[Ron Ramirez]

After procrastinating for two (or has it been three?) years...I decided that it is time to do something with my prized 1959 The Fisher TA-600 stereo receiver.

History

The Fisher TA-600 (TA stands for tuner - amplifier) came out in early 1959, and was Fisher's first integrated tuner and stereo amplifier all in one (heavy) package. Built before an FM Stereo standard had been finalized, it not only has a jack for an FM multiplex adapter, it was also built to accommodate the combination AM - FM stereo broadcasts which were available in some markets. This consisted of a radio station broadcasting one stereo channel on its AM transmitter, and the other channel on its FM transmitter. The TA-600 could be set to receive both, and AM and FM tuning are independent of one other for this reason.

In other words, without a multiplex adapter, FM will be received in mono. But this receiver does have a true stereo amplifier.

It uses 22 tubes and is rated at 20 watts per channel.

[Image: http://www.philcoradio.com/images/phorum...00_001.jpg]

[Ron Ramirez]

Disassembly

The receiver is held inside its metal (!) cabinet by the four screws which go through each of its four rubber feet. There are also four small wood screws underneath; don't bother removing these as they only hold two wood strips which help to hold the TA-600 in place inside the cabinet. It is the four long machine screws which pass through each of the four rubber feet which need to be removed in order to remove the receiver from the cabinet.

Once this is done, the receiver may be pushed and pulled from the cabinet.

[Image: http://www.philcoradio.com/images/phorum...00_002.jpg]

Here is how it looks outside the cabinet.

[Image: http://www.philcoradio.com/images/phorum...00_003.jpg]

[Ron Ramirez]

The front panel is made of brass. The panel on my set is in excellent shape with only a few minor scratches.

I want to keep it that way, so I pulled the knobs...

[Image: http://www.philcoradio.com/images/phorum...00_004.jpg]

...then removed four nuts on the FM tuning, AM tuning, bass and volume shafts. Once the four nuts were removed, the front panel pulled right off and was put away for safe keeping.

I wanted to remove the dial glass also, but the brackets holding the dial glass do not appear to be easily removable - each bracket is held in place by tabs which are folded over in back of the face plate.

So...I will just have to be extra careful

[Ron Ramirez]

A look at the top of the chassis:

[Image: http://www.philcoradio.com/images/phorum...00_005.jpg]

The bracket which holds the AM ferrite rod antenna is made of plastic, and was broken in shipment to me. I will glue it back together with epoxy, and I will put a piece of plastic across the back of the broken area to give the bracket extra strength. I will probably do that when I am close to being finished with this unit.

[Ron Ramirez]

A look underneath.

[Image: http://www.philcoradio.com/images/phorum...00_006.jpg]

Question:

Would you recommend replacing the brown molded Mylar caps, or leaving them alone? (They look like Orange Drops, only brown.)

All of the electrolytics will be replaced.

I will also replace the line-to-ground "Black Beauty" death cap.

I did not intend to bother the ceramic caps.

[Ron Ramirez]

Let's talk tubes...

I spent some quality time with this receiver next to my Heathkit TT-1 mutual conductance tube tester.

Unfortunately...nine of its 22 tubes test bad (extremely, extremely weak). A real shame, because until this afternoon it still had all 22 of its original Fisher branded tubes.

One of the nine is the 5AR4/GZ34 rectifier.

One 6AU6, two 6AQ8/ECC85, one 6AJ8/ECH81.

And...naturally...all four 7189 output tubes. $$$



Mike (morzh), a question. What's your feeling on 6П14П-ЕB (6P14P-EV) Russian tubes? And Sovtek tubes in general? I've already been looking at Jim McShane's site, and he recommends Sovtek EL84M while mentioning the 6П14П-ЕB as "well-known, well-liked, and now scarce". While I will most likely buy a matched quad of Sovtek EL84Ms from McShane, I see that I can get the 6П14П (no mention of the EB, does that matter?) for less $$ from Russian and Polish sellers. Your thoughts?

[KCMike]

  while listening to the Fisher 800B. Good luck.

[Mondial]

Ron, does the TA-600 have the selenium rectifier bias and DC filament supply like the later models? 

If it were mine, I would leave the mylars alone. As you said, they are some other manufacturer's version of the Sprague Orange Drop.

 Pretty much all the US cap manufacturers of the time bought their Mylar film from the same supplier ( Dupont),
so quality should be comparable to Sprague. I have tested several brands of the early dipped Mylar caps and they all test the same, with very low leakage. I have a bunch of NOS dipped Mylars of the same type and have been using them as replacements for years without a single problem

[Ron Ramirez]

Mondial

The TA-600 uses hollow state rectifiers - two of them (5AR4/GZ34 for the amplifier section; 6V4 for the tuner section). No selenium rectifiers that I can see on the schematic. The 500-S and TA-800 were the first to use solid state rectifiers. The use of solid state rectifiers was continued into the 500B, 800B, 500C and 800C (as well as the 400, I believe).

Two of the 12AX7 audio amp tubes obtain their (DC) filament voltage from the 7189 cathode bias. The other two are tied into two of the three AC filament strings.

Thanks for your advice on the mylars. It looks like it would be a nightmare to get to some of those. It will be bad enough replacing the electrolytics.

[Ron Ramirez]

An observation: My TA-600 is serial number 459xx, so it is a later production set and may have been built in 1960. I have read that some TA-600 face plates have a date stamped on the back of the face plate. Mine doesn't.

I have the proper original Fisher service manual for serial numbers 40001 - 49999. It came with the receiver.

[morzh]

Ron

6П14П is a full analog of EL84 and is a good tube. I have no experience with post-soviet era tubes.
My Melodiya radio I grew up with had that tube and the last time my dad changed it was when I was 4 or 5, I still remember it. Since it worked till we left when I was 28, and we gave it to someone.

[Ron Ramirez]

Good enough. So...I just bought a quartet of 6П14П tubes from a USA seller. $22.99 (used, tested, matched) was more palatable than $79.50 for new Sovtek EL84M tubes.

In fact I've bought all of the tubes I need now. I already have some spare Chinese 6E2 (replacement for 6FG6/EM84, recommended by someone at AudioKarma) in case any of mine go bad, but the EM84s in the TA-600 are still bright as is the one in my Fisher 400.

Still need to buy electrolytics, and I'm leaning toward new Hayseed Hamfest cans rather than attempting to rebuild the ones I have.

[rocketeer]

Ron, you might want to consider using a bucking transformer to power it. I use one to power my 1958 Fisher (14 tubes). They were spec'd to operate from 105v to 125v. Many, if not most, areas of the country are running close to that with the occassional surge surpassing it. Locally I'm getting 123v with spikes to 125v. The bucking transformer drops it to about 110v with a significant reduction in heat coming off the chassis. That reduction in heat will prolong the life of the components, most notably the tubes, especially the output tubes. There is no loss of performance.

I use a Radio Shack #273-1511B, 3-amp (I bought a bunch of them). It bucks about 12.6v.

[Ron Ramirez]

Larry

Thanks. I do have a bucking transformer. I'm not sure at this point just how much I will be using the TA-600 once it's up and running.

Around here, the AC line averages 125 volts with occasional spikes to 126.

[gregb]

Hi Ron:
In talking with a few different audio guys in the past they say best of the Russian output tubes are the ones in the link below. I have bought number of them from this fellow and have had good luck with him and the tubes are NOS and do sound really good to me and the prices are right as well. I have a few customers that ask for them specifically so others agree with them as well and they are a fraction of the price of RCA7189's.

http://www.ebay.com/itm/6P14P-EV-EL84-71...Sw241YdRbh

Gregb