View Full Version : A shamefull goof-up


dieseljeep
07-11-2017, 10:17 AM
I bought a Sony CRT Watchman with the paddle style CRT. IIRC, that's what they referred to the design.
I was experimenting with a lighter socket power cord that fit the auxillary power jack. The Sony has the center terminal negative, so I connected the power cord reverse polarity. I should've checked the connections on the power cord, as it turned to be the proper one, with the center terminal negative.
I tried the set with Dollar Tree "C" cells and it worked rather well. After reverse polarity damage, the display is now trapizoid shaped. It must have a different type of horiz scan circuit, because the yoke couldn't be damaged under those conditions. I'm not going to try to repair it.
I'll try to be more careful, next time, which I usually am. :sigh:

Electronic M
07-11-2017, 10:24 AM
At least those are not unobtanium sets....I've had ~4 come through my hands from a few years of thrift shop visits.

It may not be too hard to fix the trapezoid issue. IIRC the geometry of the CRT design required some amount of vertical rate modulation of H width...There may even be a service control for it.

BigDavesTV
07-11-2017, 12:08 PM
I always let my meter precede me, to double-check the triple-check for proper voltage and polarity, before I connect, even when I'm sure I have it right, lesson learned years ago!

zeno
07-11-2017, 03:38 PM
Those sets were heavily SMD'd. Trapizoid raster was a common
problem on the Sonys & Zeniths BUT I never knew what it
was. We had the customers send them to Sony & the Zeniths
we took to the Zenith distributor.
My guess is under the circumstances...........
1) data in an e-prom corrupted
2) a dead supply.

good luck
Zeno:smoke:
LFOD !

BTW measure twice, cut once !

Jon A.
07-11-2017, 04:08 PM
Ah, that old mistake. Join the club, we've got jackets.

maxhifi
07-11-2017, 04:45 PM
If that's the worst thing that happened this week, you're still having a good week! I know of a guy who did that to his car! (Results not good!)

centralradio
07-12-2017, 02:04 AM
Too bad sorry to hear this. Leave it to the idiots that want things different then having a standard polarity having positive center pin and negative outer conductor. I always refer to these CRT's ."lollypop tubes".I got to sets here.

I dont know what model number you have .I found these service manuals online.

http://freeservicemanuals.info/en/servicemanuals/viewmanual/Sony/FD20AEB/None/None/WATCHMAN/

https://www.manualslib.com/manual/1060991/Sony-Fdl-22.html?page=12#manual

https://www.manualslib.com/manual/850892/Sony-Fdl-250t.html

http://hackaday.com/2011/10/03/hack-a-watchman/

Where it says service manual.Click it for the service manual.

dieseljeep
07-13-2017, 11:10 AM
If that's the worst thing that happened this week, you're still having a good week! I know of a guy who did that to his car! (Results not good!)

That was really not the worst thing that happened that very day. My Brother called at 11:55PM to notify me that his Wife of 54 years passed away. He had the sound of relief in his voice, as it was a real tough ten weeks of suffering. I visited her the day before and she was having a difficult time.
Anyway, the set is the least of my worrys! I'm probably not going to attempt to repair it, as it not that valuable, as Tom C. stated! :sigh:

Findm-Keepm
07-13-2017, 02:11 PM
Usually there is a diode connected across the DC input for reverse polarity protection - check that first - it could be shorted and pulling down the power supply. I ran into that on one of those little Bentley sets they used to give away at time share seminars. You don't get the power adapter with the set, so most folks used a RatShack wall wart, and miswired it.

dieseljeep
07-14-2017, 11:26 AM
Usually there is a diode connected across the DC input for reverse polarity protection - check that first - it could be shorted and pulling down the power supply. I ran into that on one of those little Bentley sets they used to give away at time share seminars. You don't get the power adapter with the set, so most folks used a RatShack wall wart, and miswired it.

There's a lot of those Bentley sets around! I see them at yard sales, thrift shops, even electronic swap meets. The E-place has them listed at some really strange prices, like the things are rare. :thumbsdn:

Electronic M
07-14-2017, 11:33 AM
There's a lot of those Bentley sets around! I see them at yard sales, thrift shops, even electronic swap meets. The E-place has them listed at some really strange prices, like the things are rare. :thumbsdn:

"Well naturally a Bently TV should cost as much as a Bently car they are just as rare....I've never seen one before man. :smoke:...Wow this is good strong stuff! :smoke:" <-Average dumb ebay seller trying to make a living off of garage sales :D