RE: Model 89 Cathedral -
skyscraper - 03-24-2014
Hi everyone. I'm please to say, finally, that the 89 has been tamed.
For good, this time.
Gregb and I have been emailing the past week, and his information about the oscillator coil has been invaluable. In the meantime, I accidentally broke the wire for the winding underneath the tickler, I think the secondary, the one that had a touch of 'green disease.' Could have been fixed, but it needs to be rewound sooner or later, so I went ahead and did it. (It's 146 turns of 30awg, clockwise with the bottom on lug 3 and the top on 5) I made every effort to make the coil as close to original as possible, and it looks like it paid off. It's sensitive across the entire dial, and sounds as good as the coffee filtered speaker cone will allow.
Thanks again to everyone, especially recently to gregb, for putting up with me for so long.
Here's a few pictures. First, the new oscillator coil with both outer windings replaced:
[Image:
https://lh5.googleusercontent.com/-L70RVTClOuU/UzCLsgu-DUI/AAAAAAAACMo/X64wKJOredM/s640/DSC_8006.JPG]
And under the chassis. I tried to keep everything as original as possible, and restuffed all the capacitor blocks. Several resistors were replaced, along with a few wires cut from a junked chassis to look appropriate. The speaker wire heatshrink looks bad, but the RadioDaze multi conductor cloth cable is nearly impossible to solder in tight spaces.
[Image:
https://lh3.googleusercontent.com/-Xfhb_Xas0NU/UzCQli4k22I/AAAAAAAACMo/IvtpWhbpbpo/s640/DSC_8008.JPG]
The top. Still needs a good cleaning.
[Image:
https://lh5.googleusercontent.com/-WsNP03vr5JY/UzCQkmeK7NI/AAAAAAAACMo/BS-7Q2zFOFA/s640/DSC_8009.JPG]
RE: Model 89 Cathedral -
morzh - 03-24-2014
I think it looks good. You are not going to get all original look anyway, and then the techs of old did not care about it as much either. Heatshrink is fine.
I like the green magnet wire on the coil, looks almost misterious
Hey, when it all works, you will forget about heatshrink and what not.
Did you also rebuild the tone control unit?
RE: Model 89 Cathedral -
gregb - 03-24-2014
Hey Will
Congrats!!! Fantastic job on the coil it looks great!
Gregb
RE: Model 89 Cathedral -
skyscraper - 03-24-2014
Thanks Morzh! I bought about two miles of 30 a couple years ago for crystal radio projects, so it isn't intentional, but I do like the color.
Yes, the tone control was also recapped.
Thanks also Gregb, I would still be looking for cold solder joints without your help...
Will
RE: Model 89 Cathedral -
gregb - 03-24-2014
What did you end up using for the insulator?
Gregb
RE: Model 89 Cathedral -
skyscraper - 03-24-2014
A strip of plastic packaging from a windshield wiper. I think it qualifies as blister. Followed your instructions for length and width.
RE: Model 89 Cathedral -
gregb - 03-24-2014
Looks like success to me, way to go!
Gregb
RE: Model 89 Cathedral -
NostalgiaRadioTime - 03-24-2014
Fantastic!!! Way to go, Will. I felt bad that, with all of your patience and help, my set started cooperating and working, and you were still struggling with yours. It didn't seem fair.
It feels good to tame a wild beast like this, doesn't it?
I did re-stuff the tone control block on mine, per the schematic, but only after the set was back together in the cabinet did I discover it doesn't change the sound any in either position.
What value caps did you use in yours?
RE: Model 89 Cathedral -
gregb - 03-24-2014
If my memory serves me I used a .01uf cap to ground and a .015uf cap on the switch leg.
Gregb
RE: Model 89 Cathedral -
morzh - 03-24-2014
I use the values from schematics, they are usually shown there.
RE: Model 89 Cathedral -
skyscraper - 03-24-2014
Hi Greg, thanks! No worries at all, it was good to hear that it was possible
I used a .01 and .015uf as per the schematic. I would try to clean the switch contact. Probe around with a multimeter and make sure the bass capacitor isn't always tied to ground (the insulation around the contact may have deteriorated).
Good luck,
Will
RE: Model 89 Cathedral -
NostalgiaRadioTime - 03-24-2014
That's what I used too, Will, and what the schematic calls for.
Thanks for the tip, Morzh. Would've never thought to do that otherwise.
The reason I asked is I read on a different forum of someone with the same problem who used a higher value cap for one of the two to get a more noticeable difference in tone.
Someday if I decide to take it all back apart I'll investigate further. For now, it sounds fine to my ears as is.
RE: Model 89 Cathedral -
skyscraper - 03-24-2014
The higher the capacitance the more high frequencies will be cut out, but if you can't hear anything I highly doubt the cap is being engaged.
RE: Model 89 Cathedral -
NostalgiaRadioTime - 03-24-2014
You're probably right, Will. But after all I've been through with it, I don't feel like tearing it apart again. At least not for a while. Probably a LONG while
RE: Model 89 Cathedral -
skyscraper - 03-26-2014
I forgot on my radio that the bandswitch wasn't working, so I took it out and cleaned the contacts with fine sandpaper. The 'police' band tunes great now, from 1.3-3.2 mhz.
I think the tone control contact is similar, you could probably loosen it enough to twist it around, and rub the contacts down. Do you have any deoxit?