An Emerson with a 19AP4??

[Kamakiri]

Man, you're good

Goes to pin 4.

[jr_tech]

Originally Posted by Kamakiri

Goes to pin 4.

Found it! looks like it is R-64 (not used on all models) 30K/5Watt that is shown below the audio output transformer. It makes connection to the +25Volt source *instead* of a direct wire. It appears to me that the resistor and focus coil and the audio output stage form a crude divider network. The focus is actually set by the pot R-2 that varies the current drawn by the audio output tube.... Good Grief!!!

jr

[Kamakiri]

It's almost sounding like they took an engineer who designed some of the 7" electrostats and said "hey, wanna work on a big one?"

Me thinks this set was very much designed to a price point. The only thing that concerns me is the added cap on the v. linearity. I'm reasonably sure I traced out the disconnected caps correctly by the schematic. There's quite a few sloppy solder joints in this set, but I've cleaned them up and traced them out and they appear to be right.

There's even a factory 4 section filter can where only 3 sections of it were used. The 4th is just empty. I've only seen that on really cheap off brands. They must have sold these sets at Woolworth's or something

As I started to do the filter caps, I moved over one of the corroded resistors and a big chunk of the ceramic flaked off. Time to place a Mouser order.

[Kamakiri]

Couple of quick chassis shots.....

[dieseljeep]

Originally Posted by Kamakiri

It's almost sounding like they took an engineer who designed some of the 7" electrostats and said "hey, wanna work on a big one?"

Me thinks this set was very much designed to a price point. The only thing that concerns me is the added cap on the v. linearity. I'm reasonably sure I traced out the disconnected caps correctly by the schematic. There's quite a few sloppy solder joints in this set, but I've cleaned them up and traced them out and they appear to be right.

There's even a factory 4 section filter can where only 3 sections of it were used. The 4th is just empty. I've only seen that on really cheap off brands. They must have sold these sets at Woolworth's or something

As I started to do the filter caps, I moved over one of the corroded resistors and a big chunk of the ceramic flaked off. Time to place a Mouser order.

All Emerson products were built to a price point! They seemed to be "third tier", competing with Olympic, Tele Tone and a lot of the private labels.
The engineer that designed the 7" e-stat, must've been rather sharp, as they were the only one to build a set to run on 110 vdc. All the other's had to have voltage doublers and tripplers.

[Kevin Kuehn]

There's definetely a resemblance to the wiring in my model 698. It's like a monkey pile of wiring, components buried at lower levels.
Not fun to work on.

[jr_tech]

Originally Posted by Kamakiri

The only thing that concerns me is the added cap on the v. linearity. I'm reasonably sure I traced out the disconnected caps correctly by the schematic.

Looking at the picture in my Sams (page 16), it appears that there is a cap connected to the end of R-7... it is standing nearly on end, and identified in the picture on page 9 as C-45. C-45 is shown as a .05/400 volt cap that is connected between the wiper of the brightness control and the minus 185 Volt supply. Since the vertical lin control also connects to the -185 Volt supply, perhaps it is being used as a tie point for the -185 Volt line. If that is true, then it is not clear *why* that point is also tied to R-64 in the focus divider.
I would think that some careful tracing out of the connections related to the -185Volt supply might be necessary at this point in time, as it is not clear that schematic that we are looking at (Sams) represents the wiring observed in the chassis. How does the Sams compare to the factory schematic or Ryders in this area?

jr

[Electronic M]

Both those chassis, especially Tim's, have that 'prototype that has been half re-made a few times' look to them. It is surprising they did not try to clean up the chassis layout before putting them into production.

[Kamakiri]

Everything I've looked at between the Sams and the Emerson schematic has been identical.

With what I've seen and traced out, my only thought at this point is to continue the recapping and hope for the best once done.