8/27/2013

Bose Wave Radio Generation I Version 2

I recently acquired a 1st generation BWR from a goodwill for $8. It would only output a buzzing noise but everything else worked.
 
I did my research and found out the following in regards to the first 3 versions of this radio:
They are ALWAYS on. The on off button is just a mute button.
The capacitors in them are mostly low quality.
IF you get an early BWR and it works you WILL be recapping it soon.
I would recap it now as the TDA7374 can be blown out when the caps go bad.
There are more than 40 ecaps in them.
The board in my model (version 2) is prone to solder pads breaking and coming off.
look for a film on the board around the capacitors if it is there clean the board.
Replace ALL small capacitor in the unit, even on the display. You can usually skip the 10000uf main filter cap.
If your tda7374 is bad it can be replace with a tda7375. Ebay has them for $6 to $12

My impression of the sound from this radio, since I had never heard one before.
It is very good. I would compare it to a ported 2 way bookshelf speaker with a 5 or 6 inch woofer and a 2 inch tweeter.
Contrary to what I have been reading it is stereo. Confirmed with some songs with discrete channels.
The left speaker is the mid range "woofer" (and left channel) with low frequency sound channeled through a port by the right speaker. The right speaker is mid to high range as well as right channel.
A big part of the sound is the built in equalizer, I would liken its output to the "loudness" button on an older stereo or the old smiley face on a graphic equalizer.
The TDA7374 is interesting, it is a Dual Bridge audio amplifier for car radios.

My radio has an external AM antenna which has relatively good sensitivity. Newer versions have a loopstick.

I will be keeping this one as I made several mistakes working on it that I corrected but would not in good conscience sell to someone else. I will keep an eye out for them as they sell for $125+ on ebay.

Some schematics are available here.

I have read on several forums that you can also call Bose and they will send you the schematics for your radio.

8/24/2013

Emerson 641B

Another Ebay purchase made with birthday money from my Mother-in-law. I saw one just like it in a local antique store for $40 but cosmetically in worse condition.The knobs on the one in the antique store were munged.
 Pic below taken after I removed the old filter cap.
It hummed on power up which means the electrolytic power filter caps were bad. I replaced them. 

I powered it up again and the hum was gone, but all I got was horrible static and faint KTAR 620am.
Hmm.... I then did a full recap, but the static persisted. Attempting an alignment did not improve anything. Some research makes me think that it has silver mica disease and I had to rebuild the 1st IF transformers. I replaced the power cord at this time.

Once I had the 1st IF Transformer rebuilt, I did an initial alignment and found it was still a little weak. I tested all the 6BJ6 tubes and found two were not as good as I would like. I picked up 4 NOS tubes and replaced all the ones in the radio (since the NOS ones tested better than originals). I did a final alignment, installed an audio in, and the radio works great.

8/23/2013

3 Radios from Ebay

I got these 3 radios off of ebay Monday 8-12-2013 at 6:00pm (Birthday money from Mother-in-law). With local pickup I got them for a really low price. Met the seller at a Walmart on 19th ave and bell.

Left to right.
Zenith - 2-2034
Motorola Model AT28AH
Westinghouse Century CR-510

The Westinghouse was not working and I had to replace the multisection electrolytic capacitor since it was shorted. the Power switch would not make contact (shot of deoxit), the 35w4, 50c5, and 12av6 had burned out heaters. Did an alignment, and it seems to be really sensitive. I had it fixed by 8:00pm.

The Motorola needed only slight repair. I did an alignment on it as well.

I parted out the Zenith as it was microphoning and had lots of problems. I thought it was ugly anyways.

8/20/2013

Sears Silvertone 8013

Got this radio off of ebay as well. I should have looked closer at the pics as there are cracks on top and bottom. I fixed them with epoxy and found a missing piece inside the chassis. I also had to epoxy the plastic pieces that the screw for the back panel screw in to. The plastic in this radio is very brittle.
 If I remember correctly this radio did not need a recap. I did replace the phono RCA jack with a 3.5mm Audio/MP3 input. Picture below is before that.
I could not find a schematic etc. for this radio on line but everything was on the bottom.



8/18/2013

General Electric T104A

Got this off Ebay for a nice price. Needed a minor recap, and added an Audio/MP3 input on it.
 Created a replacement sticker for the back and dyed it with coffee.
It's nothing exciting to look at but was in such nice condition I could not pass it up.