gas, or the odd one can become intermittent.
Regards
Arran
#7

Rod - genius call on regarding the cracked wire method you suggest. Thanks for that! I need to look closer at the schematic re: 61 - appreciate the watch out.

Arran - thanks for the info on tube failure/performance. So much to learn!
#8

Progress to date -

Took the old caps out of the Bakelite (no small task). Upgraded with safety caps.

Reconnected transformer primary. All looked good
Next up Electrolytic caps (triple checking polarity!). Previous work placed new electrolytic and tied into the old original cap. Going to disconnect all that and start fresh with new caps/connections.
#9

Hi TFonzart,

Sounds like you are definitely on the right track! You are right in redoing electrolytics. It was never a good idea to "bridge" the old caps with new ones, as the old wet electrolytics tended to short. The dry ones can short also.

Congrats on progress so far and good luck! Keep us posted!

"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
"Let us begin to do good"- St. Francis

Best Regards, 

MrFixr55
#10

Hi Tfonzart.
Please check your email. I didn't have a way to send you my tutorial on how to easily rebuild those Bakelite blocks. No mystery or worry about it being so difficult or some black magic art. Icon_smile No mess no fuss and after doing a couple you can do them in 3-4 minutes each.

 I'll try and attach it here.  I may have uploaded it here before years ago, in a 'files' section on the site.

 If anyone has any questions please give me a shout.

BTW, the very first console I bought when I seriously got into radios was the venerable 40-180. Still have it and 2 other unrestored ones in storage.
        ERROR Attachment is too large to upload. I'll look for another way.
Take care everyone!
Gary Maker. (Rabbitt)
#11

Thanks MrFixr!
Will do!
#12

Gary,
Wow thanks for the detailed info in the email.
Sent you a reply so you can attach the PDF direct to my email.
Thanks again !
#13

Hello tfonzart ,
Once you get doing some of those bakelite blocks you will find that they are easy to do .
Glad Gary was able to help you .
Sincerely Richard
#14

Good morning tfonzart,
Sent you the tutorial just now. Good morning Richard as well.  Rich and I have been good friends for years in the radio groups.

 The tutorial was 11MB and would not upload here, so email was the only way. Unless I go back and create a new post with individual photos and text.
I can post a pic of what the best case scenario  would look like, the tar inserts holding their shape, and come out as one piece.
We can see the fine wires that went to the individual caps and were soldered to the outside lugs. Most of the time they are right there and easy to use a box cutter blade to cut them.
Use only enough heat to break the bond between the tar and Bakelite. It should push right out. It does not need to 'melt out'.
  
  If you have any questions please let me know.
Take care and have a great day!!
Gary Maker (rabbitt)  
   
#15

Great PDF Gary. Thanks so much!




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