Both 110 and 111 are both 5V rail connections
Ah, I only saw 111 on the snippet of diagram Chris posted.
Are there any blue (but now looking a bit brown!) tants on the logic board?
Both 110 and 111 are both 5V rail connections
Ah, I only saw 111 on the snippet of diagram Chris posted.
Are there any blue (but now looking a bit brown!) tants on the logic board?
There aren't any decoupling tants I believe, from what I can see apart from the 74xx ICs there very little to cause a short on the rail. Chris should be able to find it fairly easily.
John.
Quite - I looked at the circuit, thought "there's precious little decoupling on here" and then thought "well, it's down to removing one chip at a time from the board until the fault clears". I'm not sure, but I think I have some old-fashioned TTL in the store.
I still have some 7400s, 7490s and 555 from when I built the PW Tele-Tennis back in the 70s
John.
Well it's none of the ICs, on the PCB. I think there is one in the huge brass can, I've not checked that,
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Okay, didn't see that coming.
I think it's C552
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Yep C552
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No wonder the transformer was protesting!
Just glad I never ran the set for more than 5mins when I was chasing the chroma fault. The TX looks OK, hope it has not stressed it. Maybe the remote will work now once this is fixed.
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Houston, we have established signals. 👍
I tried pushing all the buttons on the remote, and the pulse on the scope varies. I'm going to put this back in the TV, and see what happens before I make any assumptions.
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I'm surprised the 100mA fuse in the transformer primary didn't blow - it is still 100mA, isn't it? I see the transformer has a thermal trip too, so no harm done it would seem.
it is still 100mA, isn't it?
Yes 👍
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By the way, yesterday you said I should bin the UDL14, instead I decided to mount it as a trophy. 😎
![20220815 161704[1]](https://www.radios-tv.co.uk/wp-content/uploads/wpforo/attachments/884/12582-202208151617041.jpg "20220815 161704[1]")
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I approves 🤣
For completeness to document the repair, 31-parts replaced to get this far.
The rogues gallery.
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It could be argued that it was less than that - how many of those orange electrolytics actually test as faulty?
Hey-Ho, I was being a tad optimistic thinking after finding the short-circuit cap, the ultrasonic side of the TV would now be functioning. Despite seeing those different pulses from the remote last night, once the receiver was back in TV, it still does not activate any functions.
On the plus side, the TV is still working. Back to the drawing board.
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Time to get that unit back out and work on it, then 👍
It could be argued that it was less than that - how many of those orange electrolytics actually test as faulty?
I might be tempted to re-form them, and if tested ok, keep any good ones for future spares.
To understand the black art of electronics is to understand witchcraft. Andrew.
