X-202-B Acquired

[audmod01]

Dave;

Thanks for those comments! Yes, in the beginning of stereo reproduction, many people dealt with dis-similar speakers and there were issues of speaker phasing or even received signal phase from AM-FM simulcasts etc. coming directly from a tuner or receiver depending on what was done at the broadcast studio and transmitter equipment. We are fortunate that many of these issues have disappeared in more recent times. However, customers may still have dis-similar speakers or custom speakers in which a driver may have its phase reversed compared to its equivalent driver in the other channel. For best stereo effect careful attention to those issues has to be exercised.

Yesterday after some repairs to our water well (pressure tank jet pump replacement), I began cleaning the knobs from this amplifier. Three of the knobs had brass caps and the rest were missing. Of the three with caps, one turned out to be distorted (bent) after polishing with metal polish. I removed all three brass caps and cleaned the tops of the associated knobs to remove all traces of old glue. It turned out that the one brass cap that was bent had been re-glued by someone who did not bother to remove all the old glue residue. There was still some present on the back side of the brass cap and in the grooves of the top surface of the mating knob. They apparently forced the brass cap back onto the top of the knob with some new glue of a different type and this resulted in the cap being permanently damaged. I took one of my jeweler's screwdrivers that had a chisel tip just wide enough to fit into the grooves on top of all the mating knob surfaces. I removed all traces of glue that I could manage. The small screwdrivers do an excellent job of removing all the old glue. Be careful when cleaning the outermost groove which is right next to the fluted outer surface of the knob. That part of the plastic is quite thin and easily damaged by any outward pressure.

This morning I used metal polish to remove corrosion from the brass rings on the outer rim of the large diameter parts of the knobs. I used a fine-bristle toothbrush to clean the flutes on the sides of all the knobs. Warm water and some soap worked wonders on cleaning those flutes out. When done they look like new again. I have new brass caps on order which will not arrive until after Christmas. When those come in, I will install them using some new clear plastic glue which remains slightly flexible long term. There are far better glues available these days compared to what Fisher used originally. Be careful in your choice of glue. Make sure it is not going to dissolve any of the plastic material. Experiment first on a test surface on the back side of a knob. I would advise against using any cyanoacrylate (super-glue) as it is difficult to work with and not a permanent solution anyway. It will break down in the presence of water or high humidity in addition to being difficult to work with. Its vapors are very dangerous to your eyes and nostrils - extreme burning effect.

I plan to spray the knob brass caps and brass rings with some clear lacquer before replacing them on the amplifier.

Joe

 

[audmod01]

New knob caps arrived yesterday. I cleaned and polished two of the originals and replaced the ones that were missing. They will look nice now. I bought some clear spray lacquer to protect the new and polished older caps. One knob had part of its flutes or ridges break off as I was cleaning the old glue off. I kept the pieces and managed to glue them back in place after the cap was replaced. Now the one knob looks like it always did.

Joe

 

[audmod01]

Yesterday I did get around to installing the knobs after replacing the brass caps, polishing them and coating them with some clear lacquer. They look nice. The front panel received some cleaning too, but still needs more. I did some cursory cleaning of the chassis, but more remains to be done. The chassis is actually in pretty good shape, but has some sort of hardened coating that has darkened and speckled over time. I am trying different solvents on test spots to see if I can find something that will remove the coating without removing the lettering identifying the tubes etc. Here are a few pictures:


I temporarily removed the jewels and have a replacement on order. When it comes in I will install all of them with fresh glue to hold them in place.

I used some Go-Jo waterless hand cleaner (without abrasive) to clean the power and output transformers. They came out looking quite good.

I am somewhat concerned about the output tube sockets. They look to be quite darkened in color. I may look into getting new replacements and change them out. There are still some micalex type octal sockets available, but I need to measure dimensions to make sure I get the right types.

Joe

 

[dcgillespie]

Joe - For what it's worth, Fisher output tube sockets do regularly discolor, but that being said, I've never run across any that were problematic as a result of the discoloration. May I ask what vendor you used for your knob brights? The ones on my own X-202B are nice, but do not include the marker lines.

As typical, you're doing a wonderful job of restoring a Fisher that didn't appear to have much love over its life!

Dave

 

[audmod01]

Dave;
I used a vendor called missiontimes on eBay. The owner is Ken Wong and I was able to buy qty. of 8 of the caps with the dash for $20. There is another eBay vendor that I have obtained volume controls with on-off switches from, captain fantastic.

If Larry is watching this thread, I have a question about using scrubbing bubbles to clean - how long do you leave the application on the chassis before you wipe it off or wash it off? I may not have left it on long enough or else I need to apply it several times. I am going to try again on just the rear top apron that has the output tube types shown on it and see if I can get it to clean off with another application or so of scrubbing bubbles.

On the sockets, they may actually be OK. They are dark, but not burned so I may not need to replace them. Micalex sockets are pretty durable and long lasting. I have only had to replace a few over the years.

I think this one is going to turn out quite well. It just takes the usual love, care and effort.

Joe

 

[bhamham]

Joe,

I've had good results using ammonia, about 10%, to remove that encrusted, darkened layer which might be accumulated nicotine. My experience is that it's safe on the lettering too, but you certainly want to test a small area first. Never used scrubbing bubbles - that might be the way to go. Good luck restoring it, it's looking pretty good now.

Bruce

 

[audmod01]

Latest discoveries:
1) Scrubbing bubbles does a pretty good job removing the grunge. So I have the back panel with the output tube types designated on it cleaned and looking pretty good now. I laid it back in place to take this picture.


2) I began cleaning around the output tube sockets and discovered two things; the no. 2 inboard output tube socket has already been replaced; and also the output transformer for that channel has been replaced with another Fisher correct part numbered unit (whew). I suspect that at some time in the past a coupling capacitor shorted, destroying an output tube and ruining the original output transformer. The replacement tube socket was installed with large nuts and machine screws and I may still decide to replace the sockets for that channel.


In these two pictures you can see the larger hardware used when the output tube socket was replaced.

Overall I am not disappointed in acquiring this amplifier. It did at least receive attention when it developed trouble and the correct xfmr was installed to replace the original unit that failed. I think the careful application of either ammonia or the scrubbing bubbles will take care of much of the rest of the grunge on the chassis and it will look far better when that is done. The backside of the front bezel was also quite dirty with deposited film. It was either from cigarettes or perhaps even from a house fire - difficult to tell. I do not think my nose is sensitive enough to tell the difference since the damage was probably years ago and it has been sitting unused for considerable time. I might know after it is brought up with tubes installed to operating temperatures. That will often cause the odors to be emitted again. If it is too noticeable, it will be subjected to more cleaning as I do not smoke and detest the odor of cigarettes and cigars etc.

Joe

 

[dcgillespie]

What are the tell-tale signs that make you believe that the one OPT was replaced? There is no scratching around the transformer mounting nuts that I can see. From my view, it looks like both transformers are original.

Dave

 

[larryderouin]

Joe; I usually give a foaming coat to the whole chassis, let sit a minute or 2 and start in with a 1" or 2" chip-brush. Lay it on it's side (PT Down) and brush top down. Then I flush it all off with CRC QD Contact Cleaner (and if it's a receiver, the Tuning cap get flushed out too.) It's non residue and works well.

 

[audmod01]

Dave;

You are right and I am wrong about the output transformers. What I noticed first was the difference in construction. The inboard transformer has a bolt-hole slot down through its leaves while the outboard transformer has no slot in its leaves. Also the way the thru-bolts were assembled to the end bells is different. The inboard transformer has two insulator sleeves on the bolts along the short edge while the outboard transformer has two insulator sleeves on the bolts along its long edge. However, both are showing EIA/date code of 9263907 and one is part no. T827-116-1 and the other is T827-116-2. The manufacturer of the transformers must have had leaves and end bells from two different sources and used them to assemble these two transformers. The presence or lack of insulator sleeves on the thru-bolts and their relative positions does not seem to have been important in their assembly practices. I have seen some transformers with insulator sleeves on their assembly thru-bolts at every position while these omitted them at two thru-bolts, but at different physical locations. There seems to be no rhyme or reason for how they were assembled.

It appears that EIA and date codes are more important in identifying originality of transformers than physical construction details.

Larry;

Thanks for the extra details on the cleaning materials and process. I do not have any CRC Contact Cleaner, but will get some before completing the cleaning process.

Joe

 

[audmod01]

I went ahead with using the scrubbing bubbles to clean the chassis top, except did not do the area around the power transformer. I may yet work on that area again. Here is the result so far:

This is pretty decent and far better than what I began with. A few spots of lettering eroded, but I may just make some paper/foil labels and glue them over those particular spots.

One sad discovery today after some closer attention is that every AC Accessory outlet on the back of the chassis is broken! People seem to think they can push a polarized AC plug into an AC socket that is not designed for one - it never works, all that happens is that the socket gets broken and is forever afterward a shock hazard. I will have to look for OEM replacements from donor chassis.

Joe

 

[audmod01]

The jewel I ordered to replace a missing one came in the mail today, so I went ahead and installed it and took this picture:

The order of colors is: green, red, amber, red, green. I will almost always be using the unit in stereo mode and will not be using the phase reverse feature as I will always have speakers connected in correct phase. Modern recordings have correct phase channel to channel so that feature is not too useful any more.

Joe

 

[dcgillespie]

Joe -- The lights indicate channel reverse, not phase reverse. Interesting color arrangement you've used. Most alternate arrangements use a single red jewel for the center channel, and because that lamp lights dimly when the center channel is not activated to act as a power indicator, and then two amber lamps in the "A" and "B" locations.

Lookin' sharp!

Dave

 

[audmod01]

Dave;

OK, I misunderstood your post about the functionality of the mode switch. I understand the function now with your latest comment.

When I received the unit it had two red jewels, one amber and one green. I just arranged them so that they are symmetrical about the amber one in the center.

I have a project I am beginning for a friend to restore a AutoMobile model 100, LW-BC radio from a 1950 Bentley. It is a 12VDC positive ground radio with vibrator power supply. I just did a cursory visual inspection. I see no burned parts, but did discover that the dial cord appears to be broken and the preset tuning push-buttons do not seem to do anything. Band switch push buttons are very slow to move as the lubrication is pretty much all dried up. This is an interesting unit.

Joe

 

[audmod01]

I have a question about the tube shields in the X-202-B. The two driver/phase inverter 12AX7s both have tube sockets that are equipped with the saddle flanges that provide a way to secure the tube shields that Fisher typically use in their equipment. Should these two tubes, V7 and V8 have tube shields also?

Joe

 

[notdigital]

I have a question about the tube shields in the X-202-B. The two driver/phase inverter 12AX7s both have tube sockets that are equipped with the saddle flanges that provide a way to secure the tube shields that Fisher typically use in their equipment. Should these two tubes, V7 and V8 have tube shields also?

Joe

Yup:

 

[audmod01]

notdigital;

I had two extra 9-pin miniature tube shields on hand and have installed both of them now. This should bring the unit up to Fisher standards for shielding.

Is your unit missing the shield that covers the front control area? Mine did at least come with that cover.

Joe

 

[audmod01]

I cleaned the chassis area around the power transformer and then added the two extra needed tube shields. Here are some pictures again:




Next cosmetic item is the bottom chassis cover. The inside is now quite clean from the use of scrubbing bubbles, but the outside has some rust that needs removing and then I can paint it with some aluminum silver spray paint, put the feet back on and re-install it on the chassis.

Joe

 

[rufleruf]

I have a 500-C that had the same differences in output transformers. I thought one had been replaced but there was no evidence of it.

 

[audmod01]

I made one other discovery about the unit's chassis. the middle of the chassis on the right side (viewed from the front) was bent downward some. I noticed first that the bottom cover was slightly bent. I was able to place a small screwdriver shaft under the middle and put some of my weight on the front and back and straighten the chassis. The left side was straight.

Joe