The Fisher TA-600 Rebuild Thread

[spaceman]

Man, I was starting to get frazzled nerves, looking at your pics compared to mine, then I realized yours & TheRed1s are earlier versions, LOL. My serial # is 57444 H, which puts it a ways later in the production run. The biggest diff I noticed is, you have 3 coupling caps per channel, and I only have 2, plus a FEW values are different, like the little Frako 'lytics & resistors. I don't have a date stamped on the back of my faceplate either, though there "might" have been a sticker there at one time.

 

[kpaxfaq]

Interesting...

Every TA-600 I've seen has been like mine, I didn't realize there were significant differences like you're describing.

This project is going to be on hold for now. I am waiting for the custom can caps from Tom Hayseed and also need to place another big AES/mouser order. I'm trying to take an inventory of several projects at once.

Kory

 

[TheRed1]

Here's some information I just realized I had relating to the early vs. late TA-600s. The schematic below is from a Nov. 1959 edition of Electronic Technician Circuit Digest. It is identical to Fisher's but has the handy tube socket pin voltage chart. (There is a PDF of Fisher's at Jonboy55's Fisher Consoles website.) The Fisher version covers serial numbers 20001-29999.

The Sams' supplement (last two images) is from 1961 and covers serial numbers 50001-59999. I don't know if Fisher made any intermediary 30000 and 40000 series TA-600s. Since Sams did not reference them then perhaps not. Anybody have one?

The later 600s made use of a number of Couplates (I believe they are also known as PECs) in place of discreet components. Fisher also replaced the 7199 driver/phase inverter tubes with 7247s. I thought the TA-600 subset of the Fisher community might be interested. (I didn't use IMG wraps since I uploaded these at maximum resolution and they're huge. I'll send Jailtime my JPEGs for the AK database.)

TA-600 SCHEMATIC - AMP SECTION
http://i205.photobucket.com/albums/bb275/irwinbay/TA-600-A.jpg

TA-600 SCHEMATIC - TUNER SECTION
http://i205.photobucket.com/albums/bb275/irwinbay/TA-600-B.jpg

TA-600 PARTS LIST 1
http://i205.photobucket.com/albums/bb275/irwinbay/TA-600-D.jpg

TA-600 PARTS LIST 2
http://i205.photobucket.com/albums/bb275/irwinbay/TA-600-E.jpg

TA-600 SAMS SUPPLEMENT 1961
http://i205.photobucket.com/albums/bb275/irwinbay/TA-600-F.jpg

TA-600 SAMS SUPPLEMENT 1961 SCHEMATIC
http://i205.photobucket.com/albums/bb275/irwinbay/TA-600-G.jpg

EDIT: Kpaxfaq, just noticed that your 600 is in the 30000 series. Does the schematic you're using cover that range of serial numbers?

 

[spaceman]

Whoa, that's pretty interesting, that they completely changed the driver tubes. I had no idea you guys had 7199s in yours, just figured they changed the circuit a bit along the way. I know from my S-C amps, that the 7199 is a bit rare, no idea about my 7247s. :scratch2: My 7247s are RCA-branded, but made in Japan, and since they have seams at the top, I'd guess they're "probably" Matsushitas (made on old Mullard gear). EDIT: BTW, I had a good look at the volume pot/AC switch from my old 610-STs, and I'm 90% sure it's the same, just a tiny bit shorter shaft. One is in great condition, and I'll swap it into the 600 eventually, but the other one's kinda rough.

 

[TheRed1]

Note that the early 600s don't have a center channel output. I wonder how many changes it took to trigger a new model number in a Fisher.

 

[kpaxfaq]

Update:

Just got an email alert that my custom can caps from Tom Hayseed have been shipped! Not bad, paid on March 1st and they've been shipped on the 15th.

Can't wait to get them installed and see if the 5AR4 arching disappears :thmbsp:

Kory

 

[2SB56]

Maybe I'm a little late to the party, but uuF is indeed the really old school way of notating picofarads. Since a microfarad is 0.0000001 Farad, then a micro-microfarad is 0.000001 microfarad, or 0.000000000001 Farad, which is one picofarad.
1 = 1 Farad
.001 = 1 millifarad (a.k.a 1000 microfarads)
.000001 = 1 microfarad
.000000001 = 1 nanofarad (a.k.a. 0.001 microfarads)
.000000000001 = 1 picofarad (a.k.a 1 micro-microfarad)

 

[kpaxfaq]

Maybe I'm a little late to the party, but uuF is indeed the really old school way of notating picofarads. Since a microfarad is 0.0000001 Farad, then a micro-microfarad is 0.000001 microfarad, or 0.000000000001 Farad, which is one picofarad.
1 = 1 Farad
.001 = 1 millifarad (a.k.a 1000 microfarads)
.000001 = 1 microfarad
.000000001 = 1 nanofarad (a.k.a. 0.001 microfarads)
.000000000001 = 1 picofarad (a.k.a 1 micro-microfarad)

Yeah I later noticed right on the parts list it said uuf = picofarads

Damn small print

 

[kpaxfaq]

Just got an email from my girlfriend reporting the can caps from Hayseed arrived in the mail today!

Payment sent 3/2/11, Caps are now finished at my doorstep on 3/17/11. Quite a quick turn around time! One can was $27.25 and the other $27.95 with $7.95 to ship. Honestly can't see why I'd order another can from a retailer again for $30+ when I can contact Tom and have a can made to my liking for this price...

Also in the same day a Fisher KM-60 tuner in nice shape arrived as well! Sounds like I have my hands full for a fun evening tonight.

The KM-60 was allegedly assembled/owned by a Dentist who then installed it with a Fisher KX-200 integrated amp he also assembled in the wall of his home. The original owner recently went into assisted living and sold his home. The new owners removed the units during remodeling and sold them which is how I came across it. I always enjoy learning the orgins of equipment if I can :yes:

Stay tuned :thmbsp:

 

[kpaxfaq]

Here's a pic of the new custom can caps from Hayseed Hamfest :thmbsp:

Now it's time to remove the old cans. Here's a before pic. I carefully noted which color wires and resistors went to each leg of the can.

Here's a pic of the new cans installed in place! (Now before anyone points out an error, I will be explaining it below because it baffled me for about 30 minutes )

So...I plug her in with speakers connected. Everything comes up just fine. No more arching of the 5AR4!

So now I'm trying to get FM or AUX to play. Nothing, not a darn thing. I get some crackling when I measure voltages so the OT's must be fine. So I sit there monkeying with it for about 30 minutes, tried different tubes, etc. Checked for loose connections, wires....NOTHING. So I go shower do some other stuff....All of a sudden it hits me....I never installed the new 4.7K resistors on the can terminals like you notice in the original setup! So I run up, do that and IT'S ALIVE! FM/AM sound fantastic without an antenna even connected. AUX sounds great. Pots are pretty scratchy but some deoxit will fix that :yes:

Now...All the is left to do are about 5 caps towards the front of the unit. I am awaiting for my order to come in from AES and those will be fixed up leaving no old caps left in the TA-600 other than ceramics!

Here's a shot of cans installed from top and one more from the front.

Stay tuned, more to come! :thmbsp:

Kory

 

[Louie7]

Nice

 

[spaceman]

Nice work. :thmbsp: I think you'll be VERY happy you got that KM-60, I like mine a lot more than I thought I would. And it's the perfect "upgrade" for the dual tuners in the 600.

 

[apurcell22]

Nice job Kory.

 

[kpaxfaq]

Update:

Last post I made when I had her up and running there was a problem with the balance and volume and balance pots. I applied deoxit but it did not seem to help. There were still caps in the front end I hadn't replaced yet. It was shut down and I didn't touch it until suddenly feeling motivated again last night.

I replaced the remaining 8-9 caps in the front end of the unit, tied her back up and applied power. No more issues! FM mono really is awesome on this thing. I literally don't even need to connect an antenna to obtain full quieting on almost all stations. I also connected it to my squeezebox and was very impressed by the sound. It's different than my other Fisher receivers because it has 7189 outputs but I like it. :yes: My girlfriend isn't a critical listener and she mentioned how it sounded like the band was right in the room with us when I was listening to Pink Floyd - Shine on you crazy diamonds.

I measured voltages and they were all almost identical to the schematic.

I connected it to my MPX-100 out of curiousity. It works but sounded off compared to my KM-60. The MPX-100 hasn't been recapped so we'll see if that can cure the problems as I'm sure it has some tired lytics' in it.

I removed all the tube shields just to see the glow in the dark and it is quite impressive I'm at work now but plan to take a nice action shot later this evening. This thing is quite the spaceheater! I cannot wait to get home and play some more.

Kory

 

[kpaxfaq]

kpaxfaq:

I know this is bit premature at this stage of your rebuild but, I'm wondering about your dial glass.... The stencil on mine is perfect, yet the inside of the glass is covered with a layer of dust that's really tough to get off. I've started to remove the dial glass several times and chickened out. Bending the tangs on the dial bezel to remove the glass kinda freaks me out. The dingy glass takes away the looks of an almost perfect receiver.

dsndblm,

I am having the same dingy glass problem. My lettering has a couple faded spots in corners on an otherwise near perfect receiver. I am just going to let it ride...I'm afraid just by eye-balling the letter that it will fall off if I get near it. My KM-60's letting was very robust and I was able to lightly scrub the whole thing with newspaper/warm water. I cleaned the front of the glass and we're going to leave it at that....

Kory

 

[kpaxfaq]

Here is the bias supply mod we talked about in the other TA thread. Per Tom B 10-03-09
"If you have the Sams schematic, what you want is the 15K resistor R162 - lower it to reduce the idle bias. Adding 220K in parallel will give 14K, 100K in parallel will reduce it to about 13K, and will reduce the current proportionally. 12AX7s should be OK at 20-22V on the heater."

I noticed that you are using a 6X4 rectifier for the lower voltage B+. I'm almost certain that the TA-600 uses a 6V4 for that position. Mines does, all schematics I've seen reference the 6V4

Great thread!

I've now developed a further understanding of cathode bias. I read in another post of yours that a stock TA-600 runs the 7189's at a blazing 45ma. I think I'm measuring right but I'm getting around 22.5V on the cathodes divided by 680ohms gives me 33ma/tube which is perfectly acceptable for cathode bias and exactly where my Pilot 602 runs it's 6bq5's at. Let me know if I'm mis-measuring something I am always looking to be edjumakated!

Did I mention this thing sounds awesome!

 

[kpaxfaq]

As promised I finally got some action shots of the completely restored TA-600.

 

[dsndblm]

Kory,

Really nice job on your TA restoration! They are really cool old receivers, gotta love 22 tubes glowing away. What do you think of the mono fm?

Your cathode current calculations seem to be right on. I installed 10 ohm 1/4 watt resistors on my 7189 cathodes. It's an easy way to quickly check currrent. The resistors will also act as a safety fuse in case of a tube failure.

 

[kpaxfaq]

Kory,

Really nice job on your TA restoration! They are really cool old receivers, gotta love 22 tubes glowing away. What do you think of the mono fm?

Your cathode current calculations seem to be right on. I installed 10 ohm 1/4 watt resistors on my 7189 cathodes. It's an easy way to quickly check currrent. The resistirs will also act as a safety fuse in case of a tube failure.

Thanks for the reminder! I ordered a ton of 10 ohm resistors last time just to have around. I'll add those in next time I move the beast. I've also planned to add some tip jacks to the one of the vent holes next to each OP so I can easily check at anytime. I want to do this with all my amps. With my fixed bias Fishers I want to remove the cardboard can once I bypass it and put the adjustable bias pot there for easy bias adjustments.

Honestly I now get how people think mono FM is better. I don't enjoy it as much with rock music that makes a lot of use of the stereo effect but for my local classical and jazz station which I listen to 95% of the time it sounds fantastic and rich. I alighnment of this thing seems dead on. I don't even need an FM antenna connected for reception! I have a simple dipole connected now and it's great. I briefly hooked up my MPX-100 which is unrestored and while it worked I wasn't pleased but once I recap that I'll give it a fair shake. I really don't miss MPX-stereo that much which this though I'm tempted to sell the MPX-100...Part of me enjoys they were made to be together though and might just keep em' together as a set for my own little Fisher Radio museum


AM in nice as well for baseball but I need to build a loop of some sort because I'm not happy with the Ferrite antenna's performance. It is fine for local station (although not quite as quiet as I'd like) but frankly sucks for anything out of town during the day that my car has no problem with like 550 out of buffalo and 760 out of detroit. Also, it stinks for any DX at night. In my car I can easily get 670 out of Chicago for white sox games. I can barely hear it in the background at home. I'm thinking a loop with tuning capacitor near the ferrite antenna will fix that up nicely.

It's refreshing to know that other than a possible bum resistor or tube, I shouldn't have to touch a thing for a couple decades to come. :thmbsp:

Kory

 

[kpaxfaq]

Interesting observation...

I've been watching TA-600's on flea bay lately and there have been several in decent shape, one most recently last night with nice shape original metal case sell for under $300 with original tubes in them...If you don't mind a few WPC less that you probably won't even notice with sensitive speakers I'd highly recommend grabbing one for a project! :yes:

I think alot of people are after 400,500, and 800's because the word is out on those. Also, I think a lot of people are turned off by Mono FM but let me tell you it is sweet sounding. I actually think for classical and jazz it sounds better than MPX-stereo. I still prefer stereo for rock though...

The AM section on these is as good as it gets as well....

Kory