Entertainment Center: TVs, Stereos, VCRs and DVDs - toshiba 40H80 RPTV Shutdown Problem
Doityourself.com community forum was created to provide answers to all questions related to home improvement and home repair. Doityourself community can help you find information about how-to topics on small fixes to large remodeling projects. With comprehensive how-to content and expertly moderated community forums DoItYourself.com makes it easy to tackle even the most complex home improvement projects.View Full Version : toshiba 40H80 RPTV Shutdown Problem
davemac2
11-18-02, 11:11 PM
I have been having a very eratic shutdown problem on my Toshiba RPTV for the last year or so. The shutdown behavior seems to be almost random. Sometimes I cannot get the set to come on even after attempting to reset the shutdown circuit by unplugging the set. Other times I can watch several movies without a problem. Sometimes I can go for days or weeks without the set going into shutdown. I have attempted to diagnose the problem by probing the over/under voltage/current circuits and cannot find anything out of spec. Also, when I remove the back cover of the set to probe, it won't fail! :confused: You would think that would indicate a temperature/tolerance effect, but the set can still go into shutdown right from a cold start. I was hoping after a few months the failure would get more consistent, but it doesn't. I have a min/max Fluke 87 DVM now which I am going to try to use to catch the fault.
Does anyone have any other suggestions as to how I can maybe make the set fail more often? I went thru the series light bulb test on the power supply, but the HV voltage regulation checks out fine there.
My suspicion is that maybe it is a bad cable between the boards somewhere or a cold solder joint.
Help! PLease! :eek:
PS. BTW, the picture and sound itself seem fine when the set actually works. I don't detect anything unusual with the picture such as convergence, blooming or anything else when it has been on and shuts down.
Dave Mc
Does anyone have any other suggestions as to how I can maybe make the set fail more often? I went thru the series light bulb test on the power supply, but the HV voltage regulation checks out fine there.
My suspicion is that maybe it is a bad cable between the boards somewhere or a cold solder joint.
Help! PLease! :eek:
PS. BTW, the picture and sound itself seem fine when the set actually works. I don't detect anything unusual with the picture such as convergence, blooming or anything else when it has been on and shuts down.
Dave Mc
FREDDYG_001
11-20-02, 12:06 AM
Tech Tip as follows:
1)Dead,Shutdown(May play ok for awhile)./Found a defective Ic Q752 convergence Ic on convergence board. #Stk392-110 part#23905094.
Still check for cracked joints on the power supply board.
Fred:)
1)Dead,Shutdown(May play ok for awhile)./Found a defective Ic Q752 convergence Ic on convergence board. #Stk392-110 part#23905094.
Still check for cracked joints on the power supply board.
Fred:)
davemac2
12-14-02, 07:05 AM
Just a followup on this problem. I finally resolved it today. It turned out to be an intermittent solder blob short on one of the OCP transistors (Q762, -15V)) on the POWER2 board. I should have inspected the undersides of these PCB boards earlier to check this when I was probing since the shutdown was so intermittent. Not too happy about the quality control of Toshiba manufacturing here. Another thing that makes me leery is all of the cabling in these sets which I would think would be a weak spot for these sorts of failures too.
Dave Mc
Dave Mc