J
Jason D.
- Jan 1, 1970
- 0
Hi all,
F27634xxxxx, STK730 SMPS, CTC187BJ.
I decided to use bulb 135W (two bulbs) in series on the AC input in
place of fuse to prevent horizontal transistor blown again just in
case. Glad I did! When horizontal circuit starts up it gave fraction
of a second for HV and horizontal pulses then mess up instantly with
high current draw. Cycling by the visual of strobing light from
bulbs.
Checked: flyback transformer, pin circuit, redid tuner & micro grounds
(this is one of rare chassis using COPPER box for tuner! Prior to
this, I have done so many tuner jobs and it is zinc from my experience
with zinc metal & soldering), have HV as well.
Had scope on the base of HOT, I got good pulses for a fraction of a
second (several cycles) just once strobing kicks off once waveform
distorted with high frequency noise in off cycle times at that point
bulb lits up and chassis loses power then get power back again, loses
power again as it tries to run horizontal. Cycle goes on.
Checked the flyback transformer outputs with scope as well and can get
nice good waveforms several cycles for fraction of second then
distorts, after that point just the bad waveforms as long as bulb
strobes. Had to unplug then plug again to get that clean fraction of
second waveforms.
Makes sense?
Cheers, Wizard
F27634xxxxx, STK730 SMPS, CTC187BJ.
I decided to use bulb 135W (two bulbs) in series on the AC input in
place of fuse to prevent horizontal transistor blown again just in
case. Glad I did! When horizontal circuit starts up it gave fraction
of a second for HV and horizontal pulses then mess up instantly with
high current draw. Cycling by the visual of strobing light from
bulbs.
Checked: flyback transformer, pin circuit, redid tuner & micro grounds
(this is one of rare chassis using COPPER box for tuner! Prior to
this, I have done so many tuner jobs and it is zinc from my experience
with zinc metal & soldering), have HV as well.
Had scope on the base of HOT, I got good pulses for a fraction of a
second (several cycles) just once strobing kicks off once waveform
distorted with high frequency noise in off cycle times at that point
bulb lits up and chassis loses power then get power back again, loses
power again as it tries to run horizontal. Cycle goes on.
Checked the flyback transformer outputs with scope as well and can get
nice good waveforms several cycles for fraction of second then
distorts, after that point just the bad waveforms as long as bulb
strobes. Had to unplug then plug again to get that clean fraction of
second waveforms.
Makes sense?
Cheers, Wizard
