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Old 16th May 2005, 10:37 PM   #1
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Default Zenith Amplifier

Hi, last night after some dinner with friends i found an old Zenith Radio someone was throwing out. It had two pairs of speakers: a Cone tweeter and 12" woofer on each side, along with an am/fm radio and record player, and amplifier. I took out the amplifier in hopes of fixing it up to get some nice tube sound out of my speakers. The model number is SFF2535, does anybody have a schematic (or know where to find one?) There are a few obvious problems to be dealt with, the first being the filter condenser (which has a lead broken off) that needs to be replaced with a new one, and then figuring out what tubes are needed for the amp. The previous owner smashed the glass on the old tubes for some odd reason One of the tubes has a base, so it is easy to see that it is a 5Au4 (Rectifier?) There are two other tubes needed for this amp, and i have a broken one, but can't tell what it is supposed to be. The only thing i know is that it has 9 pins, and no base. Help!?

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Old 16th May 2005, 11:26 PM   #2
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Old 17th May 2005, 12:45 AM   #3
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Not listed in Sams index...

SF2535 (tuner only...) and SF2530 schematics are online here: http://techpreservation.dyndns.org/s...ics/Zenith.htm

You'll need to download the DjVu plug-in from Lizardtech.com to view or print them. Tubes in 2530 amp are 5U4 and a pair of 6BQ5s. Will need several volts of drive - not much good without a preamp.
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Old 17th May 2005, 11:38 PM   #4
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Default schematic

Thanks! The SF2530 seems to be the right one. Will it be possible to completely separate the amp from the other parts? If you look at the schematic, the portion i have is the bottom right where it has the 5U4GB Rectifier, the 6BQ5 Power Amp, and 3B32 Power Supply (chassis 3B32 if you are looking at the alignment page. The 9 pin and 7 pin plugs concern me somewhat, b/c they seem to be passing voltage to other boards. Is there some way to safely disconnect that? There are also some slight differences b/c this is actually the SFF2535. For instance, the shielded cable doesn't come into the amp from the 7 pin connector, it comes in by the main transformer (and isn't directly connected to the 7 pin connector).
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Old 18th May 2005, 12:18 AM   #5
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Default specs

any ideas on what the specs might be on this?
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