Zenith chassis 11A21 mono HiFi help

[DavGoodlin]

I have a model HF1284, 1958 so it barely fits in this category.

[DavGoodlin]

Referring to Sams set 416, which we do not have, I need a scan of the power supply section because the first section of the "Muter"- made, cand-ohm style power resisitor is open.

I am replacing the two 40@450v caps on either side of it and the first section of this multi-tap resistor is open. Normally, I fix the power supply just so I can get a power-up and see what else is wrong. Just the voltage and current on either side at this point could help me "size" a replacement. The 10 wax-paper caps will have to wait until then.

This Zenith console HiFi has a sealed speaker cabiinet and featured in an 2-page advertisement with Les Brown, before stereo!

[damen]

Zenith Sams 416-12

[DavGoodlin]

Thanks Damen!

I had sams 394, showing the HF 1290 series HiFi's but that had a separate amp chassis with P-P 6L6, which is not much like mine as it has 410 V as highest B+

After I replaced the 120 ohm, both 40 uf electros, and powering up at only 70 volts, it still smoked the R60c section, even after I disconnected the 20uf caps.

These resistors are always trouble, this one probably has a fault in the middle section to ground. A high impedance fault as the waxed-cardboard insulator likely tracked. Some DC appears on the other taps, so its NOT a low resistance short.

[DavGoodlin]

I ended up disconnecting that multi-tap power resistor altogether and cobbled a few terminal strips outside this cramped chassis, planning to enclose in perf-metal shield, it fits in the cabinet. I also found a short between plate and screen grid wires pulled too close together on one of the 6V6s, probably caused the initial failure instead of a cap.

A power up today confirmed that after I replaced the four caps in the PS, I need to forget about the radio. Both AM and FM are dead with suspicious crackles indicating IF transformer integral caps have silver mica disease. The stupid compound dial cord is broken in both loops. The amp function sounds pretty good so far, even before the wax-papers get replaced. Most resistors checked higher but within 10%, typical for this age.

All my friend wanted was a good guitar and aux amp, and with record EQ switch, presence control, pair of electrostatic tweeters and pair of 12 inch LF drivers with a 7.5" mid, this promises to be a sweet sounding amp.

Besides, I have two more '57-'58 mono consoles with their original cobra changers, in better shape with the same chassis. Guinea pigs like this one make for easy fixes on these other two

[DavGoodlin]

This link shows the exact model with a later version, 12Z20 chassis. The 6J5 is on a side-car chassis.
http://www.raincityaudio.us/blog/195...console-repair