[BrendaAnnD]

Finally pulling up the first 800B tuner. The biggest thing I see with this is the solenoid seen in the picture below. Aside from the missing coil, I can only see two wires to connect to four connections. There is also one of the plastic cased electrolytics that is broken, but I'm sure I can deal with that.

   

This is the heaviest doggone thing I've ever lifted. I've got complete old receivers that are feather light compared to this tuner chassis alone. I like to have cut my fingers off when this tuner chassis fell on them while trying to manoeuver it to pick it up.

[morzh]

It is in fact very clean. Or it seems to be.

[BrendaAnnD]

Underneath is indeed very clean. Can't say as much for the top. The chrome on top is pretty much toast. I don't see a lot of actual rust, but the chrome has turned to very small flakes.

[jerryhawthorne]

Brenda, looks like that coil did a little smoking. If that solenoid arrangement is for the power switch it would have been simple to just "set" sliding armature to the on and unplug the radio for off. No idea if all four coils are identical but would think so as both solenoids work in the same fashion. Energize one coil and it pulls the armature towards it, rotating the switching wafer to that position where it stays without power. Energize the other coil and it pulls the armature in the opposite directing, rotating the switch back. Really neat mechanism that takes the lateral move of the armature and results in a rotary turn of the switch wafer. Not looking at the schematic but it would seem to me that each coil would have only two terminals for energizing from the low voltage transformer. Can't image why the coil would have 4 connections.
The underside of those chassis do seem to stay very clean but the chrome, particularly on the cans for the AM and FM IFs are very prone to flaking. The chassis, not flaking but rust pits.
As indicated in a previous post you may wish to contact Norman who has helped me with parts. If the "plastic" cap you were referring to was one of the e-caps on the power supply and you have the top cap in good shape, I have a good barrel that I removed to top cap from to put on my chassis that had blown the top cap off some time in the past.
Good luck and build up those muscles, when you get to the power supply, that is even heavier.
Jerry

[BrendaAnnD]

Jerry,

I have the power supply...

What I mean by four connections is that each coil has two terminals, with two coils per solenoid. So, there should be four wires (or, at least three, with one of them going to both coils), but I only see two wires hanging free.

Which Norman are we talking about?

The broken e-cap is on the tuner chassis, you can see the bottom of it just up and a bit to the left of the solenoid.

[Arran]

More crap chrome plating from the "Stradivarius of Radio" those things must be flash chromed like cheap bicycle parts, no copper or nickel plates underneath. The other solenoid coil obvious went to that part's drawer in the sky. If you are lucky you may be able to find out the maker of the solenoid, like Allen Bradley, and be able to find another, or a least a donor for another coil and mount.
Regards
Arran

[jerryhawthorne]

Brenda, attached is a thread started by Norman. He has a vast knowledge on Scotts and has helped my with parts.
Jerry

http://antiqueradios.com/forums/viewtopi...1&t=235022

[BrendaAnnD]

Today, I got to really play with this thing a bit. Not a sign of hum, power supply and amp work like a champ. I figured out that the destroyed solenoid was the power switch.

First thing about the tuner: I got AM right away, even with my variac at 100 volts. Sensitivity very good, but didn't notice a lot of difference between the medium and broad bandwidths, volume is lower on sharp.

FM was a different story. I could get nothing at first. Finally, I found that a) someone had put the tubes in the wrong sockets for the FM tuner and b) one of the three, a 6AG5, was broken near the base. Luckily, I had a couple of 6AG5's I had salvaged from an old PSB transceiver. Putting all three in the proper sockets brought me some functionality, but very little, just one strong station, very weakly.

Much of the problem with the FM after that was with the IF chain, which was badly detuned. A good alignment helped a lot. Still, it's not like it should be. I suspect a great deal of front end misalignment, but I haven't gotten access to that as yet. Also, there seems to be some poor connection, likely the tuner ground, as the tuning changes with any movement of the chassis.

As I was working with the SW alignment, the AM suddenly just quit. B+ dropped out completely, even the regulator tube. Very odd, to say the least. I'll have to try to track that down tomorrow. Note: the FM still works, and all B+ is still there when the set is switched over to FM. I have to do this manually, though, as the pushbuttons also stopped responding at the same time as the AM died.

Wish me luck.

[jerryhawthorne]

Wijshing you luck BAD! You seem to have things under control. At any rate moving forward? Hope you have no problem finding a coil for the on off.
Jerry

[BrendaAnnD]

Back at this beastie this evening. Found the AM problem. It was one section of one of those pretty chrome three section caps. Dead short... pulled the regulated B+ right down to nothing, and didn't smoke the 1K resistor in series with that cap. I replaced the entire can with a terminal strip and three 0.1/630 caps and a 1K resistor. AM/SW are back, and better than ever.

FM is improved a little from before, I can now receive most of the stations on my inhouse cable system, but tuning is still very scratchy, especially on the lower end of the band. Still trying to figure that one out. Only thing I can think of is poor ground connection to the tuner rotor.

Another issue with the FM that I need to figure out is why the 1st IF secondary (which is on the amp chassis) does not tune properly. I have to tune the slug as far in as it will go to get anywhere near the peak. Guess I'll have to pull the can off and see if perhaps something has happened to the coil.

Tomorrow, it's go through and change out all those nice can caps. Wish I could restuff them, but I just have no way of desoldering the bottoms.

[Chuck Schwark]

Maybe the ferrite slug has cracked and there's a piece stuck at the bottom or not moving or a piece crumbled out and you don't have enough slug to tune?

Some shorted turns in the coil? Impregnation integrity compromised and moisture invaded? Copper "greenies" on the coil(s) or at the lugs?

Just typing out loud….

Chuck

[jerryhawthorne]

Brenda, I used a dremmel and cut off wheel to cut the bottom out of those cap cans. Restuff and leave the bottom open.
Jerry

[BrendaAnnD]

Chuck,

Not really sure they're using ferrite slugs in this, but that's one of the things I need to check out. Definitely will check for greenies. This is an interesting FM IF setup. The first IF primary is on the tuner and connected to the 1st IF secondary by a coaxial link. Amp chassis has two stages of IF amplification, followed by two stages of limiting and discriminator.

Jerry,

Thanks! That's a great idea, and I'll give it a shot. May have to buy a bunch of 0.1 disc caps, though, don't think the poly caps I have will fit in the cans.

[jerryhawthorne]

BAD, buy a bunch of cut off wheels, I like the thinner ones as they go quicker. Wear glasses, they will break and fly apart. After a lot of experience doing this I could get about 1.5 caps per wheel. I also cut the tabs coming off the cans as close as I could with a cutter. It left the wires attached to the lug. You will find that the wires give no real extra length for cutting off and then reattaching. Remove the can, cut out the bottom, clean it out. Drill our heat the left over nub on the can. I would heat it and then bang it down into my trash can to knock the solder off. If necessary a little drill on my hand drill to clean it out.
Next, just stuff with the long leads coming out of the hole. Solder the connection to the hole although not necessary. Then take that lead and wrap it around the the wire/stub you cut off and solder.
Really not that hard. Trying to remove those wires from the original connection was, well, a CENSORED. This worked for me and left everything underneath looking neat.
Regards, Jerry

PS: Had no problem stuffing poly caps inside of any of them.

[BrendaAnnD]

More progress.

Forgot to mention I restuffed that plastic 'lytic. It looks for all the world like it grew that way. Wish the metal ones were so easy. Waste of a couple 500V 'lytics, though. It seems that the voltage across them is only about 26 volts.. cathode bypass caps for the 1st and 2nd AF amps.

Found my FM 1st secondary problem. Oddest thing. The 100pf (.0001) cap across the tuned part of the coil was errant. Luckily, I have a bunch of nice 100pf 1KV disc caps, and when I replaced that mica cap, I could actually peak the coil well within the range of the slug.

Also found why all my preset buttons quit working, and it had nothing to do with the other problem. Apparently, the bandwidth switch MUST BE on M(edium) in order for those buttons to work. I found that in the service literature while attempting to look for other things.

Can someone tell me, what IS that control accessible from the top of of the tuner chassis, in front of and to the right of (with the tuner facing you) the tuner? It's totally rusted so I can't just adjust it and see what it does, and there's nothing about it on the pictorials of the chassis'.

I contacted Norman over on the ARF, and he has the on/off solenoid in stock and bought it. Will be nice to not have to manually operate the actuator to turn the set on and off.