Hey guys, a friend gave me a Zenith System 3 27" TV, with a manufacture date of January 1990. When I plug it in, a green LED labeled "Stereo" starts blinking nonstop. When I push the power button, nothing happens. If I hold down the power button, I hear a click inside the TV, the green LED stops blinking for a split second, then the LED starts blinking again and nothing happens.

Any ideas? I'm OK at soldering, good at following instructions, and have a multimeter. This TV is old to me (I'm only 15) but it's kinda cool-looking, but I'd love to fix it. It's sorta cool having a TV older than you.

What's the model number? I'll look and see if I have a diagram on it. It sounds to me like bad capacitors in the power supply.

The model No. is:
SF2589W

1990 sounds awful new...then I get doing the math. I graduated in '90. That TV is now 17 years old. When I was 15, a 17 year old set was a '70 model...hmmm, that's just the age set I was dragging home!

I'm sure no expert on sets this age, but caps are the place to start. Good luck!

I pulled the Sams Photofact on your set (2811-2) and I see that you have the dreaded "dual module monster" chassis. However, there is a capacitor in the power supply that has a high failure rate and can cause the problems you're having. Looking at the back of the set, you will notice two large boards next to each other. The board on the left is the main module. The board on the right is the power supply / sweep module. On the far left hand side of the power supply module; you'll notice a large electrolytic capacitor (680 uf, 200 v) Now, look directly behind & to the right of that capacitor and you'll notice another smaller capacitor (100 uf). Directly to the right of this cap is an 8 pin IC (ICX3401). I have seen that 100 uf cap bad several times. Take note that this is a polarized capacitor and the new one must be installed just as the old one was. Electrolytic caps can and will explode if installed backwards. If that cap does not do it; let us know and we'll see what else we can come up with. BTW, if you have access to a CRT tester; check the picture tube. '90's Zenith tubes don't hold up that well and it would be best to know what condition the tube is in before you dig into the power supply too much. I use a B&K 480 CRT tester. If you can find a B&K 467, 470, 480, 490, or a sencore Sencore CR70 tester; you might want to get it if the price is right. These are often on ebay at a reasonable price.

Hey guys, thanks a ton for the info. Unfortunately, I won't be able to get into the set until late tomorrow or Friday afternoon (due to the astronomical amount of homework my merciless teachers have given me), but I'll be sure to take pics of the TV and the chassis. Is the 100 uf cap available locally (Radio Shack)?

Thanks for the help!

This sounds like my main set, which I would call the end of the line for 'good' Zenith sets. Mine had the same problem, and same fix. Great picture if you can fix it, much better than any recent crt junk.

Yes, you should be able to get that 100 uf cap at Radio Shack (of course, you'll probably have to find it yourself since most of the dorks working there now don't even know what a capacitor is). You should also be able to get one from any electronic parts house (if you still have one left in your area). Just make sure the working voltage of the new cap equals or exceeds the working voltage of the original. Even though those chassis could sometimes be a pain to fix; I'll still have to agree on that set being one of the last decent Zenith's. If the CRT is still good; it will probably last a long time.

Yeah, Radio shack should have 100UF caps. God help you if you need something a bit less common though. Usualy the Radio Shack person will scratch their head, then try to sell you a phone.

I had a Radio Shack salesman try to sell me a new digital multimeter back in the early '90's when all I ask him for was a connector so I could make a probe for a VTVM I had. Radio Shack has gone down the toilet since the 80's and early '90's. Back then, I could walk in and say "I need..." and the employees knew exactly where to look.

Those Zeniths are good sets. I liked how they standardaized the chassis. Once I upgraded a 20" set with a video board from a larger set (added s-video and some other features).

Radio shack is a pain because they still ask what you're looking for as soon as you walk in the door. I like to be left alone when I'm shopping.

Holy Cr@p! That was it! THANK YOU GUYS!!!!!! I had a hard time getting the old cap out (couldn't figure out which pins on the bottom of the board belonged to the capacitor on top) and I had to have my dad pull on the cap with pliers while I heated up the solder on the bottom of the board. I pulled out the old cap and headed to Radio Shack, they had a 100uf 35V cap for $1.25. The original was 25V. I got back home, put the new cap in (making sure I had the correct polarity of course!), put some solder on the pins, snipped them to the right length, put the chassis back in the case, plugged it in and crossed my fingers. The first thing I noticed was that the power LED was not blinking anymore, but completely off. I pressed the power button. I heard the CRT degauss, and then.... it worked! The picture was really dim though, but I went into the menu and the "Picture" option was halfway. I turned it up all the way and now I get a bright, colorful picture! I can see the scan lines, but text shows up a little soft. No matter though, It still looks good and the tube seems to be in good shape. I will post pictures tomorrow (my camera is charging right now, but it takes all night). I also bought an universal remote control at Wal Mart for $8 and it works great!

Thanks a ton to everyone, but especially to radiotvnut. Without your instructions, I would have never been able to fix this set. Amazing how many decent "broken" TV's get thrown away because some $2 component inside failed.

If you're getting scan lines, that tube is probably weak.

I don't think the "bad" Zenith tubes started until about '93-ish, so maybe yours just had some serious hours. Mine saw lots of use for the first 10 years, now not as much (as TV has gotten more sucky, the set gets used less).

Glad to hear you fixed it !! :thmbsp::thmbsp:...

Here's what I did with mine:

http://img.photobucket.com/albums/v619/Chromacolor2/TVstart.jpg

http://img.photobucket.com/albums/v619/Chromacolor2/TVduring.jpg

http://img.photobucket.com/albums/v619/Chromacolor2/tvafter.jpg

Before anybody hates me, that porthole Zenith was long gone before I got the cabinet.

Glad you got it going. It would have been nice if Zenith had roadmapped those boards. I think they intended on those sets to be repaired by swapping modules. You may can play with the G2 and focus controls located on the flyback transformer (the thing with the large red wire coming out of it that goes to the crt) to help improve the picture. This set employs AKB (automatic kine bias) and has no cutoff or drive adjustments. Yes, I'll agree that there are TONS of nice TV's (both old and newer models) that are thrown away because something minor went wrong and the owner didn't want to invest any money in it. You might consider placing a wanted ad in the paper advertising "free pickup of non working TV's." I've done that over the years with good results. Here lately, all I've gotten is '80's and newer sets. I hope some tube and early solid state sets will find their way over here soon. You could also ask around your local TV shop. There's one here that gives me all their junk so they don't have to dump it. A good bit of it is fixable. They are just sets that no one wants to spend money on. The ones that are going to cost a lot of $$ to fix get scrapped for parts.

By scan lines, I mean that when I look close I can see the individual lines that make up the picture and I can follow them with my eyes as they go down. Every single tube TV I've ever seen does this, I know it's normal but I don't know what it's called. Anyway, this will become my main set. I can finally replace the Orion 13" I've been using for so long! To think I was about to buy a trash Durabrand from Wal Mart.... I knew they were garbage, but thought it was my only option for getting a large TV for my room.

By scan lines, I mean that when I look close I can see the individual lines that make up the picture and I can follow them with my eyes as they go down.

Then that's a good sign. When the CRT get weak they often get so blurry that you can't see the scan lines any more.

Hey guys, I've got the TV hooked up to cable now and everything is great, but... this TV overscans horrendously. Most logos for all the TV stations are partially cut off and the TV Guide is unreadable..... is there some adjustment I can make that will fix this?

Some TV's are just built that way. However, I'm certain there's something you can adjust or replace that will fix that.

Is the picture distorted? (Do people/things look taller then they should?)

Try adjusting R2112, the vertical lin control. It's located on the far right hand side towards the front of the power supply board. There could also be some bad caps around this control.

I seem to recall that Consumer Reports would complain about Zeniths overscanning too much. I have a 13" Zenith from the late 80s and it does quite a bit. If it's just vertical then the adjustment should handle it.

I assume you meant to say to adjust the vertical size control, not vertical lin? Do those sets even have a vertical ine control? Assuming is vertical overscan and the linearity is good, that may be all that is needed. There should also be a width coil near the flyback that will take care of any horizontal overscanning. It will be the only large adjustable coil in the set.

I have seen some other bad caps in those sets that caused excessive overscanning with poor vertical linearity. It's been a long time, but I think they were at the edge of the board near the vertical IC.

I assume you meant to say to adjust the vertical size control, not vertical lin? Do those sets even have a vertical ine control? Assuming is vertical overscan and the linearity is good, that may be all that is needed. There should also be a width coil near the flyback that will take care of any horizontal overscanning. It will be the only large adjustable coil in the set.

I have seen some other bad caps in those sets that caused excessive overscanning with poor vertical linearity. It's been a long time, but I think they were at the edge of the board near the vertical IC.

My schematic indicates R2112 as a vertical linearity control. I can't find a vertical size or vertical height control anywhere. Here are some cap suspects if adjusting this control does not solve the problem:
C2108 - 4.7 uf
CX2109 - 1000 uf
CX2110 - 100 uf
C3248 - 3.3 uf
CX3208 - 4.7 uf (bi-polar cap)

The "X" in the location number indicates these caps to be critical values and should be replaced with a cap of the same capacitance value and at least the same working voltage. Those caps in the 2100 series stand out in my mind as being possible suspects. CX3208 is a big cap located at the front of the power supply board. All the rest are located around the vertical linearity control and the vertical output IC. This IC is a 13 pin device mounted on a heatsink.

R3249 is the Horizontal width adjustment in this set. Look towards the left hand side of the power supply board. You'll see a larger size electrolytic cap. Behind the cap is a small transformer. Behind that is a small electrolytic cap. Behind that cap is the horizontal width control. Behind the control is the vertical IC heatsink.

Thanks for the suggestions! After watching TV on the Zenith for two nights, I've noticed the overscan problem is not so much Vertical as it is Horizontal. The Vertical seems to be OK, overscans just a tad bit but is still perfectly acceptable. Horizontal, on the other hand, seems to be causing the problem. I'm also getting some pincushion distortion on Horizontal. I'll try adjusting the control tomorrow, any suggestions on caps in the Horizontal section that might be bad?

Here are some pics of the TV. I'll add some pics of the chassis when I open it up to make adjustments tomorrow.

I'm almost certain there are some bad caps in the horizontal section, the picture has started shrinking horizontally for a split second and then going back to normal. I'll replace the three 2100-series caps in Vertical later today after I go to Fry's, plus any suspect caps in the horizontal section if you reply before I leave for Fry's.

Caps are cheap. I'd say replace as many as you believe are suspect.

Having a multimeter to test the caps would help narrow down which ones are really bad. Failing that, you can't go wrong with replacing suspect caps, unless you replace them with ones of the wrong value or too low a voltage rating. Your TV is pushing 20 years old. Likewise, the caps in it are pushing 20 years old.

With any Zenith, check for bad soldering. I've never seen a Zenith circuit board that didn't have at least a few bad connections. Also, look for leaking caps. Zenith sets of that age had some with bad seals. Look for a brown substance on one of the wires under the caps. You might have to remove large caps to check them. The high temperature ones are particularly bad (brown, or dark blue cases).

This is where an ESR meter would be really handy.

By scan lines, I mean that when I look close I can see the individual lines that make up the picture and I can follow them with my eyes as they go down. Every single tube TV I've ever seen does this, I know it's normal but I don't know what it's called. Anyway, this will become my main set. I can finally replace the Orion 13" I've been using for so long! To think I was about to buy a trash Durabrand from Wal Mart.... I knew they were garbage, but thought it was my only option for getting a large TV for my room.

I have a symphonic flat tube TV that is now marketed under the durabrand name that has an exelent picture that eats LCD's for breakfast butthen again its bigger than "13".

I changed CX2110, a 220uf cap behind the heatsink the 12-pin IC is mounted on, and a random 1000uf cap on the left module. No change at all, I'll replace the rest of the suspect caps you told me about as soon as I have money. One thing though, I'm buying the new caps from Radio Shack, they are Xicon caps (are they any good?) anyway, some of the replacements have the same uf rating and higher voltage ratings, but are physically smaller than the original caps..... is this normal or a cause for concern?

I think as long as the uf rating is equal to the old caps, and the voltage is equal or better, you should be fine. If the spacing of the leads is a different length then the old caps, you might not be able to get the cap flush with the board, but it should still work, as long as it's the same uf and equal or better voltage.

As to the quality of Radio Shack caps: I haven't heard any horror stories. My only gripe is their price and limited selection.

EDIT: If you could somehow get ahold of a multimeter, it would make finding the bad cap(s) a lot easier.

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.

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.

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?

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.

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.

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?

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.

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

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

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.

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.

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.

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 :D 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.

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.