CurtPalme.com Home Theater Forum

**AnalogRocks**

My Sony 1252 has somewhere between 14000 to 24000 hours on it.

It's a late model chassis ( silver serial number label, January 1996 ) has 07MSP tubes in it and the G2 voltage is 1.5 volts.

Now I scored a set of nice low hour 07MP tubes last year from some one here ( thanks )

As I understand it the set's that took 07MP tubes needed a G2 of 4 volts.

Can this tube swap be done?

07MSP ---> 07MP?

1031 · Joined: 22 Mar 2006 Posts: 657 Location: Finland

Actually those late model 1272&1252 had little differences made at video amps (those cards where are those VPH-06 ic´s)
If i remember correct there was some resistors changed to different values and due that G2 procedure was changet also. So i thing you should adjust G-2 same as now.

r.bauer · Joined: 08 Apr 2006 Posts: 280 Location: The Netherlands

You probably have not enough range on the focus contol, as the tubes have different focus voltage ranges. While the ranges do overlap, the overlap is not enough.

**AnalogRocks** · Posted: Mon Feb 09, 2009 5:06 pm Post subject:

Hmmm I may need another chassis then. What manufacturing date(s) did the 1252's use 07MP's?

speedyandre · Joined: 18 Dec 2006 Posts: 291 Location: Netherlands

I wonder if the 07mp's ever were in the 1252 Rolling Eyes

The other way, 07msp in a 1270, 1251 or 1271 seems to be no problem (I got it focussed well).
Finding a 1271 with fried tubes gives you more bandwidth and 21 zones.

André

1031 · Joined: 22 Mar 2006 Posts: 657 Location: Finland

**AnalogRocks** · Posted: Mon Feb 09, 2009 6:57 pm Post subject:

ecrabb · Posted: Mon Feb 09, 2009 10:02 pm Post subject:

Jeremy,

I posed this question 3 or 4 years ago, and Curt told me to try it. He warned me about the focus issue, but told me to give it a whirl, anyway. I wanted to learn how to do it and I didn't have much to lose, so I went ahead.

I took a set of Windows desktop-burnt 07msp's out of a 1252 and replaced them a set of the older 07mp's I bought on fleabay. They were perfect, other than having a very light - almost unnoticeable - text burn of some kind on them. Everything worked perfectly, save for one thing: I did have a focus issue on the red tube.

The red just wouldn't focus 100%. I don't think it was a range issue because as I twisted the focus pot, it went from really bad, to better but still not good, to really bad again. In other words, it wasn't like if I could just turn the pot a little further one way or the other it would have been focused... So, since the tubes were used, and the red and green focused completely normally just like an 07msp would, I assumed the problem with the red was probably the tube itself, and not a focus voltage range issue. For all I know, it could have had a kagillion hours on it. The blue and green could have been replaced two times, and the red could have had 20,000 hours on it. Who knows?

FYI.

SC

**AnalogRocks** · Posted: Mon Feb 09, 2009 10:10 pm Post subject: