#1
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To variac or not to variac?
...well, I guess that is my question.
Would y'all recommend using a variac to bring up an early-80s solid state TV that hasn't been turned on in about 20 years? And if yes, are there any special increment/monitoring considerations to follow while doing so? I have a decent amount of hands-on electronics experience, but only recently delved into the wild-and-wacky world of CRTs (just the solid state stuff). So basically, feel free to assume I know *nothing* I'm here to learn! |
#2
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It will NOT hurt anything--epecially since an early-80's set is nearly sure to be HOT, but if the set worked ok when it was put away...and if it was stored in a climate-controlled environment...it might not need it.
I just grabbed a 1989 Sears-Sanyo set, that has NOT seen much use. (ONLY....because I worked on then when they were brand new, so I have a "soft spot" for them). jThis one is a COLD set, with an SMPS supply, and full A/V I/O . It worked PERFECT (BW snow, anyway), NO vertical problems I can see, tube seems perfect. I did not bring it up soft, I just "let it fly", where it was when I decided to take it. SO--if you have a variac--go for it. Start at 75V, and see if the current is ok, AFTER it does degaussing. A set like that should not draw more than maybe 1.5 A, Maybe less, once everything is up. IF you see something like 2.5 to 3 a at 75 volts and it does NOT seem top drop if you got up just a tad....you DO have a problem. Last edited by rca2000; 11-05-2015 at 10:34 PM. Reason: Add info. |
#3
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Awesome, many thanks for all the info. I'll run with your suggestions and let you know how it goes. It's an '81 GE, allegedly working when stashed away, but no idea how it was stored... so better safe than sorry.
Nothing at all wrong with that - as a young end-user of sets like those when they were new, I've got a soft spot as well! |
#4
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Never hurt a SS set with a variac. There are a few Sonys I
would never risk it on though. First unplug the degausing coil so it dont give bad current measures. If non-remote start at 75 V watch the current. Be sure it dont go above abt 2 A. As it warms up it will drop a little. As you slowly turn it up the current will go down & on almost any SS set be about .75 A at normal line & picture. If a remote you have to keep trying the on/off til the relay closes. Watch the current as you do it. Sometimes you gotta go fairly high to get it on. Newer sets may need other tricks to do it. 73 Zeno |
#5
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Likely not necessary.
I found a Motorola from 1965 and was advised here that using a variac on it was not necessary. Sure enough it came up without a problem. I think once you get into 50's ea sets with older style capacitors is when a variac becomes necessary. |
Audiokarma |
#6
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Agree 99%. I would not hesitate to power up a set from the 60's on
AFTER a good visual unless it were a very special set. BUT my teacher job kicked in. Since bringing up a modern set with a variac is MUST KNOW stuff to trouble shoot hoz / hv / ps problems its a good exercise to try it & see whats normal. So it may be a waste of time but it is well spent learning time. 73 Zeno |
#7
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Thanks for the insight and suggestions. Sorry for the slow reply here... finally had some time to get my hands dirty today. Started with 75 VAC on the mains, and just like you guys said, current spiked for a second while degaussing and then just hung out around 0.5 A. Sound came right up, so I dialed up the line voltage and after adjusting VHF tuning - voila, bright white snow. It's ALIVE.
I knew a variac is a must on most pre-'70s audio stuff just due to the filter caps, but wasn't sure how it'd work on an "ancient modern" CRT. Good to know now, and yep, definitely a good exercise to perform. Appreciate the help! |
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