Refreshing The Fisher XP-9C Speakers Part II

After I received the non polarized electrolytics I replaced them on the crossover. I had to order extra 50uf capacitors as Parts Express did not carry 25uf caps. I put 2 - 50uf caps in series to get 25uf.
To make a good seal around the speakers I picked up some weather stripping. I wanted a good seal since this is an acoustic suspension system.
I used a hair dryer and a vacuum to pop out the pushed in "fried egg" tweeter. One will not pop out and I will have to work on it.
 I put everything together and hooked it up to my tube amps. It sound really nice.


Pioneer SX-434

Found at Goodwill last night. Pioneer SX-434 Stereo Receiver. She needed a little TLC. I installed 3 new lamps, and a new stereo indicator light. The old one was in it's correct bracket, but the previous, previous light base was also in there. I removed that and installed a new sub mini light, installed the bracket (after removing the mess of tape on it), and hot glued it in place. Cleaning the pots was a chore as I had to remove the base, and a circuit board to get to them. Then the knobs and faceplate were cleaned, and some furniture polish cleaned up the top.
  For a small 15 watt per channel stereo this one has a real wood cover. She sounds pretty decent.


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.


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