Ok...it's time to start a thread to document my 47-1230 restoration and ask some questions. This set belonged to my grandparents.
I repaired it in 1972 when I was 17 years old but then it has pretty much just sat and no longer works. I decided that this was a fairly complex restoration for my first attempt so I decided to start with a GE LC-628 I had laying around. I've completed the electrical/mechanical restoration and the radio works! https://drive.google.com/open?id=0B2i1fb...WtFVFRBR0k
Now I'm working on the cabinet which will take me some time so I've decided to come back to the 47-1230 chassis and do some work on it at the same time. I've taken tons of pictures and identified all the caps and obtained new replacements. I've cleaned out the bakelite caps:
So here's my first question...yesterday I removed the pushbutton assembly and it's filthy. What's the best way to clean this up?
I would use cotton swab, dip it in 91% or stronger (no water) isopropanol, clean the board and the switches, and then try one coil to see if it does not dissolve what it souldn't, and then if it is OK, proceed with it. No soaking, just wiping with alcohol-wetted swabs.
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
Also, be careful around the phono switch and push rod on the left. That switchconnection will be very delicate and if it was used a lot, may be worn and bend easily.
Thanks for the input morzh, shaler78, and Warren. I took morzh's advice and tried with some alcohol. I don't have any 91%...I used 70%. You can see a huge improvement already:
I know what you mean Warren...some of those wires are VERY thin. At first I thought this one was some lint or something...glad I didn't try too hard to remove it! Old eyes suck!
I intend to clean everything once, then take it out to the garage and gently blow it out with some compressed air, then do everything again.
Can I spray contact cleaner on the switch contacts as long as I'm careful where I'm spraying?
I think I'm going to call the pushbutton assembly good for now. It's not as clean as I'd like it to be but it's far better than it was. I figure the more I mess with it the more likely it is that I'll cause some sort of damage that would be difficult or impossible to correct.
Actually, there's already some damage. I don't think I caused it but it's possible. The two wires marked in the following image were loose on the ends of the inductors. I touched them with a little solder and they now seem attached, but still don't look right.
I have some questions for Warren since he's done one of these, but all input is welcome. Warren - did you remove the tuner sub-chassis?
It seems like it would be easier to work on the caps in there with it removed. Plus, I want to replace the mounting grommets. I've identified and documented 13 wires and a capacitor that would need to be disconnected. I figured I could wrap some tape around the main dial cord pulley so I don't have to rewind that. It looks like it has an e-clip holding it in. I could take that out and store it with the rest of the dial cord assembly until it's needed.
I know I had another question for you but can't think of it now. It'll come to me and I'll make another post.
Yes, I did remove it only because mine was in such bad shape from it going through a house fire that I replaced it with another assembly I took from a "donor" chassis. I marked every wire to make sure they went back correctly. There are a few caps in that area that is pretty difficult to remove and replace. It is tight in the tuner section. The dial cord isn't to bad to restring, I would take a couple pictures before you take it apart though.
Ok...today I marked all the wires connecting the tuner sub-chassis to the main chassis and removed it, along with the dial backing plate and dial cord.
I also started the process of restuffing the canned electrolytics. I'm going to start a separate thread to document that because I took a lot of pictures along the way, including how to remove the remains once you have it open.
Warren - Did you replace the rubber grommets mounting the tuner sub-chassis to the main chassis as well as the ones for mounting the pushbutton assembly? If so, where did you get them? I've seen some that may be close enough here http://www.renovatedradios.com/parts.html#rubber but haven't seen anything that's exact.
Hi Rich, No, I did not replace mine they were in decent condition so left them alone. If they are not falling apart and still semi pliable I would not replace them myself. I you can compress them and they go back in shape they are probably good. If you want to replace I have heard you can find "O" rings sometimes at home depot that are close enough. Also, if you cant find any you think is close enough I might have some on the donor chassis I have but of course those would be older used ones too. But if yours are falling apart these are probably in better condition.
(03-23-2017, 01:54 PM)Warren Wrote: Hi Rich, No, I did not replace mine they were in decent condition so left them alone. If they are not falling apart and still semi pliable I would not replace them myself. I you can compress them and they go back in shape they are probably good. If you want to replace I have heard you can find "O" rings sometimes at home depot that are close enough. Also, if you cant find any you think is close enough I might have some on the donor chassis I have but of course those would be older used ones too. But if yours are falling apart these are probably in better condition.
Thanks Warren - my tuner chassis grommets aren't too bad and I might re-use them. A couple of the ones for the pushbutton assembly aren't too good but I think there is one at renovatedradios.com that's real close so might try that.
Today I started cap replacement. This is going to be a tedious process since everything is so intertwined and in many places there are many connections on one terminal. I like to clean things up as I go so wherever I can I remove everything from a terminal, clean it up, and then re-attach everything.
I didn't get too far today before I decided to stop and place an order. I checked several resistors as I disconnected them and most are out of tolerance, such as a 150k that measures 211k and a 330k that measures 404k. So I decided to order every resistor I might need. Overkill? Probably. But Digi-Key is always quick and reasonable...$10.63 for every resistor on the parts list, including 2 270ohm 3W resistors to replace the 135ohm 5W that I damaged when I was trying to remove the can caps. This also includes one extra of every value. So at least I'll have everything on hand if I need to replace a resistor.
I'm also considering replacing the shielded cable that runs from pin 3 of the 7X7 tube to the .006uF cap attached to the wiper on the volume control. I suspect this is just plain old shielded cable, right? Or does it need to be some specific impedance?
I'm making good progress with the cap replacement.
Actually, I should call it cap/resistor replacement. It looks like I will end up replacing all but one resistor on the main chassis. There is one attached to the volume control that would be a little tricky to get to and it measures in tolerance so I'll probably leave it. On the tuner sub-chassis I'll probably leave them alone unless I come across one that's out of tolerance and relatively easy to get to.
Now I'm going to have to decide what to do about a power transformer. The one I put in 45 years ago doesn't have a secondary for the heater circuit, plus I think it may be shot. I haven't hooked it up to the variac and tested it yet but one of the windings reads a dead short. So I'm looking for a Philco 32-8248 or a Stancor P-4080. http://www.oldradioparts.com/ lists both, but both have been sold...the Stancor sold a week before I inquired
Warren - I got your reply to my PM but just saw it today. Not sure why. I checked several times for a couple of days after I sent it and didn't see a reply from you. Then didn't check for a couple of days until today. Sorry about the delay, and thanks for checking into it!
Rich
(This post was last modified: 03-30-2017, 11:53 AM by criageek.
Edit Reason: Spelling error
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Shielded cables in this particular case do not have to be of particular impedance.
Impedance only matters when your transmission length becomes comparable or especially when it exceeds the wavelength at which point it is considered a resistor equal to the characteristic impedance as seen by the source; otherwise your cable acts as lumped capacitance/inductance as seen by the source, and your shield is there exactly for that - to provide shielding.
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
Rich, be careful about replacing caps in the tuning front end chassis. There are many caps there that should be left alone, including the precision micas in the tuned circuits.
The only caps to change there are the waxed paper bypass caps.
(03-30-2017, 12:00 PM)morzh Wrote: Shielded cables in this particular case do not have to be of particular impedance.
Impedance only matters when your transmission length becomes comparable or especially when it exceeds the wavelength at which point it is considered a resistor equal to the characteristic impedance as seen by the source; otherwise your cable acts as lumped capacitance/inductance as seen by the source, and your shield is there exactly for that - to provide shielding.
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