Author Topic: New Resto Project- 1961 Imperial Magnavox  (Read 9882 times)

Motorola Minion

  • Hero Member
  • *****
  • Posts: 1124
  • Southern Pennsylvania
    • View Profile
Re: New Resto Project- 1961 Imperial Magnavox
« Reply #45 on: October 25, 2019, 09:33:57 AM »
If I was up your way, I'd welcome your amp on my bench. Motorola and Zenith used way too many wires and connectors in various models, and TOTL Magnavox are a similar deal.

The electronics design is solid USA bulletproof. It must be simple like a misplaced RCA-connector patch.

So do I recall yours has a wiring diagram or photos of connections before taken out of the cabinet for repairs?
Tubes - Magical - Tubes

Dave

AC207

  • Jr. Member
  • **
  • Posts: 92
  • 207-450-7299
    • View Profile
Re: New Resto Project- 1961 Imperial Magnavox
« Reply #46 on: October 25, 2019, 10:57:46 PM »
If I was up your way, I'd welcome your amp on my bench. Motorola and Zenith used way too many wires and connectors in various models, and TOTL Magnavox are a similar deal.

The electronics design is solid USA bulletproof. It must be simple like a misplaced RCA-connector patch.

So do I recall yours has a wiring diagram or photos of connections before taken out of the cabinet for repairs?

Hi Dave- That's correct. I did photograph everything before removing but I also have the schematic (from here).  While I think I have everything connected properly, it's quite possible I don't.

In a nutshell, we've replaced all of the electrolytic caps in the amp. So far I haven't touched the tuner or multiplex unit.  Unit powers up... no smoke and everything that lights should light.

I've tried connecting my phone directly to RCA inputs on amp with everything plugged in (again, hopefully correctly) and still get no noise.... no static... no nothing. 
An honest man's pillow is his peace of mind.

Motorola Minion

  • Hero Member
  • *****
  • Posts: 1124
  • Southern Pennsylvania
    • View Profile
Re: New Resto Project- 1961 Imperial Magnavox
« Reply #47 on: November 02, 2019, 08:43:22 PM »
You may need to start at the speakers and verify everything is connected simpatico, meaning where it needs to be. Speaker wires are simple until you get to the external speaker switch, then very little makes sense unles you designed it -LOL Tube voltages on 6V6 output tubes tell alot.

Right now Im working on just RCA and have not yet worked on a  Magnavox as grand as yours, just an AMP 175 that was barely touched before I recapped and checked every resistor, including transformer winding resistance. Magnavox tube amps have the same issues as RCA most times, and it comes down to old parts that were cheap when new.

Start checking voltages on both sides of the power supply resistors, like that 10 watt power resistor
Tubes - Magical - Tubes

Dave

electra225

  • Hero Member
  • *****
  • Posts: 3583
    • View Profile
Re: New Resto Project- 1961 Imperial Magnavox
« Reply #48 on: November 06, 2019, 02:20:47 PM »
Get out the schematic.  Start at the cathode of the rectifier.  Confirm correct B+.  Then verify the filter caps are wired correctly.  Verify voltage on the filter caps positive.  Then go to the output tube plates, then the screens, and down the line.  If you have B+, then make sure everything is wired right.  There should be a wiring diagram pasted somewhere in the cabinet.  Probably on the rear apron of the cabinet, above the speaker enclosures.  Take it a step at a time and keep us posted.  Another thing.  Do you have the Molex connector from the amp to tuner connected properly, everything seated well.  Did any of the connectors pop out when you connected the Molex connector?
I don't need Google.  My wife says she knows everything.

voxACthirtee

  • Full Member
  • ***
  • Posts: 170
    • View Profile
Re: New Resto Project- 1961 Imperial Magnavox
« Reply #49 on: November 06, 2019, 07:09:48 PM »
I've read this post over time, but don't want to reread the whole thing again, so i'll offer this.....Did it once work ok?? While you can go through the amp testing voltages, most times an incorrectly repaired  amp still will emit some sort of noise, hiss, hum if you stick your ear near the speaker. Thats of course if it doesn't catch on fire or pop a fuse.
Are all the tubes lit up? If so, then definitely do as mentioned a couple replies ago and make sure the speaker selector switch is 1) On the internal setting, 2) Functional.
You can test for continuity on the positives through the switch going amp to speaker.You have to pull the connector and look at the schematic to see which pin is which.
The grounds are common(per side?) so you will get continuity either way if memory serves, but you can verify continuity through the selector switch to the positives to each woofer and each horn.Personally i wire each speaker directly, i don't trust the reliability or the fidelity of 60 year old switches like that. So i can't use external speakers?...i don't have any biamped external speakers.

electra225

  • Hero Member
  • *****
  • Posts: 3583
    • View Profile
Re: New Resto Project- 1961 Imperial Magnavox
« Reply #50 on: November 06, 2019, 07:28:38 PM »
I use an old, cheap set of stereo speakers connected for use with a bi-amp.  I use it with the Concert Grand.  Just connect the positive from the treble amp to the midrange and tweeters, the positive from the bass amp to the woofer and connect the commons together.  I disconnected the crossover network.
I don't need Google.  My wife says she knows everything.