You should only have a 470K resistor going to B+. Some radios do have a second resistor but also a cap from this point to B-. The extra resistor won't make much difference in your radio.
The 500pf cap isn't needed. Someone may have been trying to add negative feedback? There is a C24, 500pf on the 6S8GT plate. Could someone have connected it to the wrong plate?
It's ok to have the .02 mf across your output transformer instead on one side to ground. The only thing in this radio it goes to C26 which has a 10 meg resistor back to the previous stage. This gives some negative feedback. You radio bypasses this part of the circuit.
http://www.nostalgiaair.org/PagesByModel/426/M0025426.pdf
Norm
:Hi All!
: I'm still working on the Zenith 8H034, I have a question that hopfully someone can answer. On the print it shows R17 as a 470K, connected between the 6S8 and 25L6, what is actually in here are two resistors in series, a 470K & 100K, also I have what appears too be a 500 mmF connected too the Blue lead on the speaker transformer primary side and is disconnected on the other side, so I have now way of telling where the other side goes, and the print does not even show this capacitor anywhere, once more the capacitor appears too be an original rectangular type, so this does not add up, finally the print shows a .02uf from the Blue wire of the speaker primary too a .2uf and ground, well the .02uf is connected too the Blue wire, however the other side is connected too R20 and the Red wire of the speaker primary. one last note R 16 is shown as a 10 Meg and as far as I can tell it is a 2.2 Meg in this chassis, looks too me like changes Zenith made, and the print does not show it, so I have one heck of a delima! without knowing the whys,therfores or therofs, I cannot go any further with this restoration until I get some info to clear this up, can anyone help?
: Mark
:
Changes are not a problem as long as your radio doesn't go into oscillation. It originally had negative feedback. This would have reduced gain.
Norm
:::Hi Mark
:::
::: You should only have a 470K resistor going to B+. Some radios do have a second resistor but also a cap from this point to B-. The extra resistor won't make much difference in your radio.
:::
:::The 500pf cap isn't needed. Someone may have been trying to add negative feedback? There is a C24, 500pf on the 6S8GT plate. Could someone have connected it to the wrong plate?
:::
:::It's ok to have the .02 mf across your output transformer instead on one side to ground. The only thing in this radio it goes to C26 which has a 10 meg resistor back to the previous stage. This gives some negative feedback. You radio bypasses this part of the circuit.
:::
:::
:::http://www.nostalgiaair.org/PagesByModel/426/M0025426.pdf
:::
:::Norm
:::
:::
:::
:::
:::
:::
:::
::::Hi All!
:::: I'm still working on the Zenith 8H034, I have a question that hopfully someone can answer. On the print it shows R17 as a 470K, connected between the 6S8 and 25L6, what is actually in here are two resistors in series, a 470K & 100K, also I have what appears too be a 500 mmF connected too the Blue lead on the speaker transformer primary side and is disconnected on the other side, so I have now way of telling where the other side goes, and the print does not even show this capacitor anywhere, once more the capacitor appears too be an original rectangular type, so this does not add up, finally the print shows a .02uf from the Blue wire of the speaker primary too a .2uf and ground, well the .02uf is connected too the Blue wire, however the other side is connected too R20 and the Red wire of the speaker primary. one last note R 16 is shown as a 10 Meg and as far as I can tell it is a 2.2 Meg in this chassis, looks too me like changes Zenith made, and the print does not show it, so I have one heck of a delima! without knowing the whys,therfores or therofs, I cannot go any further with this restoration until I get some info to clear this up, can anyone help?
:::: Mark
::::Hi Norm
:: Ok, I understand that, however the 10 Meg is not a 10 Meg its a 2.2 Meg in my radio and it is going directly to chassis/ground instead of going too the .02uf and the .2uf too chassis/ground, it looks too me like someone clipped out the .2uf too ground and connected the .02uf across the primary of the speaker transformer, is this going too be a problem?
::Mark
::Also, Norm, it appears that the .2uf too ground was connected too the junction of the 470K & 100K and chassis/ground, which if I'm looking at it right the feedback path would have been through the .2uf & 2.2 Meg too the Plate of the 6S8 through the 470K and through the 100K too the Screen Grid of the 25L6, is this correct? or am I looking at this wrong, if this is so then exactly what would this accomplish? the way I see it, it wouldn't be a negative feed back it would be a regenerative feedback?
:Mark
:
Be sure that the 500 pF rectangular condenser is in fact a condenser and not a resistor. Zenith often used Micamold wire wound resistors that look just like condensers.
Thomas