84 Magnavox console TV

[liammc00]

I am still pretty new to working on TVs and this looks like it is going to be a real challenge for me. I just picked up this Magnavox TV from an auction close to my house and I don't no wy I bought it as I don't have any room for it but I digress. The TV was plugged in at the auction so I truned set on and while the tube was warming up the set power cycled off and on and eventually came up to a very bright snowy picture. There also was little bit of blooming on outer side of picture so the CRT is differently got some hours on it but with britness and contrast truned all the way down you can still see raster in the bright light. Wen I got the tv home I took of the back and blow out the dust. After that I took an RF modulator and DVD player hooked it up to the set. powerd that set on and then it powered cycled a couple times( when it power cycles the led display goes off too). Once the CRT warmed up I got a picture that looks like horizontal is not locking and think the vertical was locking as well but I'm not sure as I didn't leave tv on very long. Also I got out of the speaker a loud buzz or some might call it hum adjustable with the volume control. I did not take a picture of it set on as I was afraid of causing more damage to other components. So I quickly truned the set off. The TV did have an old repair shop tage in side it. Saying that the tuner had been worked on in the past. I do know the tuners on these tvs are known for giving trouble.

[zeno]

First post the chassis number & a chassis pix of the set.
Next pull back the chassis & give it good looking over for
hot spots, cold solder joints, bulging caps etc.
You may want to post a short U-tube of the problem. Use
a live show, not cartoons.

73 Zeno
LFOD !

[liammc00]

Well the tv is kinda working on this power up. I here it ark and the tv truns off and back on. Sometimes when it comes back on it loses sync audio buzzes. After it's on for bit it behaves. As I watched a full length movie and it did not misbehave once. model number is CE4746AK02. I will porbly have to take the back off again to get the chassis model number as I could not find it on the back. The CRT is actually very strong and has a very sharp image. Also has a very loud and clear sound. Sorry about the video not being rotated correctly but I can only get the tv to misbehave when it starts from a cold start. The video still shows the problem. https://youtu.be/ck5eew48ADQ

when I have the time I will pull the back of it and give it a service

[zeno]

Looks good & strong.
To find arc pull back, turn off room lights & fire it up.
If what you hear is external you will see it.

Zeno

[liammc00]

I took the back off and gave it a look and on the top side of the board I didn't see anything that looked burnt. I also undid the for screws and lefted the board up then I looked at the bottom of the board for bad soilder joints. I didn't see anything that had any obvious bad soilder joint. When I take the board out of the set I will give it a more indept look over. Finally I put the board back into place turned the lights out so it was pitch black and turned on the set. The set did misbehave but I didn't see any thing at all but this time it only did it once. After that it worked fine. I don't know we're to start as it is intermittent and those problems are the worst to solve. Ok here some pics of the inside and here is the board ( MC2 Main Board 25C5 A10154 NC)

[zeno]

OK its a C-5 chassis. They did get cold joints in the hoz out area
& if left alone they will burn the PCB. There are a few caps going
from the E to C on the hoz output transistor & thats where most
of them went cold.
For the arc you can also use a paper towel tube as a stethoscope
to localize it.

73 Zeno

[liammc00]

I took the chassis out and connection look good but I resolder them anyway. Not being confendet that would fixs the set. I started testing components that might give trouble wile the set is cold but get better after being on. Which means I tested the caps and found out that all of the Phillips branded capes were completely bad reading in with very high esr, capacity in NF range, and very high voltage loss. There were ten Phillips capacitors in all and they were all bad. So to anyone how has a tv from this time period it seems those Phillips brand caps are garbage now. I have had to order some replacement caps as i naturally don't have the ones I need. Do to age of the set being close to 40 years old I decided to recap most of the tv as in past I had left some caps that tested good and little whileone of them blow up some expensive parts. I don't often recap stuff unless I feel it needs it.

[radiotvnut]

I fixed a number of those, back in the '90s. Cold solder joints on the horizontal driver transformer, the horizontal output transistor, flyback transformer, and on the HV capacitors are common and they often won't look bad. Sometimes, all it takes is a micro-crack in the solder joint to cause problems. Also, that yellow capacitor on the right- hand side of the board would sometimes arc and burn. I ran into a few bad flyback transformers on these and if yours ever goes, you can probably hang it up because they were NLA 30 years ago.

[liammc00]

Well I found the porblem and I'm afraid it might mean the EOL for this tv as the part that is failing is the flyback as after I replaced the bad caps and resolder all of the connections. I truned on the TV to same results but this time I had the back of and listened and I could faniltly here arcing internaly coming from the flyback. when looking at CRT while it was arcing it stayed perfectly fine. Sometimes it would arc very loud and the tv would power cycle as it was doing before. It's a shame as other then that the tv works perfectly and has a fantastic picture and the cabinet is in like new condition. I now flybacks are very fail pron but I like to know why every CRT TV I get being from 70s-2006 when it fails it is always the flyback transformer. I can never get the cheap easy repairs. I will try and get one off a junk tv or a new old stock one. If can't find one the tv will be busted up for parts

[zeno]

The C5 is a super common set so you should be able to find a FBT.
Get the numbers off the old one & from the manual.
BTW any distributors still have NOS NAP parts ??
BTW #2 C-5 was used in Maggy, Sylvania & maybe Philco so check
all 3 brands.

73 Zeno

[liammc00]

The flyback is 361969-1 and I think I might have already found a replacement one already. I'm just waiting for them to get back with me.

[liammc00]

Well scratch that off as being the flyback and no didn't replace it. I turned the seat on and ran tv for Halloween for playing music videos for over and hour. In that time the seat worked perfectly except when first turned on the TV did the exact the same thing it always dose the TV power cycles maybe once or more times then behaves fine. The tv was in garage will it was raining and very humid. The seat still worked fine and if it was the flyback it porbly would have blown up in short order. Back at square one and I'm afraid I am completely stumped as it is intermittent porblem and I have no clue what could be causing it or were to look.

[zeno]

CRT looks new so worth time.
Try tapping around when the set is NOT acting up & see
if it does it. 90% chance its a cold joint. Trouble is if not
fixed it may burn or blow out a bunch of parts in a
chain reaction.

73 Zeno

[liammc00]

I did resolder a lot of the connection but I may have missed some. I will go through it again as soon as I'm able to.

[zeno]

Its best to pull the whole chassis & put it on a bench with LOTS
of light.
Also RTVNUT mentioned a yellow cap. If its a square one they are known
to get too hot & bulge. You MUST use the right type cap or it will blow.

Zeno