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 Post subject: Cary Audio CAD211FE and AES Six Pac Amplifier Repairs
PostPosted: Sep Mon 03, 2018 5:54 pm 
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Location: Raleigh, NC
I'm not sure if these amplifiers qualify as antique but they look to be made in the same fashion as old radios.

I traded labor last year for two huge amplifiers. They weigh 95 pounds a piece!

I was given a great deal but they are in need of plenty of work.

I removed the bottom covers and it looks like these amplifiers were sitting under a cocktail stand at a New Years Eve party in Times Square!

The amplifiers seemed to play fine before the system was dismantled, but from above, I noticed obvious damage to the 845 tubes and sockets.

I also noticed that one of the front panel milliamp meters was stuck. The needle would not go to zero when the amp was shut off.


Last edited by Smoky on Nov Tue 06, 2018 10:27 pm, edited 1 time in total.

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 Post subject: Re: Cary Audio CAD211FE Mono Amplifier Repairs
PostPosted: Sep Mon 03, 2018 7:34 pm 
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The panel meter was stuck due to moisture and it had green tarnish on the inside of its plastic case.

The 6SL7 tube socket is directly above the meter so if anything spills on the amp the liquid falls right on top of the meter housing.

Is there a stiff material that I can create a deflector out of for above the new meter? I imagine it will need to be able to handle the heat of the socket and not transfer it to the plastic.

As for a new meter, Cary Audio sells a new Hoyt meter for $325.

I searched Ebay and found four brand new Remco milliamp meters for $15 each. The guy who sold them to me said they were made for airplanes. That's good enough for me :)

I tested one and it works and fits perfectly. I sort of like the way it doesn't have a "dummy" mark for the suggested bias setting.


Attachments:
Meter3.jpg
Meter3.jpg [ 139.84 KiB | Viewed 1839 times ]


Last edited by Smoky on Feb Mon 11, 2019 3:53 am, edited 2 times in total.
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 Post subject: Re: Cary Audio CAD211FE Mono Amplifier Repairs
PostPosted: Sep Mon 03, 2018 7:57 pm 
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I don't know why it doesn't show it, but these sockets are absolutely cruddy!

Green tarnish, rust, and goo. Scrubbing with cleaners don't budge it.

The large 845 sockets are bent from above and look cheap. They don't look American made either.

The smaller 4 pin socket is missing one of the contact pads that grip the vacuum tube pins.

I am going to replace all of the sockets in both amplifiers.


Attachments:
Sockets1.jpg
Sockets1.jpg [ 124.3 KiB | Viewed 1830 times ]
PinContact1.jpg
PinContact1.jpg [ 157.18 KiB | Viewed 1811 times ]


Last edited by Smoky on Sep Tue 04, 2018 12:49 am, edited 3 times in total.
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 Post subject: Re: Cary Audio CAD211FE Mono Amplifier Repairs
PostPosted: Sep Mon 03, 2018 8:22 pm 
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Ebay is such great resource for finding old stuff.

I found four E.F. Johnson American made sockets that look to be exact replacements. Even the prongs that make contact with the pins on the 845 tubes look different and are of better quality.

The smaller four pin sockets came from Greece of all places but are made in the USA by Aer-O-Com! $40 for 4.

I'm also going to use old-stock octal sockets made in Russia. They seem to be of very good quality plus you can index the alignment pin of the tube to be perpendicular to the center line of the mounting studs on the Cary chassis. The sockets were shipped from Slovakia.

I think all of the "new" sockets that I'm going to use to rebuild these amps were made before I was born. That's over 50 years ago folks :)


Attachments:
Sockets2.jpg
Sockets2.jpg [ 115.62 KiB | Viewed 1830 times ]
Sockets3.jpg
Sockets3.jpg [ 139.44 KiB | Viewed 1830 times ]
Russian3.jpg
Russian3.jpg [ 100.35 KiB | Viewed 1787 times ]


Last edited by Smoky on Dec Wed 05, 2018 1:42 am, edited 3 times in total.
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 Post subject: Re: Cary Audio CAD211FE Mono Amplifier Repairs
PostPosted: Sep Mon 03, 2018 11:39 pm 
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The other things that I found that don't work were the two small lamps that light small blue globes for the milliamp meters.

It looks like the small bulbs were replaced at least once before because I see heat-shrink tubing half way the length of the supply leads where it looks to have been spliced.

I had extra 8v 35ma wired lamps but they're too big and touch the blue globe when snapped in.

I was wondering if these could be swapped out using LED's?

I turned both amplifiers on for 10 minutes and at the lugs where the wires are soldered I measured 14.5 to 14.8 volts DC.

The LED's would need to fit inside the socket and globe so I imagine the smallest size LED would be needed.

The resistor (unknown) would need to be added further down the wire.


Attachments:
Cal2.jpg
Cal2.jpg [ 136.74 KiB | Viewed 1814 times ]
Blue1.jpg
Blue1.jpg [ 37.08 KiB | Viewed 1814 times ]
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 Post subject: Re: Cary Audio CAD211FE Mono Amplifier Repairs
PostPosted: Sep Tue 04, 2018 1:17 am 
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I have two operating tables.

I'll do two or three steps on one amplifier, compare, then amputate and graft the other :)

Some of the terminal strips attached to the tube sockets were struck with some corrosion where they are fastened under the nut and washer. I found some NOS Sprague terminal strips to replace those affected.


Attachments:
Gurney1-1.jpg
Gurney1-1.jpg [ 148.71 KiB | Viewed 1810 times ]
Sprague1.jpg
Sprague1.jpg [ 132.33 KiB | Viewed 1761 times ]
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 Post subject: Re: Cary Audio CAD211FE Mono Amplifier Repairs
PostPosted: Oct Mon 29, 2018 12:15 am 
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Couldn't pick a better weekend to start fixing these amps, a cold and wet one :)

Taking things apart inside these beasts is slow since Cary Audio practically tied wires and components into knots before soldering them!

All of the resistors and capacitors I removed were straightened and sleeved with new PVC.

I was able to get two of the 211 sockets and one of the 4-pin (224) sockets done today. Two of the terminal strips attached to the 4-pin socket were replaced too.

When the amps were assembled at the factory, Cary used the same nut with a star washer to space the 4-pin socket below the top of the amp. I visited Home Depot and picked up some aluminum spacers for a better look.

The 6CA7 and the 6LS7 sockets are in. I'm also testing clearances of wires and terminals by inserting a tube to replicate the wiggling. Tackling the desoldering is extremely tedius since I need to reuse most everything. I have a great deal of respect for those who do this sort of work on a daily basis.

One thing I do notice is the high quality electronic components that are used by Cary Audio to build these things!

On the last 4-pin socket to be replaced in this amp, I found the terminal tie strip cracked in half. Cary Audio uses a back-up wire to each ground terminal throughout the amp so this damage went unnoticed. These amplifiers will be better than new when they're done. The old-stock Sprague tie strips I bought to replace these are super-beefy in comparison. It's also nice that Cary Audio is just a few blocks from my house in case I need small parts too :)


Attachments:
Resist1.jpg
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File comment: Nothing beats Made in the USA!
Socket1.jpg
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Spacer1.jpg
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File comment: New Russian octal sockets installed.
6CA7.jpg
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File comment: Old tie strip cracked in half on old socket.
Crack1.jpg
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File comment: New 300B 4-pin tube sockets and tie strips installed.
Socket4.jpg
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File comment: All new sockets installed!
Sockets4.jpg
Sockets4.jpg [ 178.73 KiB | Viewed 1708 times ]


Last edited by Smoky on Nov Fri 16, 2018 7:44 am, edited 8 times in total.
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 Post subject: Re: Cary Audio CAD211FE Mono Amplifier Repairs
PostPosted: Nov Sun 04, 2018 2:51 am 
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All of the sockets on both amplifiers are finished :)

As I was working my way through both amps, I noticed that many of the mounts used to secure capacitors were just dangling around. The white foam tape used to stick them to the chassis had failed. I went to the local autobody store and picked up a roll of 3M attachment tape used for body side mouldings. This stuff never lets go of what it makes contact with.

I'm ready to install the new front panel meters. Here's where I'm trying my best to align the pointer to zero it out because how do you get to it after it's installed? So I take some measurements and would you believe it? The pointer adjustment screw on the meter housing is directly, and I mean dead-center, of the 6SL7 socket above! Just remove the front tube and stick a plastic screw driver through the hole down over the meter!

As for the idea to use LED's to illuminate the meter instead of factory installed incandescent bulbs, I was told to NOT use LED's. They may induce hum.

**The Testing Begins**

With the new panel meters installed, I cleaned up the interior of the amplifiers and inspected the wiring one last time.

I began to test each amp one at a time using the same set of tubes to limit the variables.

I connected a 4 ohm Bose speaker to listen for noise and I used it on both amps too.

When I turned on the amplifier, the filaments of all of the front four tubes glowed nicely. When the standby switch is switched to power, the 845 tubes and the bias meter were activated. Everything functioned properly :)

I tested the accuracy of the milliamp meters between amplifiers the only way I could think of. After I adjusted the panel meters to 100 milliamps with the first set of 845 tubes, I tested both amplifiers again using a second pair of 845 tubes. The change in the readings of the milliamp meters was the same in both amps.


Attachments:
Amp211.jpg
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Attach1.jpg
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MeterCal.jpg
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Meter4.jpg
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DeadCenter.jpg
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Bose1.jpg
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Front1.jpg
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Tubes1.jpg
Tubes1.jpg [ 195.28 KiB | Viewed 1621 times ]


Last edited by Smoky on Nov Mon 05, 2018 7:00 am, edited 16 times in total.
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 Post subject: Re: Cary Audio CAD211FE Mono Amplifier Repairs
PostPosted: Nov Sun 04, 2018 3:00 am 
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Great project, thanks for posting progress.

When you get a chance, how about a full view of those beauties.

Tim


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 Post subject: Re: Cary Audio CAD211FE Mono Amplifier Repairs
PostPosted: Nov Sun 04, 2018 3:25 am 
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Thank you Tim!

This has been so much fun.

I'll keep posting pictures until it's finished.

John


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 Post subject: Re: Cary Audio CAD211FE Mono Amplifier Repairs
PostPosted: Nov Mon 05, 2018 10:11 pm 
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I plugged in my Tektronix TDS420 to do some tests.

Here's what I did. I have two pairs of used 845 vacuum tubes. I do not know if they're matched or not. They were pulled from boxes in storage.

I connected a 4 ohm Bose speaker to the amplifier's speaker outputs. I connected the oscilloscope's probe to the (+) speaker terminal and its ground wire to the (-) speaker terminal. The upper waveform is the probe and the lower waveform is the FFT math function.

The first picture, Test1, is the first pair of 845 tubes on amp A and picture, Test2, is the second pair of 845 tubes on amp A. You can see the difference in the noise level between the two pairs of tubes.

Pictures Test3 and Test4 is the same except the test is being done on amp B.

What I noticed is how close each amplifier reacted to each pair of tubes. The results are almost identical.

My question is, is the noise level for the first pair of tubes acceptable (~1millivolt)? If I moved the probe's cord during the test, I could see the reading drop to 650 microvolts. For each test, I put my ear next to the speaker. I could hear the difference between the pairs of tubes.


Attachments:
Test1.jpg
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Test2.jpg
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Test3.jpg
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Test4.jpg
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Bench1.jpg
Bench1.jpg [ 202.97 KiB | Viewed 1595 times ]


Last edited by Smoky on Nov Fri 16, 2018 7:31 am, edited 2 times in total.
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 Post subject: Re: Cary Audio CAD211FE Mono Amplifier Repairs
PostPosted: Nov Tue 06, 2018 1:02 am 
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Holy Moly, from the two pairs of 845 tubes, I took one from each and tested that pair. The noise level didn't exceed 860 microvolts.

I think a fresh set of matched tubes are going to make a great difference!

I feel these amplifiers are performing quite well ...so far :)


Attachments:
Test5.jpg
Test5.jpg [ 161.18 KiB | Viewed 1590 times ]
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 Post subject: Re: Cary Audio CAD211FE and AES Six Pac Amplifier Repairs
PostPosted: Nov Tue 06, 2018 10:46 pm 
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Since I'm going to repair and upgrade several tube amplifiers, I'm going to keep them all on one thread.

These Six Pac amplifiers are in excellent condition aesthetically, but I watched two YouTube videos where Paul of "Mr Carlson's Lab" did a full-blown restoration on his pair, and hey, why not do the same to mine :)

Paul did an incredible job clearing the signal of unwanted noise.

I'm on a journey to reach that same goal.

Since the CAD211 amplifiers are waiting for more test equipment and parts, I'm going to open up the Six Pac's too.

The test equipment that I still need is a signal generator and a capacitor tester.

The Cary SLP98P preamplifier is also going to be tended to. It's going to have its faceplate and knobs switched from black to silver. I'm also going to upgrade its capacitors.


Attachments:
CaryAES.jpg
CaryAES.jpg [ 196.05 KiB | Viewed 1549 times ]
Preamp1.jpg
Preamp1.jpg [ 150.9 KiB | Viewed 1545 times ]
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 Post subject: Re: Cary Audio CAD211FE and AES Six Pac Amplifier Repairs
PostPosted: Nov Wed 07, 2018 4:35 am 
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I opened the Six Pac amplifiers to see what looked similar to the amplifiers Paul of "Mr Carlson's Lab" found in his pair of amps.

Obvious differences were the Jensen and KimberKap capacitors that stood out by their color.

The big deal for me was to see if my amplifier was also without capacitance on the line entering into the high voltage reactor. It is without. Paul also recommends in his video to have the reactor moved to another location and placed on standoffs.

I will follow Paul's lead in curing the ringing and buzz associated with the reactor. When he relocated the reactor to the side of the chassis, that step alone dropped the noise floor by 4 millivolts! Adding the capacitors eliminated the ringing and buzz.

I will also replace the Nichicon capacitors with new long-life radials too.

The date codes I found printed on the Nichicon capacitors are 0228 and 0410. I'm guessing that these amplifiers were built as early as 2004.

I can not put the amplifiers on the oscilloscope because, unlike the CAD221Fe's, the Six Pac amps don't have a milliamp meter. And neither do I :)

So back to Ebay I go!


Attachments:
File comment: Front half
SixPac1.jpg
SixPac1.jpg [ 168.33 KiB | Viewed 1531 times ]
File comment: Back half
SixPac2.jpg
SixPac2.jpg [ 186.65 KiB | Viewed 1531 times ]


Last edited by Smoky on Dec Wed 05, 2018 1:53 am, edited 4 times in total.
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 Post subject: Re: Cary Audio CAD211FE and AES Six Pac Amplifier Repairs
PostPosted: Nov Sun 11, 2018 6:41 am 
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So I'm searching Ebay for a milliamp meter for the tube amplifiers.

I come across this one with terminals coming out of the top of it. I think, Wow! I like that :)

It's a huge Triplett 0-300ma meter in a Daka-Ware bakelite project box. Only $13.

It's in beautiful condition too and as accurate as a Swiss watch :)

All I need now is a plaid cloth cable to connect the two!

**Update**

While replacing the the sockets in the CAD211 amplifiers, I noticed that the hook-up wire used in the amp was unusual.

I stripped a piece of it and noticed it is constructed using 7 strands of copper of different gauges.

I come to find out it TCSS wire made by Kimber. I got on the horn to Handmade Electronics and ordered some up. I was told that it was cryogenically treated. I replied to them not to worry because I am going to solder it and it won't feel so cold anymore :)

I found some cool 18g retro cloth cord at Snake Head Vintage for the milliamp meter too!


Attachments:
Triplett2.jpg
Triplett2.jpg [ 190.51 KiB | Viewed 1460 times ]
Triplett1.jpg
Triplett1.jpg [ 148.08 KiB | Viewed 1460 times ]
TCSS.jpg
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File comment: Stylin' & Profilin'
Triplett3.jpg
Triplett3.jpg [ 133.93 KiB | Viewed 1260 times ]


Last edited by Smoky on Nov Mon 19, 2018 4:58 am, edited 3 times in total.
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 Post subject: Re: Cary Audio CAD211FE and AES Six Pac Amplifier Repairs
PostPosted: Nov Thu 15, 2018 11:31 pm 
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OMG!!!

Over the weekend, I swapped out all of the Nichicon VX(M) capacitors on one of the CAD211 amplifiers. I purchased new capacitors based on all of the spec sheets I could read and axial vs radial types.

Since the original Nichicons were under the category of "general purpose" 2,000 hour 85° C capacitors, I didn't go too crazy. The capacitors were located in the power supply/transformer areas.

I chose extremely high life span (12-20,000 hour) and 105° C radial capacitors by Rubycon and Nichicon. Their ripple current capacities at 120hz are through the roof! On all of the newly installed capacitors I attached them using Kimber wire leads to ease future replacement.

So I power up the amplifier and connect my TDS420 oscilloscope and the Bose speaker.

My heart immediately sinks to my stomach! 27 millivolts of noise read on the scope!!!

Ok, I remember reading about newly-installed capacitors and how they need to "settle-in."

All of a sudden I watch the waveform gradually change. 23 millivolts, 19 millivolts, 14 millivolts, 11, 7, 3...

After a couple more minutes, the scope is averaging 580 MICROVOLTS!!!

That's 300 microvolts less in the noise floor than before the capacitor swap, which was ~860 microvolts!

There are now only the Cardas and Solen capacitors up front and four Lelon 10,000uf 16v capacitors attached to the bridge rectifiers, which I think are called "smoothing" capacitors.


Attachments:
File comment: Old capacitors by Nichicon.
Nichicon1.jpg
Nichicon1.jpg [ 128.48 KiB | Viewed 1371 times ]
Rubycon1.jpg
Rubycon1.jpg [ 81.8 KiB | Viewed 1370 times ]
File comment: Three radial Rubycon 47uf 450v 105°C 20,000 hr in series with Kimber wire and mount.
Rubycon450x3.jpg
Rubycon450x3.jpg [ 183.25 KiB | Viewed 1353 times ]


Last edited by Smoky on Jan Tue 01, 2019 4:06 am, edited 9 times in total.
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 Post subject: Re: Cary Audio CAD211FE and AES Six Pac Amplifier Repairs
PostPosted: Nov Fri 16, 2018 1:54 am 
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If you are an owner of a CAD211FE, here is something that you need to be aware of.

On the back of the amplifier there is a chrome toggle switch that controls the RCA jack and the XLR jack.

During the times that my oscilloscope has been attached to the speaker outputs for noise floor tests, if my fingers just happen to touch the metal on that toggle switch, it was reflected on the waveform of my scope by adding over 5 millivolts of noise!

Somehow, the metal on that toggle switch is directly coupled to the incoming signal being fed to your amplifier. Meaning, the noise it picks up is being played along with your music.

It's like a small antenna :)

I'm going to find a replacement switch with a plastic or non-metallic toggle.


Attachments:
Switch1.jpg
Switch1.jpg [ 112.28 KiB | Viewed 1358 times ]
Switch2.jpg
Switch2.jpg [ 161.1 KiB | Viewed 1358 times ]
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 Post subject: Re: Cary Audio CAD211FE and AES Six Pac Amplifier Repairs
PostPosted: Nov Fri 16, 2018 7:15 am 
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One of my new testing tools arrived today! It's a Peak ESR+ meter :)

And in another box are my new Nichicon smoothing capacitors.

After having read a few articles about bridge rectifiers, I wanted to experiment by trying a capacitor with a greater amount of ripple current capacity. Currently, two Lelon TEA 10,000uf 16v capacitors are attached to each bridge rectifier in parallel. On Lelon's spec sheet, this capacitor has a ripple current capacity of 2.5 amps at 120hz. What I found interesting about Lelon's spec sheets is that not only do they supply a multiplier for ripple current at frequency but that they also provide a multiplier for ripple current at temperature. For instance, Lelon's capacitor's ripple current of 2.5 amps is at 85°C. If the equipment that the capacitors are installed in is being used in a 70°C environment, the multiplier is 1.4 of the 85°C rating.

I decided to try the Nichicon Gold Tune II capacitors. The 16v and the 25v weren't available so I bought the 35v 10,000uf version. Though larger in size physically, they will still tuck in mainly due to them being radials and not axials like the Lelons. The ripple current of the Nichicon capacitors at 85°C is 3.8 amps at 120hz. I have no idea of what the temperature inside of a CAD211FE is, but if it's 70°C or less and the multiplier for temperature holds true across brands, each capacitor will break the 5 amp threshold by a long shot.

I needed only eight capacitors but I bought ten because the price break made the total cost the same. I checked all ten with the ESR meter and eight measure identical capacitance!

...and on a side note, this restoration is a tribute and in memory of Dan Lilley of Raleigh, North Carolina.


Attachments:
ESRmeter.jpg
ESRmeter.jpg [ 157.01 KiB | Viewed 1308 times ]
GoldTuneII.jpg
GoldTuneII.jpg [ 169.64 KiB | Viewed 1306 times ]


Last edited by Smoky on Mar Fri 08, 2019 9:07 am, edited 3 times in total.
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 Post subject: Re: Cary Audio CAD211FE and AES Six Pac Amplifier Repairs
PostPosted: Nov Sun 18, 2018 2:15 am 
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Crossed another bridge!

Last week I spent some time trying to locate new lamps for the CAD211 milliamp meters. All I knew was that the dc voltage at the terminals where the wire leads were attached is between 14.3v to 14.8 volts.

It was when I typed "blue wired lamp" on the internet. I scrolled through the images. I had another "OMG" moment :)

I click on the picture and it sends me to Radio Shack's website!!!

I see what appears to be the real-deal! Sure enough, blue and red snap-in lamp assemblies!

The package reads, 12 volt 10,000 hour Lamp Assembly but with no amperage noted on the label.

Four in-stock for red, two for blue, $2 per pair!!! Free shipping!!!

I can't type my Paypal password fast enough :)

With them here with me, I set my old Kepco power supply to dead-nuts 12.0 volts. I attach one lead of the lamp to the power and the other to my Fluke 8024B. Amperage reads ~64 milliamps.

It appears that these long-life lamps died early due to heat along with a little too much voltage.

I went to a website that has a dropping resistor calculator. To drop from 14.5v to 12v, I would need a 40 ohm resistor. Digi-Key has 1%, 1watt, wirewound Vishay Dale resistors in stock. ALSR0140R00FE12.

Who knows? I may try the red globes for the Holidays to spread a little Christmas cheer :)

**Update**

The high accuracy, 1%, 40 ohm resistors came in!

With the resistors in hand, this time I set the Kepco power supply to match the amplifier's voltage to the meter lamps, 14.5 vdc.

In-line with the lamp, I put the resistor and the multimeter to read the milliamps. It displays 62.9 milliamps at 14.5 vdc!

The online dropping resistor calculator worked!

These lamps should live a much longer and cooler life :)


Attachments:
RadioShack1.jpg
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File comment: Kepco power supply set to 12vdc.
LampAmp1.jpg
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Resistor40.jpg
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File comment: Kepco power supply set to 14.5vdc.
LampFix1.jpg
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File comment: "D-U-N" done :)
DUN.jpg
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Gett'nThere.jpg
Gett'nThere.jpg [ 194.58 KiB | Viewed 1083 times ]


Last edited by Smoky on Nov Sun 25, 2018 9:28 pm, edited 11 times in total.
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 Post subject: Re: Cary Audio CAD211FE and AES Six Pac Amplifier Repairs
PostPosted: Nov Mon 19, 2018 5:11 am 
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I'm jumping over to the Six Pac amps for a second since I now own a milliamp meter :)

I turned on one amp and plugged in the milliamp meter and also the Bose speaker. I let the amp warm up until the room rose 5° :) I then set its bias to 230 milliamps.

Sure enough, this amp suffers from the same buzz and hum Paul Carlson found emitting from his Six Pac amplifiers.

Adding the .47uf capacitors to the relocated high voltage reactor and the installation of new capacitors are in the future for both Six Pacs.

Tomorrow I will hook up the amp to the TDS420 to get a baseline for the noise floor. It's bound to be high because the noise I hear from the Bose speaker is very noticeable.

**First oscilloscope test for Six Pac**

Every day I can't wait to get home from work so I can work on these amps :)

The reading on the oscilloscope shows what I can hear out of the Bose speaker, close to 8 millivolts!!

These babies are going to get a thorough renovation. No wonder I found these amps stored in the back of a closet!

To maintain the most accurate tests, the same combination of tubes will be used in both amplifiers and placed in the same positions.


Attachments:
SixPac3-1.jpg
SixPac3-1.jpg [ 132.95 KiB | Viewed 1259 times ]
File comment: The first test on Six Pac for baseline noise.
SixPacTest1.jpg
SixPacTest1.jpg [ 134.67 KiB | Viewed 1223 times ]


Last edited by Smoky on Mar Fri 08, 2019 9:06 am, edited 3 times in total.
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