Zenith Z374 AM/FM Clock Radio

Picked this up at goodwill. It was sitting on the test table plugged in. I did not even test.

I just bought it. I took it home and initially could not find anything wrong with it.
I did notice one major issue. FM would quit working and you would have to switch from AM to FM to get it back. Then it would drop out again.

I tested all the tubes and found that the 17ew8, and 12be6 were week. The 35c5 was intermittent and probably the reason FM would drop out. replacing all fixed the problem. The only issue remaining is that the alarm function of the switch does not work. I will have to troubleshoot that later.


Eico 377 Signal Generator

Snagged this at a goodwill for an exorbitant price. It did not work, but that was to be expected.
 It will need all new capacitors, of which I have already started working on. This thing has more electrolytic caps than anything I have worked on before.
 I counted 4 discrete caps and 2 dual section capacitors for a total of 8 electrolytic caps and 3 paper caps.
I ran out of 20uf capacitors and had to order more. I also replaced 3 out of spec resistors.


Bradford WTG 61507 AM/FM Radio

Picked this up in Prescott at an antique store. It needed all non ceramic/mylar capacitors replaced. I installed a fuse and an MP3 audio in. Still needs an alignment.
It is a Japanese made radio.
I was not able to find a schematic for it.


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.


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.


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.


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.


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.


Newcomb B-100 Schematics

Seems there are 2 different versions of the Newcomb B100 radio. An early one with octal tubes and a later one with 7 pin mini's. Top radios is the newer version and the bottom is the older. Right click on each picture and select "open link in new tab" for the full size version.
This is an under chassis picture of the early model
This is an under chassis of the newer model.
Here is the schematic for the new model.
Here is the schematic for the older model.
The older model is better in my opinion. Sounds better and works better.


Sears Silvertone 5009

Here is an AM radio I picked up from ebay.
It was listed as "for parts not working". The original picture showed it was very dirty. When I got it it had a bunch of problems. It took about 2 days to track them all down. I thought it had silver migration disease in the IF filters (it did not) I recapped it, I had to go through the circuit board and re-solder EVERY component. I had to tighten up and solder the tube sockets, In the process of working on it I broke a very fine wire on the oscillator coil and had to fix that. I replaced a few resistors. I took it apart and cleaned the case with simple green. I did a full alignment, and the only thing left is to fix the melted plastic on top and replace the interlock cord.


Motorola B12WA

When I was a kid we had one of these.
It died in the late 70's. I took it apart and trashed it. I found one on ebay.


Goodwill Haul

Being recently revenueless I kept busy fixing old radios and going to thrift stores and estate sales. This is a partial list of my haul for the last 12 months 7-2012 to 7-2013:

Magnavox 20mf500t/17 20" LCD TV
Shure 520DX
Line 6 Spider III amp
2 geiger counters
2 minimus 7's
2 veneered minimus 7's
WinTV-hvr 1600
Pioneer SX-3600
orphaned Mini Advent
wireless shipping scale
Technics SA-5460
supro S6606
Center Channel Design Acoustics PS-CV
Sansui 200
Optonica SA-5407
Proton 740 tape deck
Hewlett Packard 120b tube oscilloscope
Yamaha Natural sound GE-30 Equalizer
1 Optimus unknown speaker
1 Denon TU-450
2 Garrard GSS100 speakers
1 realistic mini amp
realistic mini tuner
Technics SA-GX130
Technics RS-T330R Tape deck
optimus pro-x88av
Garmin Etrex Legend
AC hookup wire
Technics SH-8055 12 channel GEQ
Technics SU-V57 integrated amp
Technics ST-S77 tuner
Technics RS-B17W tape deck
several Canon T-50 cameras
Many SLR Cameras and lenses
Yaesu FT-23R
Kenwood KT-42B
Fender Frontman 15G
Marantz SD155 Tape Deck
Optimus SA-155 "amp"
NAD Monitor Series Power Amplifier 2100 Power Envelope
Luxman Tuner Preamp TP-117 with BOTH remotes
Fisher DS-810 speakers
General Signal PC-150 line conditioner/isolation transformer
Ross Electronics Co. 2101, 8 band radio
craftsman 1/4" socket set
Technics SA-301
Yamaha A-32
Audiosource AMP One/A
Triad Bronze Powersub
Pioneer PL-115d
Kenwood KA-127
Fisher 215
Coral BX-200 speakers
Sansui 7070
Digital I.C. Color Generator
Polaris MT5500 marine radio
Sporty's E6B Flight computer
Technics ST-G5
GE el cheapo tube radio

Most Items were sold.


Lloyd's TM-75 Tube Radio Schematic

Lloyd's TM-75 Tube Radio Schematic.

 Uploaded these for anyone else who has one and needs the schematic and tube layout.
Click on each image for a larger version.


Refurbishing a General Electric C403D Tube Radio Part III

Radio is done for now. Just a few things left to do. Which may take a while.


Refurbishing a General Electric C403D Tube Radio Part II

Work is progressing on the little radio. I have the grill on the bottom. 
The speaker and speaker cloth are installed.
I located a speaker grill at Ace hardware. It is a brass plated shower drain guard. It was a huge pain to mount. there were 4 small tabs on the back to hammer down, I had to solder brass screws to the back of the "grill" which involved scratching up the surface, using acid flux and plumbing solder since rosin core would not do it. I had to modify the speaker to match the screw locations. There is the possibility that it could pop off at anytime since I do not have much faith in it being properly soldered (we will see). although it is not magnetic it seems to not be solid brass. When I scratched up the back I uncovered a nickel? colored metal.
I have attached a home made and artificially aged (with coffee) label on the back plate.

SO! what's left to do?

The transformer.
Better knob and dial.
Dial markings (dependent on dial).
Finish the back

all the above may go slow but the transformer and back will probably be done late this week or early next. Knobs would probably take sometime.


Refurbishing a General Electric C403D Tube Radio Part I

So a while back I purchased from ebay a radio similar to this:
 for parts not working.

Well I got it working but the clock would not keep time, the plastic case was ugly, and I do not like clock radios anyways.

I pulled the guts and gave it a newer better speaker.
 I decided to put it in a new cabinet. However it is 108 here and I had no interest in trying to build a cabinet in the heat. I went to Micheal's and picked up a small non square box to put it in for $5.00.
I then removed the lid and hinges, and glued in some supports for the components and for the back.
I drilled holes in it for the tuning knob and volume.
 I temporarily mounted the board in the radio sideways like it was in the original. I will be drilling 1 or more holes in the bottom of the cabinet later to get some air flowing over the tubes.
 I made a cutout of the speaker so that I could place it correctly. The tuning dial and volume knob are from the old radio and will probably not be going on the new cabinet. I found that I needed to move the speaker over about 3/8" from my initial placement. The speaker hole will be cut out and some cloth I picked up will go over the speaker, then I will make a decorative flange to go over the speaker and cover up the speaker hole.
 I had purchased some large beads for the feet and attached them.
I went looking for a prefabbed cutout for the speaker and could not find anything, both at craft stores and on line. I will have to keep looking as I do not have the proper tools to make what I want. I did cut out a hole in the bottom and found a small chrome fan grill to keep probing fingers out.
I also gave the wood I nice stain. However that uncovered a flaw on the bottom of the craft box. It has scratches at right angle to the grain. I had sanded the face (with the grain) but did not see it till it was stained. Oh well it gives it character. 

I have the following completed. I have figured out where to wire the pilot light. Installed the mp3 input on the board, and put on a thin coat of spray varnish. Now she needs to dry overnight. When I put the feet on this time it sits perfectly without rocking. 


Fixing a Consus Eagle USB drive

I have had a couple of these Eagle/Consus External hard drives for a while now and over the years they have given me fits. After a few months of use they start to have problems.
Usually the problem is caused by the the cheap AC adapters failing due to bad capacitors. Today I checked on my servers backups and found they have not been backing up in weeks. NICE! I cracked open the AC adapter and checked the caps and they are all fine... hmmm. I took the drive apart and everything looked ok, but I pulled one of the caps and tested it with my Atlas ESR+ and it showed out of tolerance and rather high internal resistance of 8ohms. So I pulled all the 100uf 16v caps and replaced them. They were all out of spec and had internal resistances as high as 17ohms.

Before finalizing the work I tested the drive and found that everything was working like it should.
So I finalized the repair and will do the same with the other drive I have.

Why would I bother fixing something as inexpensive as a USB enclosure? Because I hate to throw out something perfectly good if I can fix it, and I am cheap.


Newcomb B-100 Radio Restoration

I recently got 2 Newcomb B-100 Radios off of ebay. Newcomb made radios from the 40's to the 70's (I think) I cannot find much info on the company. Their radios, and other equipment were used mostly in schools. These 2 radios are slightly unusual because they are more "fancy" looking than their other models.
 The bottom one in is the older radio and the subject of this post. It was very dusty inside and surprisingly (for it's time) has a transformer.
 First thing I had to do was replace all the red beauty capacitors,
 With orange drops and 2 of the cpacitors with some Red Audiophile Capacitors. I also installed new electrolytic capacitors (not shown) but left the old multisection cap installed for looks.
  I replaced a few out of spec resistors, the power cord, moved the fuse to the back of the unit, and replaced some of the wire that connect to the antenna and speakers. I installed a 3.5mm audio in jack for playing MP3z through the radio. This radio already had a Phono circuit so it was easy to do.
 I made new labels to go over the old identification marks stained them with coffee, and covered the hole where I removed the audio out jack.
I need to recover the case and that will be fun as I do not yet have a source for the vinyl cloth to do it.

If anyone has any of the schematics or other documentation for these radios please contact.