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Post by mauro on May 6, 2018 17:29:34 GMT
I'm rebuilding the amplifier from my W1700 and found that the schematic calls for a 0.002 capacitor in position C4 but in the (untouched) amplifier there is actually a 0.022 capacitor installed.
Now I've read previously to follow what's in the amplifier but in this case I'm not sure as the "non-HF" model calls for a 0.022 capacitor at position C4, which is what is installed.
I'm wondering if anyone has come across this before and what the correct value would be here?
Thanks!
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Post by Ron Rich on May 6, 2018 17:43:56 GMT
Mauro,
I hesitate to make an assumption here, but it would be my guess that if you are sure the cap you found installed, is original, there was a printing error made in the schematic/parts list. Ron Rich
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Post by mauro on May 6, 2018 18:56:05 GMT
Thanks for the input Ron,
Yes, that's what I've done in the past but I'm just wondering now how this affects the circuit? I haven't learned enough yet to know how the different values will affect the amp.
At this point I will follow what's there but for education purposes it would be good know.
Mauro
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Post by robnyc on May 6, 2018 22:44:10 GMT
Mauro, that is a mistake-o in the list. ALL subsequent amps call for 0.022 in that position. Given that part is in the oscillator tank, there would not be a variation from non-HF to later since the same frequency is used with the Cobra cart.
RobNYC
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Post by mauro on May 7, 2018 1:46:45 GMT
Hi Rob,
Thanks for the explanation, it makes sense now.
I seem to find my fair share of misprints on Wurlitzer schematics, I remember doing an amp from a 2300 and found wrong values in the parts list. I followed what was in the amplifier. I don't think I've seen it in other makes? At least I dont recall.
Thanks to all, I'm about 2/3 through the amp now hopefully will complete by next weekend, now I have to find a 0.0005@1600v capacitor!
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Post by robnyc on May 7, 2018 7:39:33 GMT
Mauro, mistakes happen --even in the professional electronics service data. When I was 10 i started hanging out/working at a repair shop on my block. The owner often pointed to errors in the Photofact schematics. Later working between semesters at a co that serviced and rented broadcast eq. I often ran into prints with red pen annotations and corrections even at that level. Here is one I found in a TSA7 schematic: www.flickr.com/photos/90641375@N06/26752769278/ Toward the center you'll see my "wrong" note w/arrow. If that connection were made the amp would not pass audio. There is a minor one on there as well but I forgot where. I'll mark it up when/if i see it again. I've found several errors in the 1960's Rowe schematics including one on the MM3 preamp that had me wondering if i even understood the circuit at all. I added one dot for a connection and the circuit made sense...and that is how it actually was built. Look at it this way, we humans can screw up in ways that a computer could not understand, or correct. Kinda, makes you proud :-) RobNYC |
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Post by Ron Rich on May 7, 2018 13:32:53 GMT
Hi Guys, On the old PhonoLand forum, we used to have a section that noted "Known errors in printed material". Maybe it's time to add that here on JA ? I know first-hand that "errors" get printed. When I wrote the first version of my Seeburg MicroLog trouble shooting guide, several people "proof read" it several times, including myself-- wound up with an "errata page" I shipped with every copy. On the last printing, of my "Seeburg Mechanism Guide" before the one shipping now, some how the word "Seeburg" on the first page, in large print, became "Seeburt" ??  Ron Rich |
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Ron Rich