Truetone D 2026 radio recapping - Muddy bass when hot

I recapped an old Truetone D 2026. It had some bad leaky IF coupling capacitors. I cleaned off the grime, sprayed the pots and oiled the tuner. I also recapped the main filter cap too. I was quite dignified of how I used a binding post to route the funny looking dogbone resistors and mount the new filter caps. Still it is improved but It has some potential over - modulation problem though. don't exactly know what's causing that.

http://www.radiomuseum.org/r/western_au_d2026_d_2026_series_a_tru.html

Note, this is not my first recap job. My first recap job was actually an Eico Ocilliscope I aquired over Ebay for 13$ around 2003. That tube driven scope did not work either when I got it :) Now it actually shows waveforms! Still needs work as waveforms come in squashy lol. I'll save that for another vid :)

As a bonus, this is my first major video editing job :)

Category:

Science & Technology

Tags:

• old
• radio
• repair
• leaky
• capacitor
• electrolyte
• speaker
• dogbone
• resistor
• tuning
• in
• bad
• fm
• good
• am
• overmodulation
• midi
• music
• intro
• electronics
• shop
• oldies
• 98.5
• the
• peak

[blakepeary]

did you find the schematic for this radio?

[simpsonizer]

@blakepeary Nope. I looked online for one but gave up. The only site I could find any info I belive was antiqueradios (darn youtube wont allow sites)

[simpsonizer]

@basspig I fully understand what you are saying! Thanks! I wish I had a spectrum analyzer in my shop though. I do use a spectrum analyzer on my computer for audio work though through software :-)

[basspig]

@simpsonizer It's definately worth checking the resistors to find out if they are in tolerance. A lot of times with these receivers, there is a problem with 60cps power supply hum getting into the IF strip and intermodulating the audio, but in your case, it sounds like improper tube bias and possibly and IF strip that is tuned too narrow. The proper skirt should look like an "M" on a spectrum analyzer.

[simpsonizer]

@basspig Thanks! I will have to look into that! It does get distorted when it heats up to operating temperature. Do I need to check the resistors that bias the tubes for a potential drift? I used new yellow film caps BTW. Could one be bad? I am sure I also replaced the line filter cap can too.

[basspig]

@simpsonizer The correct term is ''intermodulation distortion''. Try checking the bias on the IF stages, limiter/ratio detector and first audio stage. Leaky cap would be my first guess.

[blakepeary]

how do you get the knobs off?

[blakepeary]

how did you clean the golden part of your radio?Mine has a bass problem too and i have the same radio.

[Sonovox01]

Ah ok. Thanks!

[simpsonizer]

I was unable to cure it, but I did only improve it by fine-tuning it (IF coils) and replacing the main filter cap. I belive the problem is either a weak tube or, capacitor that is out of value. (This was a restoration to get it working for now :) - Take care!