202-R Arrived

[audmod01]

Today the 202-R that I ordered through eBay arrived. It is a little the worse for travel - most of it is intact, but the AM loop antenna is broken. The actual ferrite bar is broken in two. The plastic material that held it to the moveable steel bracket is also broken. One tuning knob came off of its shaft, but the shaft appears still straight and the knob went back on easily. There is a strange odor - some sort of smoke? about the unit. There is some evidence of roach deposits, but not nearly as bad as the X-101-C I restored. I do not know if the ferrite bar can be glued back together or whether it would affect reception by doing so. Anyone have any experience with gluing an AM loop antenna ferrite bar back together?

The front panel is not bent, just corroded, so I believe much of the corrosion can be taken care of. The dials both move smoothly with pointers moving along to either end OK. Only one cap is missing from one knob the rest are all there. That is fortunate considering this period of Fisher products.

Here are some pictures:


There is the broken AM loop antenna and ferrite.

Joe

 

[dcgillespie]

Joe -- Maybe your best best is to use a small little outboard 1A 6.3Vac transformer mounted with the MPX-65 to power its heaters. I would also suggest converting it to a WX type chassis. The WX uses 12AT7s in the V100 and V102 positions, with the primary reason for the two different versions being that the WX chassis could run off the much lower voltages that tuners employ, which is why this was the sub-chassis used in the tuner units that had a built-in decoder. The MPX-65 on the other hand was designed to operate the input band splitter stage and the matrix output stage from closer to 300 vdc which was readily available within a receiver chassis, so the 65 was the choice for all C version and 400 receivers. It simplified the extra dropping/decoupling stage required when the WX was used in the B version receivers.

Think you'll have this one done by the weekend?

Dave

 

[larryderouin]

The only way I know of to repair the antenna is to find one of similar length and diameter (ferrite bar) and warm up the windings (wax holding it on the bar) and slip off the old one and insert the new bar. Gluing the bar 1/2's together doesn't work, as the ferrite needs to be one length. TA-600, TA-800, 202-T units are similar, and may work in toto. If there is enough of the mount flat part to bridge a piece of breadboard between it and the metal mount, 2 part epoxy works.
http://audiokarma.org/forums/index....gin-ta-600-nudies-inside.534709/#post-6981963 Pics here.
Larry

 

[mrphilco]

Joe

Congratulations! You are going to love that 202-R once you have it up and running again.

Here are the power transformer specs you had asked for in my 202-R thread, courtesy of Howard W. Sams:

Primary - 117V @ 70 mA
HV - 180V @ 200 mA
Fil. #1 - 6.3V @ 1.1A
Fil. #2 - 6.3V @ 4.7A

 

[audmod01]

Dave;

I was thinking about that. You read my mind! I had looked closely at your description of the early tuner versions of the MX sub-chassis with the 12AT7 tubes and I like that approach. It would not be difficult at all to implement. A separate filament transformer would be easy to add as the current demand would be minimal. It could be turned on from a relay slaved to the power from the tuner.

Larry;

Thanks for the info on the ferrite. I suspected as much and you confirmed it. I think the AM ferrite from the 610-T chassis might be the right size. It might even be the correct windings as well. I will check and see.

Ron;

Thanks for that data point. That way I can know whether it could support some extra filament load such as the MX sub-chassis. I will have to add up all the filament currents on each filament string to see what each winding's actual load is.

I started doing some cleaning on the front panel already. Brasso seems to work best so far. The panel is made of stamped brass that is about 1/8" thick. When I get to the areas that have lettering I plan to cover them with tape until I get all the surrounding area and then get into spaces between letters with Brasso and toothpicks to clean and polish those area. So far so good.

I have go get back to my granddaughter's stereo which is the 440-A and 490-T and get that done asap.

Thanks guys! You are great!

Joe

 

[rufleruf]

Neat tuner Joe. I look forward to what your faceplate cleaning efforts achieve. I have a few Fishers with this era of faceplate and most are challenged.

 

[audmod01]

Matt;

Yes even brass cabinet hardware suffers corrosion over time. I have recently worked on my E H Scott 800B by installing it in a cabinet that was originally made for an E H Scott Metropolitan 16A. Its brass door hardware had turned just about black. I managed to remove them, soaked them overnight in vinegar, then used some Turtle chrome polish and brought them back to a nice bright finish. I sprayed them with a light coating of clear lacquer to provide some protection against future corrosion, knowing that eventually they will go dark again. At least for now they look good again.

The escutcheon panel on this tuner had some scratches a couple of spots along the top edge which started some particularly bad corrosion there. However, application of some Brasso using Q-tips has brought back that area. In working with the Q-tips I found that some areas of the panel still have residual lacquer coating, but around the knobs where fingers have rubbed often, the coating is gone and that is where the corrosion is worst. If it turns out that I cannot bring back the panel to my satisfaction, it is possible to get a new panel made, although it would probably be brushed anodized aluminum. There is a thread on this forum that I remember seeing which mentions a contact that can do this for us. I don't remember the details, but the examples that some members have received were considered worthy of the cost and effort.

I took a before picture of the panel yesterday before I started the cleaning and polishing process. After I make some decent progress on it I will post pictures here.

Good luck with your projects!

Joe

 

[audmod01]

Larry;

I checked the 610-T that I have and its AM loop antenna is the same OD and length as the broken one on the 202-R. I need to check further, but I may be able to use it intact, just remount in a manner similar to what was shown in the link you posted. The one on this unit looks exactly like the one in the threat you linked. Even the metal bracket it was mounted on is similar if not identical.

Thanks for that input.

Joe

 

[larryderouin]

Quite welcome. I forgot about the 800c I have that had a broken antenna rod, and replaced it with one from a 700-T. Same dimensions, and turns on the windings. And it worked just fine.

Don't go overboard with the Brasso. This is extreme for forum purposes but the premise is the same(Don't try to get it to USMC standards). The Navy found in the 50's that submarine torpedo tube inner doors were getting daily applications of Brasso(the "Run she May, SHINE she MUST" mentality!!!), and the bronze on the inner doors was actually thinning out in places. Not a good idea, letting water in the people tank!!! So they stopped use of Brasso on Tube doors as it was somewhat abrasive and replaced a bunch of Inner tube doors. The boats slated for early retirement (within 3 years) were depth limited to 250ft with outer doors open, and no new doors.

 

[audmod01]

Larry;

I took pictures of the broken AM loop antenna and sent a copy of it to the seller of the tuner. The box had no evidence of rough handling, but the packing inside the box was a little loose and I think that allowed just enough movement that it broke the plastic bracket and the end of the ferrite rod. I don't know if the seller will allow me some credit against the purchase or not. We shall see.

Yes the Brasso does indeed have an abrasive as does Turtle chrome polish and Weiman's metal polish. I suspect nearly all metal polishes do have an abrasive in them. I don't have any way to prove it, but I think this particular tuner was owned by a lady who wore diamond rings all the time. There are numerous small scratches and nicks around each knob location. The Brasso is doing a fairly decent job of removing or minimizing the scratches at the same time it removes the corrosion. Yeah, it is worthwhile to know when to stop too. One thing about this type of work is that since I have arthritis in my hands and fingers, it tends to encourage me to stop and not overdo the polishing. I think I have a certain amount of OCD though and it often kicks in and I go farther than most people would in such efforts.

Charlie Ramirez sent me the unusual 9-pin plug that fits the Electra IV 440-A amp/power supply chassis, so I will not have to change connectors or make a custom plug now. Thanks Charlie!

Joe

 

[audmod01]

Dave;

No I will not have the unit done by the weekend. That I can guarantee. I just don't move that fast. I am still working on my granddaughter's 490-T/440-A combination stereo system. This 202-R will come later, although I am currently cleaning and polishing the front escutcheon panel. I might go as far as repairing the AM loop antenna arrangement based on using the loop antenna from a Fisher 610-T chassis I have for parts. I checked and it is the same size as the one on this set.

Joe

 

[audmod01]

Here is a before and after initial cleaning of the escutcheon panel. There is considerable corrosion along the top edge in the first picture. In the second, I had cleaned along a good portion of the top and on the upper right section of the panel. I masked off around the word "STEREOPHONIC" at upper right and will work on that area later with toothpicks and Brasso. That will be the most tedious part of cleaning and polishing.



I used Scotch brand magic mending tape to mask off the lettering.

Joe

 

[dcgillespie]

That's amazing, Joe! With your attention to detail, it will look like new when you're finished!

Dave

 

[audmod01]

Dave;

Thanks for the compliment!

I meant to ask, what color is the center jewel supposed to be? Is it amber?

Joe

 

[larryderouin]

That type escutcheon matches that on my MPX-100, which is anodized Aluminium. It won't take a whole lot to go thru the anodize.

Don'cha just love people who don't know how to pack stuff so it don't shake in the box??? It boggle's the mind at times.

 

[audmod01]

One thing that occurred to me is that if I were to change to LED dial lamps, the current load on the filament circuity will drop. I could do the same thing on the indicator lamps behind the jewels. LEDs usually draw way low milliamps compared to incandescent lamps.

Joe

 

[mrphilco]

Joe

Nice job on that front panel! I don't have the patience to do what you are doing, being as careful as you are around the lettering...

All of the lamps in my 202-R have been replaced with LEDs. The lower current draw is bound to be good for the power transformer.

 

[gadget73]

I can offer a +1 on the WX decoder. I have two, and they both work quite nicely. 160 vdc B+ and about a 12K resistor to provide the 125v line and you're good to go. Its under 10ma of plate supply to make one work too. Output to an eye tube is available, but not strictly neccesary if you don't want to add one. An EM84 will light up fine with around 200v on the plate.

The other reason I like the WX is it gives me a place to use some of those 12AT7 tubes I own. It also doesn't need quite so many blasted 12AX7's, of which I never seem to have quite enough. Every piece of gear I own seems to need at least one, some need as many as a half dozen. I have no idea how many I've bought over the years but I never seem to have any extra.

 

[audmod01]

Gadget;

I like the idea of reduced voltage and current in the MPX decoder. Less heat dissipation is always a good idea and subjecting tubes to lower voltages is better than excessively high voltages. High voltages and high current generally lead to quicker failure down the road.

Ron;

Thanks for the compliment. What color is the center jewel on your 202-R?

Joe

 

[audmod01]

Ron;

Ignore that question above. I found the answer by looking in the parts list. The escutcheon panel arrived with one amber and one green jewel in place, so the one remaining (center) has to be an red color jewel according to the parts list. I have one on hand from work on my X-101-C so all I need to do is to install it.

Joe