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Fisher TA-600 Restoration

Mine came with 6PS series orange drops somewhat messily installed for coupling caps. I left them alone because they were working. It looks lousy though. Whenever I get around to buying the new can caps for a proper refresh I'll probably change them to something that fits better. I have no idea what it came with originally, I was expecting either the lumpy brown turd ones or ERO but pics of Ron's makes me wonder if they weren't the good brown caps like my Sherwoods use.
 
Is there a difference between the Illinois caps and the other no-name yellow film caps commonly sold by Radio Daze, Just Radios, etc. for antique radios?

Nevertheless I just ordered some 0.1 uF Illinois caps to replace the six in the back portion of my TA-600's chassis. I also ordered the parts to build an IBAM board and a few inrush current limiters.
 
Mine came with Brown Wima's, but they had so many cracks in the shell, I said the hell with it and just changed them. Difference between the IC caps and generics? They sound the same to me. I put the generics in both my early 400 and IC's in the Late model 400. Can't tell difference with sound. Unless you have a golden ear they are probably going to sound the same. I put Cornell Dublier DME's in my Stand-alone 800 and K40Y's in my 800 for the 63' Executive console, then connected to the same speakers to A/B them. I couldn't hear a difference.

My criteria for "boutique caps" if it's one of those fancy high end jobs that you can't afford if you have to ask how much, then I put better caps.... Angela, Kimber, etc. in it. If it's a vintage receiver of the TA-600 or 800c ranking, I'll put in regular brand name caps. Lower ranking get generics. Tell the truth, to me they all sound the same.The no name are probably made by Illinois or mallory but not marked as such just to save some $$ by the dealer. They are good caps, I haven't had a failure yet. Put a mkw or mkp next to one of the generics and look at the construction. They look pretty much the same, so I don't think there is any real difference between them. Maybe a little bit higher noise floor but it isn't much.

Larry
 
Larry - Thanks. I've been messing around with the real oldies (antique radio) for 43 years, but tube-type Fishers are still rather new to me, so I just wanted to make sure.

Although I have already ordered the Illinois caps, I will replace any other brown caps with my current stock of generic yellow film caps henceforth.
 
Ron; Very litle difference btwn the old stuff and the newer stuff. They all use the same parts. If something works, stick with it.
 
A lot of my yellows are no-name too. I bought them initially for radio rebuilds and used them because they were on hand. I just tend to not admit that my cheap yellow caps are really cheap yellow caps :) For whatever its worth, I have not had one fail on me yet.

One issue with some of the "boutique" caps is they're just massive. In some cases its just not possible to fit one inside a tightly packed piece of gear, and most tube receivers fall into that category.
 
I have had a failure or two when it comes to yellow film caps...but considering that I've used them in literally hundreds of vintage radios, I can't complain.

(no, not all of those radios were mine)
 
I hear ya, but when you literally have changed out tens of 100's, and only had one or two fail, 0.1% or less looks damned good on the MTBF rate!
 
...indeed...

An Experiment

So I switched V21 and V22. Last night the 6П14П tube which developed a red plate was in the V22 position.

I reconnected a pair of speakers, plugged the TA-600 into my Variac and brought it up to 115 volts again.

Result:

The red plate did follow the same 6П14П to the V21 position. However, tonight I was able to play it twice as long as last night, and when I saw red on the V21 plate, it was red in a small spot instead of the entire plate being a glowing red as it was last night.

I had the lights out at my workbench, watching for any red plates, and as soon as I saw it I turned off the Variac.
 
dcgillespie said:
That's a really super job you're doing! No doubt you'll have it going in no time.
Click to expand...

Thank you, Dave! And thank you also for all of the great information you have posted on this and other Fisher models. I spent quite a bit of time studying your TA-600 improvement thread before I started working on this one.
 
Did you install cathode resistors on the outputs? If not, you might want to do so, so you can monitor tube draw across the resistor. 1/4w metal film are fine.
 
also just a mention, the 6P14P isn't really a 7189 sub. You want the 6P14P-EV (or EB depending who reads it) for that job or an EL84M, which is the same thing wearing a Sovtek badge.
 
Larry - I have the resistors but have not yet installed them. I will do so when the IBAM parts arrive.

Gadget73 - Thanks. I had looked, without success, to see if there was a difference between 6П14П and 6П14П-EB; now I know. I have a set of four new old stock, in box, 6П14П-EB (6P14P-EV) tubes on their way to me. I see they have made it from Ukraine to New York, so maybe I'll have them by the end of the week?
 
The -EB has higher voltage ratings. I think there may be other differences as well, maybe something about rated life or altitude ratings that don't matter for terrestrial amplifiers.
 
More parts have arrived!

ta600_023.jpg


Digi-Key doesn't fool around when it comes to ordering parts. I ordered them on my lunch hour Monday; less then an hour later I received notification that they were shipping my order. Two days later, here they are. Usually when I order from Mouser, they don't fill the order until the evening after I place the order. Their shipping is just as fast, once they ship the parts.

Anyway...

Wow, those 1/4 watt trimmers are tiny! Having never built an IBAM board before, I did not know how big the board should be...now I see I could have bought a board about 1/2 the size of what I purchased (2" x 2").

The next big question...where the heck do I place this board, and what do I do to hold the board in place? The "where" seems pretty obvious...as close to the output tubes as possible...but the "how to hold it in place" I find sort of puzzling at present.
 
I have the opposite experience, stuff from Mouser gets here faster. I think it may just depend where you live. I have no complaints about either one though.

My board was stuck in with double sided foam tape, but that didn't really hold very well. Been meaning to try some better tape, the stuff I had was old junk that was laying around. I also covered the back of the board with hot glue for insulation purposes, possible the hot glue doesn't jive with the foam tape too well.

Its living over near the cap under the chassis, in that bit of space between the cap and the terminal strip near the output tubes. Mine is a long rectangular board with the trimmers side by each rather than in a square sort of pattern. I don't know that it matters a bunch honestly but for me its easier to keep track of when the control layout sort of matches the tube layout. I buy PCB in 4x6 or whatever size sheets and just cut out a hunk as needed. I don't use tons of it, but I do use enough to justify keeping a piece on hand for stuff. I actually used to get it from Radio Shack, but they are no more.
 
With small quantities, those anti static bags are costing DK more than the parts. Don't know why they need them for capacitors, let alone mechanical parts. Recent order was in house for 2:05, order received to shipped, now has made it to Twin Cities in 2 days. Probably one more day to Chicago, then out for delivery. Much slower than usual, but I'm not in a hurry.
 
Oh, no real complaints about Mouser from me either...I only find it odd that when I place an order, say, on a Sunday; they usually do not fill it until Tuesday evening. Maybe it has to do with Blue Monday. Who knows. But overall, yes, Mouser has been good to me.

Hmmm...double sided foam tape...interesting. I was wondering if something like that would hold. That R19 is like a heater. Man, the underside of this chassis really gets HOT where that resistor is! Because of that I'm concerned about foam tape holding an IBAM in place. Now that I see how tiny the trimmers are, I'll cut the board down to just the size I need, and I have a fair smount of space in between R19/R26 and the two terminals that I cut off a longer terminal strip, where the ends of the original R19 and R26 once connected - I had not yet cut off those two terminals when I took the picture below:

ta600_009.jpg


I'm now sort of regretting my placement of the new R19 and the new R26. Originally R26 was closer to the insulated can electrolytic; when I put in new terminal strips, I placed R19 closer to the can to get them away from the long terminal strip behind the output tube sockets where four small ceramic disc caps are located. Nevertheless, it is fairly tight quarters under there and R19 is going to produce a lot of heat regardless of where I place it.
 
Ron; I use a 2"x2" board so I have room for a 1" metal standoff, that is mounted on a screw thru an existing hole near the 1st tube off the Main filter caps. That takes care of the IBAM, gets it off the existing components and I don't have to worry about sticky crap all over the place.

On the 600 I did use double sided tho because of the height restrictions.

Don't worry about R19. It's fine there and the caps and other components don't seem to be affected by it. Mine is a 50xxx series so it has the twin 280ohm resistors. I used a 150ohm 20watt in place of them and it runs just fine. Placed similar to your;s. I placed IBAM at left side of R19 and wired it so all wires are coming off the left side of the board (away from R-19) all is fine.
 
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