#1
|
|||
|
|||
Zenith 7H822Z troubles
I received a Zenith 7H822Z (the "Z" indicates tone control) from ebay a while ago. It was recapped with molded black sprague caps instead of the paper zenith ones, but I replaced all of the caps. This set is an AC/DC set, and used a 22 ohm 3W ballast resistor to limit current flowing through it's stinky selenium rectifier. I replaced the recifier with a 1N4007 and the ballast resistor with a 100 ohm resistor which I had on hand. This may be part of the problem. Anyway, I replaced all of the black sprague and remaining zenith paper caps, as well as the electrolytics. I replaced the "micamold" 100pF line antenna coupling cap with a brand new silver mica. Since this was an AC/DC set, one of the tube filaments was burned out, which was it's 12AU6, so I put a new one in.
So after all this, I powered it up and all I get is buzzing and some low level static, but it's constant static. I'm almost sure it's a wiring issue, or could be the ballast resistor, or both, or some bad tubes. The power supply filter resistor is a 1k, right now 3W was replaced for no reason, but I'm going to get a proper 5W resistor the Sams says it requires. A picture of the chassis underside is here. More tinkering is required, but I was wondering if anything sticks out that I missed. I hear that this radio has excellent FM fidelity, and I'm quite eager to hear it. Thanks again. Jonathan P.S. If anyone has the official Zenith servicing info on this set or the 7H822, please let me know as the Sams has some errata and that might have lead to a miswiring. I'll pay you to photocopy it and mail it to me. Thanks. Last edited by Jonathan; 10-31-2005 at 01:18 AM. |
|
|