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Equipment Repairs => CRT TV forum => Topic started by: E Parton on April 24, 2015,14:00:10

Title: Thomson/Ferguson TX91 10 inch portable - suspect psu
Post by: E Parton on April 24, 2015,14:00:10

It's been a while since I've had a crt TV on my bench...
This one is used as a monitor only..
I strongly suspect a psu issue ...
The red standby led takes a long time to light up ...and when it finally does pulses bright and then dim.
I have detected a faint raster on occasions ...and monitoring the supply line both on and off load (120v I think) ..
This is low around 65v and fluctuates considerably ..
I therefore suspect psu rather than anything else.
This is the set with a side mounted 12v input/invertor ..and takes 2 different leads with the required input socket sliding left or right to select.
A blast from the past but maybe one of the older generation engineers have a stock fault for listed for this ?
rgds
Evan

Title: Re: Thomson/Ferguson TX91 10 inch portable - suspect psu
Post by: downunder on April 25, 2015,03:33:14

Hi Evan,

It's been too long and I cant reboot the hard drive in my brain.

It's been a long time since I looked, but have you checked Highland Electrix. They used to have an extensive list.

If you need it, I can upload the schematic......wow, a switch mode PSU as well.             Bruce

Title: Re: Thomson/Ferguson TX91 10 inch portable - suspect psu
Post by: E Parton on April 25, 2015,05:10:08

Thanks for replying Bruce ..
Same problem for me ..
Hard to dig so deep into the grey matter drive.
I did manage to obtain a copy of the schematic in pdf form but sectionalised ...unlike the diagrams of yesteryear ..
Lots of block diagrams ..and the actual schematic carved up in sections..
Not so easy to navigate that way.
My first thoughts are to abandon the logical approach and put a cap meter on each electrolytic in the psu in turn..
maybe I'll get a result that way..
but if anyone can narrow down possible suspects this would be a plus.
cheers
Evan

Title: Re: Thomson/Ferguson TX91 10 inch portable - suspect psu
Post by: downunder on April 25, 2015,05:43:00

Hey, that stirred something within the murk. HT rail filters used to be common for this....CP80 (100uF 160V) on my schematic. You may get lucky.

Bruce

Title: Re: Thomson/Ferguson TX91 10 inch portable - suspect psu
Post by: jordan on April 25, 2015,09:37:08

TX-91

Title: Re: Thomson/Ferguson TX91 10 inch portable - suspect psu
Post by: watteau on April 29, 2015,07:48:47

Hello,
Here an Excel file contains common faults for
CRT sets, worth a look.
Regards

Title: Re: Thomson/Ferguson TX91 10 inch portable - suspect psu
Post by: astracat on May 02, 2015,13:20:10

rpo6& rpo7 high resistance was common on this chassis