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Sadness = Silver Mica Disease (SMD)
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Bullwinkle
- Posts: 338
- Joined: Thu Sep 05, 2019 6:37 pm
Sadness = Silver Mica Disease (SMD)
Honestly guys, I'm pretty proud of myself for going through this. I was just reading about another guy that was very sad to find his two H723's both had this dreaded radio cancer. He junked both of them! Just didn't have the heart or courage to tackle it. He thought all he could do was look for NOS IF cans. No way. But this Zenith design is a great player, super sensitive with a great speaker and audio output stage. Such a shame not to have restored them. It's more than that, it's a crime.
More notes in the caring series: My latest process is to unconnect the coil wires, labeling them of course for later reconnection. Then you can more easily get a first measurement of the caps before disassembling. Maybe the tarnish affects it but then after I remove the wafer, I clean the tarnish and measure the wafer directly. On T3, both ways gave 27pF. I used 30pF's that we had on hand. With the wires off you can more easily manipulate them, cut off the pads, and reassemble without risking the delicate coil wires. It's an easy matter to tack the wires back on after reassembling. I am now the world's expert on SMD. I should become a consultant and charge big bucks!
More notes in the caring series: My latest process is to unconnect the coil wires, labeling them of course for later reconnection. Then you can more easily get a first measurement of the caps before disassembling. Maybe the tarnish affects it but then after I remove the wafer, I clean the tarnish and measure the wafer directly. On T3, both ways gave 27pF. I used 30pF's that we had on hand. With the wires off you can more easily manipulate them, cut off the pads, and reassemble without risking the delicate coil wires. It's an easy matter to tack the wires back on after reassembling. I am now the world's expert on SMD. I should become a consultant and charge big bucks!
Sherman Peabody
Director of Linux Development
Director of Linux Development
Sadness = Silver Mica Disease (SMD)
Why wait? Anyway, school sucks.Maybe finish elementary school first.
Folks, I re-aligned all the rebuilt cans. They all peaked up just fine so that means the cap values are dandy. This really perked up the radio and eliminated distortion on FM. I can get MeTV FM really strong and clear. That's the one we want to play 24-7. No FM radio is finished until it can pull in MeTV FM like a champ. It's sort of a litmus test. Albert taught me about litmus tests.
https://metv.fm/
And just to put the cherry on top, I changed the audio output plate bypass cap from 0.01uF to 0.0022uF. It really improved the highs and now this radio sounds awesome. It was sounding a bit muddy with 0.01uF. I wanted to get rid of that cap completely but people told me you need one in there to protect the audio output transformer from transients. OK, why not?
Claiming victory on the electrical restoration! Moving on to the case. Gonna research bakelite care and feeding before I do anything.
On the Crosley 817, I replaced those big gaudy knobs with some smaller sweet looking repro wood knobs.
Sherman Peabody
Director of Linux Development
Director of Linux Development
Sadness = Silver Mica Disease (SMD)
I'll see that and raise you this:
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Wonder Woman
- Posts: 58
- Joined: Sun Feb 07, 2021 10:46 am
Sadness = Silver Mica Disease (SMD)
Sherman's going to research bakelite. 