I've pulled the amp out of a Zenith console. The amp chassis has the number 091301 and there's a paper sticker on the chassis with the number: 7H30.
I've searched this site for the schematic, but have been unable to find it. I really need the schematic because the feedback circuit of the amp loops through the console's pre-amp (which is long gone). The feedback circuit was run through a variable R/C network through a "presence" control on the pre-amp. I have no idea how to complete the now open feedback circuit and can't use the amp until I have the right resistor and capacitor values.
Does anybody have the schematic? Thanks a whole bunch!
Greg
I didn't have the presence of mind to note the console model number when I pulled the amp out. This was my first console pull & next time I'll surely make a note of that number. This is what I've found out about the amp:
It’s a push-pull 6BQ5, EL84, Cathodyne split, cathode biased, non-UL amp with 430 volts on the plates and 15 volts on the cathodes. The tubes required are 4 X 6BQ5 / EL84s, 2 X 6FQ7s and 1 X 5U4 rectifier. The power transformer's specs are: 680 VCT @ 240 mA, 6.3 VCT @ 6 A and 5 V @ 3 A. The output transformers measured ratio of 31:1, or about 8K CT to 8 Ohms. There is also a feedback winding (enameled of about 80 Ohms impedance. EIA code "1386131" says these were made by Stancor in 1961. Zenith part number 95-1913.
Sorry... that's about all I know about this amp.
If I can't get the feedback circuit figured out, I'll probably sell it on eBay for parts :(
Thanks for any advice you can offer!
Greg
--------------------------------------------
Well don't throw it to ebay just yet. We, or someone here maybe able to figure out a feedback circuit that will work. If you do want to toss it, i'd tkae it, i've been reading up lately on how to build amplifiers, specificaly with EL84's. At luch i'll do some more searching, to see if a schematic can be found, any model #'s and would help, i didn't find anything with 7H30.
Jeremy
You may be able to find that folder at your library, or you can purchase a copy from the Sams Photofact website (somewhat pricey). Try a google search, someone may have it posted on their website.
Meade
::Hi Mark...
::
::I didn't have the presence of mind to note the console model number when I pulled the amp out. This was my first console pull & next time I'll surely make a note of that number. This is what I've found out about the amp:
::
::It’s a push-pull 6BQ5, EL84, Cathodyne split, cathode biased, non-UL amp with 430 volts on the plates and 15 volts on the cathodes. The tubes required are 4 X 6BQ5 / EL84s, 2 X 6FQ7s and 1 X 5U4 rectifier. The power transformer's specs are: 680 VCT @ 240 mA, 6.3 VCT @ 6 A and 5 V @ 3 A. The output transformers measured ratio of 31:1, or about 8K CT to 8 Ohms. There is also a feedback winding (enameled of about 80 Ohms impedance. EIA code "1386131" says these were made by Stancor in 1961. Zenith part number 95-1913.
::
::Sorry... that's about all I know about this amp.
::
::If I can't get the feedback circuit figured out, I'll probably sell it on eBay for parts :(
::
::Thanks for any advice you can offer!
::
::Greg
::
:
:--------------------------------------------
:Well don't throw it to ebay just yet. We, or someone here maybe able to figure out a feedback circuit that will work. If you do want to toss it, i'd tkae it, i've been reading up lately on how to build amplifiers, specificaly with EL84's. At luch i'll do some more searching, to see if a schematic can be found, any model #'s and would help, i didn't find anything with 7H30.
:
:Jeremy
:According to the Sams index, Zenith 7H30 is covered in Photofact 607-12, published in 1962.
:
:You may be able to find that folder at your library, or you can purchase a copy from the Sams Photofact website (somewhat pricey). Try a google search, someone may have it posted on their website.
:
:Meade
:
:
:
:
:
:::Hi Mark...
:::
:::I didn't have the presence of mind to note the console model number when I pulled the amp out. This was my first console pull & next time I'll surely make a note of that number. This is what I've found out about the amp:
:::
:::It’s a push-pull 6BQ5, EL84, Cathodyne split, cathode biased, non-UL amp with 430 volts on the plates and 15 volts on the cathodes. The tubes required are 4 X 6BQ5 / EL84s, 2 X 6FQ7s and 1 X 5U4 rectifier. The power transformer's specs are: 680 VCT @ 240 mA, 6.3 VCT @ 6 A and 5 V @ 3 A. The output transformers measured ratio of 31:1, or about 8K CT to 8 Ohms. There is also a feedback winding (enameled of about 80 Ohms impedance. EIA code "1386131" says these were made by Stancor in 1961. Zenith part number 95-1913.
:::
:::Sorry... that's about all I know about this amp.
:::
:::If I can't get the feedback circuit figured out, I'll probably sell it on eBay for parts :(
:::
:::Thanks for any advice you can offer!
:::
:::Greg
:::
::
::--------------------------------------------
::Well don't throw it to ebay just yet. We, or someone here maybe able to figure out a feedback circuit that will work. If you do want to toss it, i'd tkae it, i've been reading up lately on how to build amplifiers, specificaly with EL84's. At luch i'll do some more searching, to see if a schematic can be found, any model #'s and would help, i didn't find anything with 7H30.
::
::Jeremy
Greg
If your weather was anything like ours...you couldn't even get there.
Sooooooo here is a cached info thumbnail of the particular info of interest in the "missing unit"
portion.
Pit that you didn't get the other unit with its reverb
"sprangs" ...echo unit.....that unit really was nice sounding when in its complete condition.
The info is J-pegged so that you can zoom on in, should you want to replicate particular circuitry .
http://img257.imageshack.us/img257/4691/zenithaudiosourcingbz9.jpg
73's de Edd
Thanks again!
Greg