1991 Mitsubishi CK3531R 36" console screen issue

[pac.attack76]

As u can see in the pic, the top half is flipped or pulled down. I have had this issue in the past with a couple other sets but don't remember what causes this. Any ideas?

[damen]

I think it's called the "bootstrap" capacitor. Usually connected to the vertical IC at the positive end of a diode, then to another pin on the chip.

[JohnCT]

Originally Posted by pac.attack76

As u can see in the pic, the top half is flipped or pulled down. I have had this issue in the past with a couple other sets but don't remember what causes this. Any ideas?

Most CRT TVs respond to replaced electrolytics in the vert output circuit near the output IC, but there were a few Mitsus that had other issues, but we'll start with the most likely.

1) First, start by heating the area around the vert output IC IC4E1 with a hair dryer. If the scan improves, replace capacitors C4E2 (47uf@ 25v), C4E4 (100uf@ 35v), and C4E5 (100uf@ 35v).

If that fixes it, sweeeeeeeeeet.

2) If not, measure the voltage on pin 8 of the vert IC IC4E1. It should be 29 volts. If it's low, change transistor Q4A1. (2SC2236) and diode D4E4 on the base of Q4A1.

There are a few other issues we can get into if need be, but I think the three caps in step one will fix this.

Be careful with the PC. Mits circuit foils were never particularly robust. The way I deal with older additive type PC foils is to add liquid flux to the solder of the parts to be removed. The flux will greatly reduce the amount of heat and time you need to get the solder to flow out. Use Chemwick if you have it to clear out the old solder. If you don't, use an awl to straighten the leads while the solder is liquid so you can lift the caps off the board without damaging the foils. You can use a solder-sucker if you have to but sometimes the recoil from the spring will cause the tip of the solder-sucker to impact the foil and damage it. Your call.


John

[pac.attack76]

Awesome guys. Soon as I can get in there, I'll start on it and post again