View Full Version : PVM-1270 HV shutdown HVR mod


colorfixer
10-18-2015, 03:07 PM
I've got a couple of these that suffer HV shutdown with no other visible issues. I'm aware that this is likely an issue with a bad HVR, and that the quick and dirty fix since the HVR is probably unobtanium is to cut the "white wire".

Given that this set is a little more complex than the average 12" TV, I was wondering if anyone has done this "mod" on one of their '1270/1271s and if it was successful (ie the lead isn't used for HV regulation).

The other idea would be to try to make up a new HVR that we could apply to pretty much any Sony that needed one. Has anyone ever had one apart to see where it fails?

As always, any feedback is appreciated.

Zenith26kc20
10-19-2015, 01:27 PM
Have you contacted Curt Palme? I have a 1251 and when it has a problem he is the repair person.

zeno
10-19-2015, 06:47 PM
Most common problem with random shut down was
the H-Stat control assy. Mostly they are arcing. If it has
one wire going to a connector with a jumper cutting
the wire will work but it will arc sooner or later. Look it
over real close, usually will find cracks on it.

73 Zeno:smoke:

rca2000
10-19-2015, 09:18 PM
By "HVR"'do you mean the H-stat" block?

colorfixer
10-22-2015, 02:44 AM
Yes, the HVR block = "High Voltage Resistor"

I looked it over for signs of cracking or burning and the red epoxy potting in the clear body looks good. The HV setup in the manual is quite convoluted. It must be arcing inside?

colorfixer
10-23-2015, 02:42 AM
Good news and bad news.... The HVR "mod" did not stop the HV from shutting down, when it wants to shut down, something else is killing the horizontal output and she loses the high voltage, filament supply but...the audio is still up. Back to the drawing board.

kf4rca
12-05-2015, 11:18 AM
I'd check your PS voltages to make sure they're correct. Might have a shorted regulator.
I have a PVM 1211 and have not had this problem.

zeno
12-05-2015, 07:37 PM
I have worked on quite a few PVM series sets. I
never had one with shut-down. On consumer level
KV**** sets the H-Stat was usually the problem.
Removing the plug & putting a jumper on was a test.
At that point they often arced.....
The wire feeds a latch circuit with 2 or 3 transistors
that kills Hoz drive. IIRC its only for SD. It detects
DC & if over a certain level activates SD.
Also regulator IC or transistor was common BUT the PVM
probably uses a switching power supply ( SMPS ) instead
of the simple pass circuit. Been to long so cant remember.

For now try running the set on apx 100 VAC & see if it
still shuts down. Its at the point where you gotta nail down
if its :
Failed SD circuit
Failed PS
Failed horz osc/drive/out etc.

If you have a manual post the PS & the SD parts, that will
help.

73 Zeno:smoke:

colorfixer
12-06-2015, 06:33 AM
Zeno, here's the entire manual. I figured I'd post this link from another site:

https://www.dropbox.com/s/on6oqbn704dmt1l/sony_pvm1271q%20Service.pdf?dl=0

Thanks for the help thus far. I'll run it up on a variac @100V to see what happens.

colorfixer
10-15-2016, 01:57 PM
Update: apparently the CRT socket is arcing, which it the cause of the shutdown. Any ideas where these can still be had?