TIP: When replacing capacitors in a video monitor...

I sure would like to know what the value in the above plan is. That is absolutely the worst way to approach a monitor cap kit. Do the job one cap at a time and the values on the caps and silkscreening will all make sense and it will be apparent if there is an error with either the silkscreening or value of the item being replaced.

I dunno about that. From the way Ken describes his work he and I do cap kits in pretty close the same way. I change one cap at a time but solder them all at the same time. Have yet to miss one in 20+ years....

Matt

Matt, I absolutely agree with you. Anyone whom has done any repairs at all has made mistakes. Live, learn, move on and above all, respect electricity!

Scott C.

Matt J. McCullar wrote:

Parts count X 2 = number of joints for the job described. Sanity check afterwards: parts count X 2 = number of joints to deflux.

Preparation, you big silly. With a kit I always check the boards, use steel wool or whatever as necessary, check for obvious damage (hold it up to a light to look for cracks), etc.

We're talking about 25-30 year old monitors, I fix a lot of these, the new caps are usually far smaller physically than the old ones, plenty of modern

Not to point any fingers, but there's a few "professionals" around here who seem to have forgotten that everyone started out as an amatuer at one point or another. I wasn't born knowing anything about electronics, and I've never been formally taught, I've picked it all up on my own through doing it.

There are on a lot of things. The really fun one is the G07 chassis, they made zillions of them, one of the caps has the polarity silkscreen wrong on one side of the board, thankfully it's right on the other side, but then how do you know which one is right? Pays to make a mental note when you pull the part out.

You must have a lot of free time, or not so many monitors. When you've got half a dozen monitor chassis' stacked on the bench, any tricks to speed up the process are worthwhile. I tend to go for an assembly line approach, and change groups of 4 or 5 caps at a time on each board. Pull them all, put in all the new ones, solder them all, clip, then repeat with the next group and mark off the checklist as I go.

All it proves is he is human like the rest of us. As long as you don't make the same mistake, you have learnt something/

What little formal training in electronics I had was in HVAC school. Otherwise I like you, am self taught. I started out at the age of 14 when I noticed the barber my mom took me to had a little repair shop in a back room as a hobby. He taught me how to solder and some fundamental things. At 15 I borrowed a book from the school library, Howard H. Gerrish's Electricity and Electronics 1968 edition.I dropped out of school at 16 because I didn't want to cut my hair to conform to their dress code and got a job at a hotel restaurant. Back then you could do that at that age. I did keep the Gerrish book though and still have it to this day. That book now is 40 years old, geesh!. But it taught me about ohms law and such. And there were some transistor projects. I have to laugh at a picture in the book of a "marvel of modern technology" an IC chip made by Western Electric that rests atop the eye of a needle and has a whopping 18 transsistors on it LOL!!!!!

But to make a long story even longer I got out of the HVAC business in

Sheesh did I just type all that s*it? (Starbuck's powered this morning as usual :)

hi, i`ve know properly trained service people in public and THE MILITARY who have made much worse mistakes than that, mistakes my friends 14 yo son wouldnt even make.

hi, also , so overnight people become fully trained techs ?? i bet u $1000 that , they got interested in electronics , and made stuff ups as USUAL when starting any hobby . just because u might be a tech , does not mean YOU DO NOT MAKE STUFF UPS.

you learn from experiance .

and people CAN DO THE WORK THEMSELVES and have saved a few dollars. thats why we have fully trained techs because people start of with electronics as a hobby and make screw ups.. , and think , hey , what makes this tick , ???if i do,,,,,,,, etc..

The other good reason they warn them is to stay in business. :)

Fact is that anyone can make a stupid mistake, or in the case of the OP a very legitimate error. In my 30 year involvement with Ham Radio I know personally of a few guys that became instantly deceased by coming across the B+ supply of a final amplifier circuit that they designed, built, and used for years and years before they screwed up. Many of the tube type amps run

-W

I firmly believe that if you don't make mistakes, you never actually learn anything.

I'm not a pro, just an experienced amateur, and how I approach a cap kit depends on the chassis. For G07's and K4900 and K7000, I generally change the caps in groups because I've done so many of them. Most other monitors I just do one at a time to make sure I don't miss anything.

James

I have worked on chassis that have had the incorrect value of caps installed. (Which is why they weren't working in the first place). Honest to God, they must have had something like a 220 uf @ 160v cap in place where a 22uf@50v belonged. The person that worked on it before must have just stuck whatever cap they had sitting on the bench in whatever spot was open.

So, moral of the story...always use a cap list. Many times these have been updated with new values anyway to fix issues with particular types of chassis. The jamma fix for the G07 comes to mind. FWIW, I desolder a cap, stick a new one in and move on. Then I solder all the legs and clip all the legs. Then I look at the complete bottom of the chassis with a magnifying lamp to look for suspect soldering from previous repairs or solder splotches.

Yes, Matt knows what he is doing. I would like to repeat one of my rules I have posted before. Never do a cap kit when drunk. You're just going to have to do it again.

Pat D.

he

That ain't no s*it.....serious current at that voltage. Actually I'd think it to be a little more current for large x-mitter tubes. I pay the bills working on music equipment and a lot of that is tube guitar amps. A 500v electrolytic installed reverse polarity makes a serious racket and a huge mess (along with a rank stench) when they vent. My general rule is check polarity after replacement, then again before power up. I've never put one in backwards, but I've had 'em go postal on the bench due to excessive leakage current.....should've been monitoring the temp since they were 20+ yr old caps. I did have an amp come in once with someone else's cap job already done and a bias filter cap in backwards. How that didn't go ka-blooey I'll never know.

Actually he should have pulled off the glue-gunk to verify what came out. Going by a list and checking them off as they were replaced should've raised a red flag.

Ummmm, It's prolly safe to say that one should never do anything more technical than tying your soes when drunk. :)

-W

I've also seen a board that was marked wrong from the manufacturer.

Once upon a time, there was a PDP-11 that ran Unix, about 1975. DEC core memory was expensive, so we had a box of some third-party memory, maybe Dataram. It interfaced to the Unibus via an assembly that pretended to be a Unibus jumper between adjacent backplanes, so it didn't take any slots of its own.

One day, we had it apart, and I noticed there was a little tanalum capacitor that was clearly dead. I figured I might as well fix it, replacing it with another tantalum of the correct capacitance and equal or higher voltage rating, carefully orienting it according to the "+" marking screened on the circuit board. Put it all back together and turned on the power, and there was the smoke and smell of a fried tantalum.

So I looked at it again, and traced circuit foils from the plus and minus supply pins on the Unibus connector. (This was a 5 V bypass cap, so it connected directly to the power supply pins). Sure enough, the "+" in the silkscreened marking was adjacent to the *negative* lead of the capacitor. I installed another cap "backwards" relative to the marking, and it was fine for the rest of the life of the machine.

Dave