Picture "pulsates", becomes small and fuzzy

Is this happening from a cable box or DVD player?
See if other inputs don't do it t isolate the set from the input you are watching.

This is a common problem on certain models of Philips Magnavox TV sets. The most common symptom is the screen will shrink and expand over and over. After the TV heats up for a while the video will work like normal. After a few weeks or months your TV will eventually stop working and not have video. You can get complete parts and instructions from www.TvRepairKits.com

the magnifier is going

Possible cause of the problrm is bad/poor solder on the grounds for the tuner circuit shield an the bottom (solder side) of the circuit board. Grounds need a wire jumper from point to point. This was a common problem for those sets and ocassionally it would take out the eeprom chip with it. (Various other problems were shrinking picture/fuzzy picture and intermitt. power)

Inside the set you should see a large part with a red wire coming out the top. That is the flyback transformer. There will be 1 or 2 controls on the back of it. One should be labeled screen and one focus. Carefully adjust the focus one until the picture is again in focus. Please note that in that area are high voltages (33,000V) that can be dangerous. Be careful where you touch. IT is best to have a mirror so you can see the picture while adjusting the focus control.

Dan

You are changing parts in the wrong circuit. The problem is in the vertical circuit. Look for the vertical IC and resolder the pins first. It should be an LA7837 or something similar. Also, check the 100ufd and 47ufd caps in the same circuit.

Keep us posted.
Dan

the dm module power supply is developing leaky capacitors and will eventually cause the set to not come on at all. this may also be causing the snowy picture if you are useing the digital tuner. The dm module will require repair to resolve these issues.

Since the set works initially, there are likely poor solder connections at the vertical IC. If this is not addressed soon, the IC will fail and need to be replaced. The vertical IC is a small flat IC with about 11 pins or so that may be marked LA7837 or something similar. Try resoldering the pins first. If that fails to resolve the problem, replace teh IC. Feel free to post the marking here so I can verify you have the correct one.

Dan

Resolder the vertical deflection section. Change pump up capacitor if it has one...100uf is a typical value. Is the vertical output some flavor of LA783x ?? May need to replace. A model # would help.

All symptoms indicate a problem in the vertical circuit,the first thing to look for will be loose conection on the vertical output IC,sometimes this IC goes bad completly and it needs to be replaced.If you are familiar with soldering electronics you can take care of it but if you are not too familiar you can play it safe and take it to a servicer ,it will be a lot less expensive than if they come to your house.Let Us know how it goes or if you need more information.