Predicta Tandem restoration

[bandersen]

I'd seen Lee (M3-SRT8) touting the virtues of Spray 9 in his restoration threads, but it seemed to only be available on the East coast. Until a few months ago that is when I found it selling in 1 Gal. bulk containers for just a few bucks at a local Home Depot.

Apparently chassis is the plural of chassis http://www.merriam-webster.com/dictionary/chassis

[bandersen]

The topside was pretty grungy too, but I'm slowly making progress cleaning it.


Also, the cabinet is ready for some grain filler.

[bandersen]

I filled the grain with some Constantines red mahogany grain filler. After it dried, I lightly sanded the cabinet and sealed with Deft lacquer sanding sealer.
I managed to get a couple light coats of Mohawk cherry/red mahogany toner lacquer on the cabinet before the temperature dropped 40F Thursday night
It might be a while before I can put on some coats of clear and rub out the finish.


I'll keep plugging away at the electronics in the meantime.

[kvflyer]

Originally Posted by bandersen

I filled the grain with some Constantines...

I'll keep plugging away at the electronics in the meantime.

Looking good as usual! I think that there are very few original components on that PC board! Should work like new or even better.

Thanks for sharing the progress.

[Down Under]

Fantastic job so far! That cabinet is really looking the part.

It's interesting to see the board, I notice that all the components are either parallel or perpendicular to each other. One thing I generally notice about vintage boards is that components just seem to be randomly scattered at crazy angles. Even my Princess and Debutante boards (same thing) are not neatly arranged like your board shown here, yet they were produced by the same company at much the same time. Weird...

[bandersen]

Right you are. Funny, I never noticed that before. Here's the main board from my Princess set with the crazy angles (and plenty of dust).

[Ralph S]

Bob: I'm finishing up my restore of a tandem and I'm trying to figure out how to remove the back of the case from the crt so I can replace the caps, etc. I haven't found any info on a strategy. Have you worked out what to do on this yet?

[bandersen]

Sure. I'll take the case apart like I did with my Holiday set. http://www.videokarma.org/showthread...255328&page=10

The procedure is outlined in the Sams service info. Basically, remove the decorative brass plate, unhook the spring holding the plastic trim and remove the steel strip holding the case halves together.

[Ralph S]

Thanks for the info. I thought it would be a different procedure than the princess, etc., but you're right, it's the same. Came apart very easily and all old caps are gone. Best regards.

[bandersen]

I just got this mahogany base unit from a fellow collector. No legs, no cable, no CRT.

I think I'll use this chassis too as it's relatively rust free. Looks to be 100% original components except for the tubes.



Assuming the paint comes off, all it needs is a little touching up


Unfortunately, the antenna was bent and just barely hanging on. One little flex and it just broke off

[bandersen]

A little 0000 steel wool and 600 grit sandpaper took care of the paint splatters easily After a little more sanding, I'll fill in the dings and clearcoat it with lacquer.

While working on it, I convinced myself that this is actually a photofinish. Odd considering the other Tandem cabinet is really mahogany veneer.

[bandersen]

With another Tandem fresh on my mind, I decided to dive right into finishing this one off.

Rather than continuing with the original corroded, fire damaged chassis, I'll be using the "new" chassis.

The previous owner said it had been stored in a dank, damp basement for many years, but it looks pretty good to me. Minimal corrosion and no repairs. Just a few tubes have been replaced.

First, I tackled the main board.


Here are my replica networks. I used 630v C0G ceramic for most. A couple micas only because Mouser didn't have those ceramic values in stock.

Also, one HV disc cap in the vertical feedback network. It's the yellow cap in the middle.


Here they are after painting, ready to be installed.

[ISawItOnTV]

Great job on those K-nets! (and everything else as well)

[bandersen]

Thanks! Before I reinstalled the main board, I removed a bit of corrosion.


Here's a closer look at that flyback. Some material has melted out the bottom but otherwise it's in OK condition.


Now, I've moved on to working underneath the chassis. It appears to be 100% original. Even the filament dropper and thermistor test OK.
That sand coated dropper is showing green corrosion though so I'm inclined to replace it.



This big multi-section cap is crusty and bulging

[ChrisW6ATV]

Very nice work on those couplates!