Merrell SA-30, National Kits STA-24, Radio Shack R90LX066

After years of miserly waiting, I have acquired my first tube integrated amp from ebay, (Since the one who shall remain nameless) threw away my "The Fisher 400" Receiver while I was at college in the 80's. This one arrived Friday 10-19-2013

It was listed as an "unknown amp" I did some sleuthing and found that it was either a Radio shack, National Radio, or a Merrell kit amp.
We'll call it a Merrell SA-30 for now.

Auction pics

 Gratuitous glowing artsy tube picture.

I went to my local surplus place and found the ONLY 5u4gb they had. I paid $6 for it. I had one 6v6, and scrounged 3 more from my Newcomb B-100 Radios. I got 2 - 12at7a's from the B&K television analyst I parted out. I got 1 - 12ax7a from the same B&K and I had another marked Silvertone. At the suggestion of Tube Radio (an Antique Radios Forum member), I also replaced all the ceramic capacitors with other non ceramic caps. It is up and running and I am playing my MP3 player through it now. It needs some tweaking and maybe some matched tubes.

Things I found wrong with it. There is a large 25 watt? 200ohm resistor that (whoever wired it originally) had used WAY too thin wire. The wire was scorched on either side of the resistor. I replaced it with some larger wire. There is a fluttering/static noise when the selector is on Lo Phone/Tape. The Lo Phono connection has more gain than the other inputs. This means it works real well for my Mp3 player. I can drop the volume on the player down to 50% when hooked up there.

In the picture above of the back of the amp, there are 4 connections for each speaker. I determined that the far right connection is common, the other connections are from left to right. 4ohm, 8ohm, 16ohm. I input a sign wave in to the unit and noted that the amplitude of the wave increased as I went from right to left. The 2 RCA connections below the left speaker connectors. They are not Left and Right Tape out.

The unit supposedly does NARTB equalizing on the phono inputs (I cannot tell).

 After about 2 hours listening the Power transformer gets to be about 140°f.

I need to:
get matched tubes for it, though it plays pretty good with the hodge podge that I have in it.
make a cage/cover for it, it had one at some point and there are screw holes for one.
Make a wood base for it.
Properly label everything on the back and remove all the marking pen marks on it.

The filament voltage for the 5U4 on this this amp was over 7 volts A/C, it should be 5. I did some research and calculations that to drop 7.16 volts to 5 volts at 3 amps would take about .76 ohms 6.5 watts. I knew from past experience that it would probably not be that exact a resistor. Most calculators I found said it would take a 1 ohm 6.5 watt resistor.

I picked up 2 - 1 ohm 10 watt resistors. I found that 1 - 1 ohm resistor dropped the voltage down to about 3.5 volts. I tested the 2 resistors in parallel for .5 ohms. That brought the voltage down to 5.07 volts They do get pretty hot.

For now they are mounted sub chassis on a standoff in free air.

For anyone that is interested here is the Schematic.

Right click and open in a new tab or window. Then save the jpg. The notations on the drawing are not mine. The Filter Capacitors are not marked on the schematic and I do not know the correct values. However my amp had 40uf 350v and 20uf 350v multi section caps installed. I would replace them on both channels with 40uf 450v electrolytic caps. There is also a 200 ohm 25watt resistor coming off of the 5u4 pin 8, and before the first filter cap. I am thinking that someone put that in there to limit the voltage because without it the screen grid voltages on the 6V6 tubes is 32 volts to high.

Here are the original catalog ads for the amp.

Here is the schematic after I changed it to match my amp and making the mods that improve bass.

Refreshing The Fisher XP-9C Speakers Part I

Picked up these 2 speakers from the curb just a couple of days before the city came through.

 

On this one, someone tried to fix the cracks in the surrounds with RTV.

 The backs of the speakers.

 To get the speakers out, we tipped it over face down on the table, and smacked the Cabinet. The speaker dropped out.

 The Second speaker had to be pried out as it was glued in place. Both speakers had their sides cut to fit in the cabinets, not sure if this is factory or someone had worked on them previously and this was the only way to get them out Since the edge of the speakers would have been under the moldings.

On this speaker I removed the old surround, as suggested by the instructions from the Surround manufacturer. I found that putting Rubbing Alcohol on the old surround stained the speaker. I carefully scraped and cut out the old surround.

 On this one I ignored the instructions and did it dry. This one turned out better. I had to use razor blades and a chisel to get the remainder of the old glue off.

 In order to get the speakers properly centered while glueing them in place I elected to hook up a Signal generator set to about 400hz at medium low volume. This kept the coil moving and centered, and helped to center the surrounds. 

Here are both Speakers with the new surrounds.

 I installed them upside down like the previous ones were, as installing them the more common way would result in the surrounds rubbing against the speaker grill.

I tested the crossover and other speakers with my signal generator. It appears that the "fried egg" tweeters still work and that the crossover is still working. I will be replacing the capacitors on them anyways as they are possibly 50 years old. I have ordered the capacitors.

Removing stuck batteries from a 2 AA Maglite

I had recently replaced the batteries in one of my Maglite's (about a year ago), well as usual the batteries swelled up and started to leak, of course due to the crappy design of these flashlights it is near impossible to remove the batteries in this situation.

I tried dropping the flashlight open side down on to a throw rug on tile. While it did move the batteries down to the end of the battery It bent the very soft aluminum. I then tried to pry the batteries out but that just bent the flashlight the other way. 

I did some googleing and did not find much information on getting the batteries out. I did find that Maglite's attitude is "too bad for you". But I did manage to get the batteries out. Here is how:

First remove the lens assembly.

 Remove the light bulb.

 Remove the plastic part labeled "DO NOT REMOVE". It just pulls right off.

 using a thin screw driver placed in one or both of the holes you see above. Push down or if needed lightly hammer the batteries out. DO NOT hammer directly on the plastic switch. The switch assembly will push all the way through the tube. Once you get the batteries out (if you get them out). You will need to clean out the tube. Use a small file, a hone, brass bottle brush, or whatever you can find that will work. Rinse out the tube and thoroughly dry it. Check that the silver tab is clean, then push the switch assembly back in place as you see it above. Replace the part marked "DO NOT REMOVE". Install the bulb and clean it off with alcohol. Reassemble the rest of the flashlight with new batteries.

 VOILA!

Blonder Tongue FM only R-20

Got this off of the shopgoodwill auction site. It is FM only and the design is like a Granco 620U I have, but the speaker is WAY smaller and on the back of the radio.

Here it is, as I got it, quite dirty.

 

And after I recapped it, replaced the failing Selenium Rectifier with a silicon diode, and cleaned it up.

Here is the Schematic

Heathkit V-7A VTVM

Another Goodwill find. 2 VTVM's, a heatkit tube, and a Bell and Howell transistorized.

The Bell and Howell had major problems. A blown High tolerance resistor and one of the selectors was broken, so I parted it out. The Heatkit, however is fixable, it needs new capacitors and that is all.

Nikko STA-5010

This is a Nikko STA-5010 from goodwill.

This is a tricky unit to get sound out of on the goodwill test bench. I tried getting it working in store but no luck. However I took a chance for the low price and bought it. Instead of having to just get the speakers selected right, you have to do the following to get sound out of it:
hook up your speakers
Select your speakers
set the Tape selector to Source
and then! on the back of the unit change the switch that reads "Pre & Main" to "Connect".
This is very likely the reason it was still there when I got to the store, since I saw at least 2 flippers prowling the aisles.

All Lights work.
This stereo sounds great and I am not sure why it was donated. It is clean, a little dusty inside, I used deoxit on the volume control before turning it on so I am not sure if was scratchy. Oh well mine now! I will not be doing any replacing of parts on this unless it develops a problem.

Heathkit GR-11

From Shopgoodwill.com. Needed a recap, and the 17c9 tube replaced. While cleaning it with denatured alcohol I accidentally removed the Heathkit silk screening from the front.

 Picture taken before the recap.

The unit needs an antenna but gets really good reception. Speaker is a little small. I may put it in a new cabinet later and give it a better speaker. All the plastic standoffs were broken, but I found them inside the radio and epoxied them back on.

That's some mighty fine police work, Lou

Got a call this morning at 6:15am. Unknown number. I answer and a man asks to speak with ****. I'm like "there's no **** here". He says "This number does not belong to an older woman with a walker?"

Wait what?

So somehow when the police report was made they put my number for the number that was on the note. So I gave the "detective" the correct number and we will see what happens.

Old Woman is a Thief

What is this world coming to when strange old women come to your house, fish around in your mailbox and thieve your wife's rolling crate!

Oh and before she does that she leaves a note at the base of your security door with her phone number.

 

Yesterday my wife comes home and discovers the rolling crate she had recently purchased is gone.

I searched the events on the surveillance system and found the following:

If you aren't interested in watching the whole thing:
she comes up our drive way. Looks at our stuff, rings the doorbell and snoops in the mailbox.

she then snoops some more and goes around to the side of the house.

she returns and writes a note that she places in our security door in a location we would have NEVER found.

She empties the crate folds it up and puts it in a plastic bag and takes off.

Today I got home about 6:30pm Called the police non emergency line. Burned a CD of the video. The officer showed up about 7:45 he was here about 30 minutes. He asked what I wanted to do? I wanted to press charges. He watched the video and wrote up a report and said that he did not think anything would come of it. I said "that's fine, since she may be doing this to other people I wanted something on file". I gave him the note and the cd. will they call the number in the note and pursue this? probably not.

So once again... as long as it is not particularly an expensive item that gets thieved, and you do not get personally caught, crime does pay.

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.