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#16
04-03-2007, 10:54 PM
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Nice set. Some friends of ours had a similar set when I was growing up. It too had 3 speakers and push-pull audio. Is your audio section on the TV chassis?
Regarding the buzz, too much signal strength will also do that. Does it have an AGC pot? Maybe it's set too high. John 
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#19
04-05-2007, 02:33 AM
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Much better now
Thanks for the good words, guys. I happy with the way things turned out.
As Andy pointed out, tweaking the discriminator reduced the buzz greatly. There is still a little there... probably needs an alignment... but it's a hell of lot better now. Regarding the sound, my Philco Diamond D hits the bass really well only using one 6x4 speaker and a 6AQ5. Since this Hoffman has two 6BQ5's and two 8" speakers, I was really expecting bass response more like the Philco. Don't misunderstand... the Hoffman sounds really good for a 50's TV. In fact, I can crank the Hoffman's volume control all the way up to the stop... and not one bit of distortion! John: Yes, the audio is on the TV chassis. I tried the AGC... not much affect there... but good sugestion. Changing a couple of resistors in the verticle section fixed the occasional roll. I couldn't find the reason for the verticle being steady at the stop of the pot... everything checked well within spec... so I replaced a 1.2 meg resistor off the grid of the oscillator with a 910k resistor... and that put held the picture right in the middle of the control.
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Charlie Trahan He who dies with the most toys still dies. Last edited by Charlie; 04-05-2007 at 02:37 AM.
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#20
04-05-2007, 03:54 AM
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 Nice set Charlie--I bought a Hoffman 19" tabletop b&w new in 1960 and it was more expensive than other sets of the same size--like Whirled One said they were sold mostly on the west coast. Yours is the second one I've ever seen.Good Luck with your find.
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#21
04-06-2007, 09:35 AM
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With those speakers the Hoffman ought to have good bass. If not, increasing the size of the audio coupling caps should help. Also, be sure that the two 8" speakers are in phase, cones moving in the same direction, not one in and one out. A good way to test is with a flashlight battery (this is probably old news!)
Reece
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Reece Perfection is hard to reach with a screwdriver.
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#22
04-06-2007, 02:19 PM
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Yes, the speakers are in phase... that was the first thing I checked. It really does sound fine the way it is... I was simply expecting the same thump I get out of my Philco.
Increasing the audio couplers size, eh? Hmmm... perhaps I will toy with that for fun!
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Charlie Trahan He who dies with the most toys still dies.
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#23
04-06-2007, 04:59 PM
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Quote:
Pete
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#24
04-06-2007, 06:47 PM
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The Hoffman company is based in Los Angeles. They are now Hoffman Video Systems. However, they did have a factory in St. Louis, Missouri at one time. I have gotten several sets here in Texas and seen others in the midwest. These probably came from the St. Louis factory.
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#25
04-06-2007, 08:32 PM
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Quote:
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Charlie Trahan He who dies with the most toys still dies.
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#26
04-06-2007, 09:22 PM
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That looks like a great old TV. Hoffman made other consumer electronics. I picked up a Hoffman AM/FM transistor radio recently. In the early and mid 60's they made transitor radios powered by solar cells. Somewhat ahead of their time.
- Pete
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#27
04-06-2007, 09:53 PM
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Quote:
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Charlie Trahan He who dies with the most toys still dies. Last edited by Charlie; 04-06-2007 at 09:56 PM.
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#28
04-09-2007, 07:05 PM
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why does everyone else have all the luck... my poor 21-T639 is still sitting outside on the porch
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