Panasonic CT-1310M keeps blowing horizontal output transistor

[luRaichu]

I guess it's important to mention the +B measurement was taken before the recap. It may be different with fresh caps.

Originally Posted by zeno

Also the B+ control
has to go lower @125 V to put the 130VDC in range.
A manual IS needed now.

What do you mean? Last time I checked +B the lowest it could go with the adjustment pot was 130V. Max was 140V. But like I said, it may be different after the recap. I sure was foolish not to recheck +B.
I've been corresponding over email with someone who has a physical copy of the Sams' for this set. I asked them to send the part that shows the normal +B voltage and the H osc circuit.

[rcaman]

Why in the he$$ are you buying transistors from Ebay. 99% are junk

[luRaichu]

Originally Posted by zeno

HVSD a.k.a High voltage shut down.
On most sets if it activates the set goes dead. On Panny, RCA Hitachi &
some others of this era too much HV causes the H osc to go off freq.
to reduce HV. Your set is probably like that.
133 volts may be OK but you need to see if it changes. Use a variac
or go from zero brightness to full brite. It must stay the same.
Cause I have seen was always the power supply. Also the B+ control
has to go lower @125 V to put the 130VDC in range.
A manual IS needed now.

Zeno

+B is supposed to be 130v. Sams' schematics courtesy of damen.

[luRaichu]

Originally Posted by zeno

133 volts may be OK but you need to see if it changes. Use a variac
or go from zero brightness to full brite. It must stay the same.

Well I did some testing tonight and found the +B voltage floating around. It was up to 125v with a dark picture but lowers to 120v when bright. +B control resistor DOESN'T work sometimes. Sometimes it goes back to 130v and that's when the H osc. disable circuit gets triggered. I think the low voltage regulator is crapping out! https://youtu.be/OqzFIbvbYJQ

The lack of color & white horizontal dots seriously concern me. Honestly, I'm almost at my wits end with all these failures!
Considering just sending this set off to Multi Media Medic in Maryland.

[vol.2]

Originally Posted by luRaichu

Considering just sending this set off to Multi Media Medic in Maryland.

If I was seeing fluctuating voltages in the B+, I'd probably suspect one of the transistors of being flaky. Sometimes they only behave poorly when under load, and they test okay when you take them out. Usually, that will come out when you use a curve tracer, but not always. And they are pretty expensive

Interesting. I live in Maryland but I didn't know about that guy. I used to always go to a dude in Silver Spring called Danco, but he's semi retired now and he won't always take stuff in if he doesn't want to. Last thing I brought to him he sat on for six months and then said he didn't want to do it lol

[luRaichu]

Really. Everything about the HOTs I bought seemed correct - except for the fact they were of a slightly different package type. The original had a flat top but what I bought came with a bulged top.
So, where would I get a "real" replacement? The original HOT installed was a Matsushita 2SD517.

[Findm-Keepm]

For me, in the case of TO-3 Horizontal Outputs WITHOUT integral Damper Diode, I use the RCA bagged or boxed 2SD822. RCA bought them by the bucket loads from Toshiba to offer an OEM HOT - in the 1980s. Don't buy them loose or with a shiny top - all 1980s/original 2SD822 transistors were frosty finish. The bagged ones are best, as you can guarantee no swaps with fakes. BTW, all lot "3A" 2SD822s are fakes. Chinese vendors never switched lot codes, and a 2002 produced fake and a current fake, same lot number.

Of note: the later 2000s "SK Series" (no RCA logo) 2SD822s are suspect. Thomson bought and produced a whole line of supposedly OEM transistors, ICs, STRs, and STKs, but many were counterfeit from the get-go.

If you can't find a RCA packaged 2SD822, then go with the SK3710, ECG238 or GE-38, all of which were produced before the Chinese dumpex.

Nearly all of my replacement were bought 1981-1992, so I know my stock of parts is genuine. I can't say that for some servo amp MOSFETs and Transistors I have to buy for current repairs - it's a minefield. eBay simply ain't the answer - unless it's sealed bags from RCA SK Series, GE's Pro-Line Replacements, or ECG bagged / boxed parts. Replacement guide for each is on the Internet Archive site, so cross reference is at hand, free.

NTE has had a rash of fakes - mostly in their STK replacements, some audio power amp transistors and a bunch of their "commodity" (high demand) parts.

Off topic a bit, but still somewhat germane, beware of Motorola transistors bearing post 1999 date codes. As of August 2000, all Motorola production was spun off to OnSemi, with their logo appearing after that date. ONSemi PCN 10143:
"ON Semiconductor will begin the changeover from the Motorola logo to
the ON Semiconductor logo for packaging materials on May 15, 2000
and for part marking on July 15, 2000. This General Announcement
affects all ON Semiconductor part numbers.
Motorola logos will be removed from bar code labels and will not be
replaced with the ON logo (ON Semi bar code labels will be "plain").
For a period of time, you may receive mixed shipments of ON
Semiconductor and Motorola bar code labels, packaging and parts."

And yet, Dalbani will happily sell you a Motorola transistor bearing a 2004 (0420) date code:
https://www.ebay.com/itm/144102545290

Cheers,

[luRaichu]

I found one lot of open box 2SD822's on eBay for a better price than what I paid for the 2SD517's. https://www.ebay.com/itm/254620362049 Comes in original old stock boxes. Should I cancel the 2SD517's? Will the 2SD822 be a GOOD 2SD517 replacement?

[luRaichu]

The 2SD822 seems slightly weaker than the 2SD517. For instance, the 2SD517's maximum Collector-Emitter Voltage is 700v, whereas 2SD822's is 600v.
However, a 13" CRT is pretty small. The 2SD517 datasheet says it's "Designed for use in large screen color deflection circuits". Did the designers of the CT-1310M use a better rated HOT than necessary?

[ARC Tech-109]

More of what was available in mass quantity for the best price in the day. When I was in broadcast those Panasonic 1310's were a staple in the edit suites and were more forgiving than the Sony to poor sync and other issues but they suffered from cracked solder connections mainly around the CRT socket pins and the row of power resistors in the supply chain. The connections may "look" good but in fact may have a slight hairline crack, this is common with TO-220 devices where the center lead expands more and pushes harder than the others being it's the collector and part of the metal tab, power resistors will dissipate a significant amount of heat through the leads. Any time there is thermal cycling there is going to be mechanical stress and you're dealing with 40-some year old wave soldered connections that were the minimum to make the set work then.
If all is well in the other circuits the counterfeit transistors should work just as well as the original.

[luRaichu]

Originally Posted by ARC Tech-109

More of what was available in mass quantity for the best price in the day. When I was in broadcast those Panasonic 1310's were a staple in the edit suites and were more forgiving than the Sony to poor sync and other issues but they suffered from cracked solder connections mainly around the CRT socket pins and the row of power resistors in the supply chain. The connections may "look" good but in fact may have a slight hairline crack, this is common with TO-220 devices where the center lead expands more and pushes harder than the others being it's the collector and part of the metal tab, power resistors will dissipate a significant amount of heat through the leads. Any time there is thermal cycling there is going to be mechanical stress and you're dealing with 40-some year old wave soldered connections that were the minimum to make the set work then.
If all is well in the other circuits the counterfeit transistors should work just as well as the original.

Never mind, then. I cancelled my order cancellation.

[luRaichu]

Originally Posted by ARC Tech-109

they suffered from cracked solder connections mainly around the CRT socket pins and the row of power resistors in the supply chain.

Row of a what now? "supply chain"? What am I looking for

[luRaichu]

I canceled my order of 2SD517's from ceitron. I'm gonna use 2SD822's instead.

[ARC Tech-109]

Or there abouts, it's never spot on and will vary according to beam current and other factors.

[luRaichu]

What's normal HOT temp? It was warm last run, but that could be heat from the flyback.