It is time: The Fisher TA-600 - Printable Version
+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Various and Sundry Categories (https://philcoradio.com/phorum/forumdisplay.php?fid=37)
+--- Forum: Vintage Hi-Fi, Stereo and Audio (https://philcoradio.com/phorum/forumdisplay.php?fid=30)
+--- Thread: It is time: The Fisher TA-600 (/showthread.php?tid=16481)
+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Various and Sundry Categories (https://philcoradio.com/phorum/forumdisplay.php?fid=37)
+--- Forum: Vintage Hi-Fi, Stereo and Audio (https://philcoradio.com/phorum/forumdisplay.php?fid=30)
+--- Thread: It is time: The Fisher TA-600 (/showthread.php?tid=16481)
RE: It is time: The Fisher TA-600 - Ron Ramirez - 04-21-2017
Mondial
http://www.audiokarma.org/forums/index.php?threads/ta-600-service-bulletin-early-version.676168/
They begin discussing the IBAM mod on page 3, and then you can see the schematic on page 4, post #66.
I haven't built mine yet. I spent last night studying the AudioKarma thread linked just above, looking at the PC board I have and the trimpots I bought, and starting to figure out just how to go about building it. I hope to start working on it tonight or tomorrow.
RE: It is time: The Fisher TA-600 - Ron Ramirez - 04-21-2017
Here's what morzh was referring to, I believe:
http://www.stereophile.com/news/052206tubes/#LmU5z6a2lrHc5SHc.97
RE: It is time: The Fisher TA-600 - Ron Ramirez - 04-21-2017
Regarding what morzh was referring to (the attempted takeover of the Saratov tube plant)...reminds me of American mob action in the movies...
"Yer tube factory's MINE now, see?"
RE: It is time: The Fisher TA-600 - morzh - 04-21-2017
Well,
Russia usually follows in America's footsteps. Sometimes 25--20 years later. Sometimes more like 80-90 years later.
RE: It is time: The Fisher TA-600 - Ron Ramirez - 04-21-2017
Back to work.
[Image: http://www.philcoradio.com/images/phorum/TA600/ta600_027.jpg]
The new 0.1 uF 600V coupling caps take up much less space than the original 400V caps did.
Tomorrow...a few more mods to make...I shall attempt to replace the final small electrolytic...and then the IBAM board gets built and (hopefully) installed.
RE: It is time: The Fisher TA-600 - gregb - 04-21-2017
Ron, If this was mine I would go through it and if there are any ceramic disc caps directly in the signal path I would change them out for poly caps. Ceramics aren't the best for sound quality, there may not be any but I would look.
Gregb
RE: It is time: The Fisher TA-600 - Ron Ramirez - 04-21-2017
I assume you mean audio signal path (i.e. audio coupling caps)...i will look...
RE: It is time: The Fisher TA-600 - morzh - 04-21-2017
They are said to cause microphonics, but I kinda doubt there are any in the audio signal paths. Fisher folks knew their basics.
RE: It is time: The Fisher TA-600 - gregb - 04-21-2017
Yes I meant audio signal path. And Mike you may be right but I would still have a look.
Gregb
RE: It is time: The Fisher TA-600 - Ron Ramirez - 04-22-2017
This morning's TA-600 surgery resulted in the final small electrolytic finally being replaced (center of photo):
[Image: http://www.philcoradio.com/images/phorum/TA600/ta600_028.jpg]
That was fun. NOT. A 390K resistor was also replaced that had increased in value to 435K.
I still want to perform the low and high filter mods posted by Dave G. in this thread, but I might build the IBAM first. The remaining mods are going to require some serious digging into tight places. To top it all off, I noticed a couple Black Beauty caps deeply buried in there. UGH.
RE: It is time: The Fisher TA-600 - morzh - 04-22-2017
Who said it all has to be easy?
If it were, any Joe Schmoe could do it.
But with all this, only a particular kind of Joe Schmoe, like us, has enough resolve to mess with this mess.
I drink this last sip of Pilsner Urquell to these folks!
RE: It is time: The Fisher TA-600 - Mondial - 04-22-2017
What do the Black Beauties look like?
Are they the Bumble Bee style or the later version with red lettering? If they are the red Sprague 160P's then they are molded Mylars and should be fine as is. If they have yellow printing, they are paper and will be very leaky.
RE: It is time: The Fisher TA-600 - Ron Ramirez - 04-22-2017
At the workbench:
Pyramid. Yellow printing. Photos later. I have replaced them, and have done 1/2 of Dave Gillespie's low-high filter mod. While it was not easy by any means to replace the Pyramid Black Beauties, it was easier to do than I thought it would be.
RE: It is time: The Fisher TA-600 - Ron Ramirez - 04-22-2017
Taking a break. Photos:
First, one of the two .002 uF Black Beauty caps still in place, partially hidden:
[Image: http://www.philcoradio.com/images/phorum/TA600/ta600_030.jpg]
and after replacement with a new .0022 uF mylar cap (it is burgundy, center of photo):
[Image: http://www.philcoradio.com/images/phorum/TA600/ta600_031.jpg]
And on the other side, the replacement:
[Image: http://www.philcoradio.com/images/phorum/TA600/ta600_029.jpg]
Dave Gillespie's low-high filter mod complete on one side:
[Image: http://www.philcoradio.com/images/phorum/TA600/ta600_032.jpg]
Next, I shall try the receiver out to make sure it still sounds OK, then I will do the low-high filter mod in the other stereo channel.
I'm saving the IBAM for last because the work I have been doing this afternoon is more difficult than the IBAM mod will be, and I had decided to get the really hard stuff out of the way first.
RE: It is time: The Fisher TA-600 - Ron Ramirez - 04-22-2017
...so...
I did the low-high filter mod in the left channel...
tried it out...
and found that I had lost my left channel.
All connections are correct, so later I will get out the old signal tracer and see what is going on.