1990 Zenith System 3 - Page 3 - Videokarma.org TV - Video

karmaman · #31 10-07-2007, 11:32 PM

I have a digital Multimeter! Just tell me how to test caps! I've googled all over but can't find any decent info on testing caps. It would be great if I could test all the caps, I'm on a budget (read: allowance) so it's kinda hard for me to just randomly change caps and hope that I change ones that are bad.

MRX37 · #32 10-07-2007, 11:49 PM

Okay. Usually multimeters have a setting for testing caps. Knowing what type of multimeter you have would help, but usually one of the settings is a uf setting.

If you can figure out what setting, if any, will test caps, it's just a matter of unplugging the TV, getting to the underside of the PC board, and touch the ends of the positive and negative probes to the corresponding cap leads.

If you can't find any caps that have off readings, you might try heating up a suspect cap a little bit with the tip of a soldering iron, then re check it to see if the readings go wonky.

karmaman · #33 10-09-2007, 04:34 PM

I've only got two settings, 200uf and 2000uf. How do I test caps lower than 200uf? Also, what kind of readings should I be getting? When testing a 1000uf cap with the multimeter set at 200uf, I get 0.2. Should I be getting 0?

radiotvnut · #34 10-09-2007, 05:32 PM

The 200 uf setting is for caps up to 200 uf. The 2000 uf is for caps us to 2000 up in value. You can check anything below 200 uf on the 200 uf setting. I have seen times when the cap must be unsoldered from the circuit in order to get a correct reading. If you are checking a 47 uf cap (for example), you should read somewhere around 47 uf on the meter. If you get a much lower reading; the cap has lost it's value. If it reads way over 47 uf; it's probably leaky and should be replaced. I've seen some caps that read close to value but still wouldn't function properly in the cricuit.

radiotvnut · #35 10-09-2007, 05:37 PM

If I attempt to test a 2000 uf cap on the 200 uf range of my cap meter; I get an "OL" reading. I just fixed a 9" TV/VCR combo for a friend that would not power up. There was a 47 uf cap in the power supply. When checked on the 200 uf scale; I read about 5.3 uf. On the 2 uf scale; I read .66 uf. I got a different reading on each range. A new cap read 47 uf on all ranges except the 2 uf range (it read "OL" on the 2 uf range). A new cap fixed the set.

karmaman · #36 10-09-2007, 06:20 PM

I think my multimeter is useless, it was really cheap ($4 from Harbor Freight), and whenever I measure any of the three caps I pulled from the TV, I get 0.2 or 0.1, on all three caps. The caps are a 1000uf, a 220uf, and a 200uf. When I measure the 100uf with the multimeter on 200uf, I get 0. When I measure a 220uf with the multimeter, I get 0,and a 1000uf cap reads 0. These are all caps I replaced in the TV, but there was no change in the overscanning after swapping them out and since there were three, I figure at least one of them must have been OK.

Bad multimeter or bad caps?

MRX37 · #37 10-09-2007, 08:00 PM

Probably bad multimeter. I didn't even know they had $4.00 multimeters.

My advice is to save up and get a better multimeter. Preferrably one with several UF ranges.

karmaman · #38 10-09-2007, 08:22 PM

Well it's actually supposed to be $8, it was on sale

Can I find a decent Multimeter at Fry's? How much does a decent Multimeter cost?

MRX37 · #39 10-09-2007, 08:46 PM

My guess would be in the $20-40 range. Never been in a Fry's, so I don't know what they carry.

Before you choose a meter to buy, check to see how many settings it has. If you can, look up the model on the internet.

radiotvnut · #40 10-09-2007, 11:48 PM

Karmaman, this might be your lucky day. I was digging through my junk and found the chassis out of one of these sets. IIRC, the set had a good picture but no sound. The cabinet was very beat up on that set and I used the CRT out of it to fix another set. I never attempted to fix the audio problem. It's been sitting in my board stash; so, I can't say what it will do at the present. If you'd like the chassis for spare parts; you can have it for free if you'll pay the shipping. I can send just the power board if you'd like. That should save on shipping. If you'll PM me your zip code, I can figure what the shipping would cost.

fsjonsey · #41 10-10-2007, 12:56 AM

I love my Eico VTVM. Got it for maybe 12?? dollars on ebay. It doesn't test caps, but it does everything else. Im pretty sure the only way to accurately test caps is with an ESR meter.

karmaman · #42 10-16-2007, 10:59 PM

Hey guys, I haven't updated for a while, sorry about that. I've put this project on hold at the moment due to lack of funds, see my other thread.

@radiotvnut: Thank you so much for your offer, never before has someone I didn't know offered me something like that

Unfortunately, I have to decline, In my room I have four computers, 4 computer monitors, two desks, a bookshelf, and tons of random computer parts laying around (I'm way into computers). I try my best to keep it organized but my parents are starting to threaten throwing stuff away, they'd freak out if I brought more "junk" (at least in their eyes) in. Thanks anyway though, it means a lot to me.

MRX37 · #43 10-17-2007, 12:27 AM

Quote:

Originally Posted by karmaman

I have four computers, 4 computer monitors, two desks, a bookshelf, and tons of random computer parts laying around (I'm way into computers).

I here ya there.

I have various PCI and AGP cards, several motherboards which I have cannibalized for their capacitors, and several working computers, a couple of them using motherboards that I recapped.

I donated a good 10 or 15 slot 1 Pentium 2 CPU's to a computer recycler. Saving the Celeron 300A and a couple P3's for testing motherboards.

And monitors? Yep. Maybe 7 of em by now. People keep throwing away perfectly good monitors.

Hard drives too. Might get rid of the one's under 4 GB to make some room.