Meck XB-702 restoration

[bandersen]

I was recently contacted by a member of ARCI (Antique Radio Club of Illinois) to see if I was interested in a late 40s 7" set - model unknown.



I was happy to make a solid offer as there was no radio swapfest this year and the proceeds help fund the club.

I also got a tour of his excellent collection and basement workshop. Was able to see some high end radios I'd only seen in photos previously

He sent some photos including the cover of Sams showing a Meck XA-701 that looked similar.

A little detective work and thanks to Riders vol #3 I think we have a positive ID as a model XB-702.

There is a label inside but the model was trimmed off.



First the good. All knobs and present and the chassis appears to be 100% original. Even all four rubber feet are intact and in good condition. Have not tested the picture tube yet.




Now for the bad. It appears to have been stripped using a belt sander that wore through the veneer in a number of places.

At least if I do decide to replace it, it's basic mahogany crosscut veneer.

[bandersen]

Appears to has seen some heavy use. Most of the caps show sings of deterioration.





I dig the high voltage caps and will try to restuff them.


Apparently Meck cut a few corners to keep costs down. There is no AC interlock for example and the power supply is crazy. Similar the the Halicrafters 505.

A 6X5, 25Z6 and a selenium for a total of 5 rectifiers producing -120V, +120V, +250V, +300V and +350V.

[edison64]

You lucky dog you! LOL I live about 20 minutes from Plymouth Indiana where that set was made and I've been looking for one for the better part of 40 years and here you find one... I'll be interesting to watch are you planning on doing videos? If nothing else I can always drool and dream LOL

[Dj3928]

I have a Meck XA-701 that I restored, that chassis looks very similar to mine.
It’s on YouTube, here’s the link If anyone’s interested

1949 MECK 7” TV Restore Part 1 of 4 Analysis and CRT Testing https://youtu.be/7gSGcUju_jM

[bandersen]

I got it up on the backup workbench last night and tried a controlled power up. I was able to squeeze a very dim raster out of it. No change in image or sound when channels are changed.





Every single axial electrolytic has dry, crusty goo coming out so I expect that are all very bad.

I'll tackle the power supply first.

[vortalexfan]

I've got a 1950 Philharmonic (Meck) Model 8200 10" TV that I had finished restoring electrically a couple of years ago, the Philharmonic Model 8200 was basically a Meck XQ-776 TV (the Philharmonic nameplate was due to Meck Industries buying out E. H. Scott in late 1949 which was who originally owned the "Philharmonic" nameplate.)

My TV was bought from someone locally who picked up the from inside an old Farmhouse in Mishawaka, Indiana that the roof had collapsed on it over 20 years ago and the solid walnut cabinet was still in excellent condition yet considering the conditions the TV was stored in for a while, I stripped and refinished the cabinet myself.

[bandersen]

Very nice. I recall following your restoration progress.

I was a bit disappointed to discover those nifty CCC high voltage caps are actually old replacements. I snipped them out and tacked in replacements. That improved the raster quite a bit.

I also found that the main B+ rail was only about 75 volts. I tacked a 1N5408 diode across the selenium rectifier and that brought it right up. No noticeable improvement though. Loud buzz out of speaker and no hint of reception.

I'll continue to work my way through the power supply.

[Tube TV]

What a cute little TV. I like the simplicity of the cabinet. It reminds me of a simplified National TV-7W.
It's too bad they used a belt sander of it to save a bit of time refinishing. Someone done that to my GE 10T4 also.

[bandersen]

Replaced a few more caps in the power supply with no improvement so I turned my attention to the tubes for a while. It's a rather curious mix.

First, we have one 25Z6 and two 6AL5s branded with MECK




All of the remaining octals are RCA with the same '9-26' date code. 26th week 1949 ?


Then a bunch of MIRROR-TONE branded 6AU6s dated '9-35'. I don't recall ever seeing this brand before.


They all test very good. Could they all be the original tubes?

Also found this label inside. The original owner?

[bandersen]

Based on all the tubes appearing to be original from 1949 and testing strong I would think it was a low hour set. However, all the caps look like hell.

They are all either made by the Industrial Condenser Corp or Chicago Condenser Corp which is still in business today.

Which leads to another mystery. The four HC deflection coupling caps have clearly been replaced. They are wired with clunky "j-hooks". However, they appear to be as old as all the other caps and are also made by CCC.

Could they have failed shortly after the set was sold and replaced under warranty by Meck ?

[kvflyer]

Originally Posted by bandersen

...However, all the caps look like hell.

They are all either made by the Industrial Condenser Corp or Chicago Condenser Corp which is still in business today.
...
Which leads to another mystery. The four HC deflection coupling caps have clearly been replaced. They are wired with clunky "j-hooks". However, they appear to be as old as all the other caps and are also made by CCC.

Could they have failed shortly after the set was sold and replaced under warranty by Meck ?

Bob, I would think that that is a good chance. Thanks for the updates.

[vortalexfan]

I believe my Meck TV which had many of the original caps in it yet had mostly Chicago Condenser Corporation Capacitors in it, I believe they were a very common supplier of components to a lot of Midwestern electronics manufacturers in the 1940s-1960s in fact my 2 Zenith TVs I'm currently working on also had Chicago Condenser Corporation Capacitors in it as well (specifically my "Bugeye" TV, I also had a ton of those in my Zenith Bugeye clock radio and also in my Zenith 10S690 (which has long since been scrapped because I couldn't fix the turntable drawer because I couldn't find any drawer glides that would fit the turntable drawer properly.)

[bandersen]

I replace the four HV deflection caps and got a full raster.
Then, I finally realized I had made a stupid assumption that the channel #s went clockwise. So instead of tuning to my RF signal source on channel 3, I was tuned to channel 12!

I might have had a picture form the start. We'll never know.

The loud audio buzz was caused by a bad cap between the volume control arm and the grid in the audio preamp tube.
Somehow that was causing the high impedance circuit to pick up all surrounding EM radiation. Just moving my hand near the cap cause all sorts of noise.

Replacing the cap resulted in OK sound, but it's way off from the picture. Odd considering this is an intercarrier IF set. The 4.5 MHz pickup coil must be misaligned.



The focus and centering controls are acting flaky now so I'll pull the phenolic sub-assembly out for a going over.
I figure there could be tin whisker or gunk attracted by the static charge.

[bandersen]

Ugh. Replaced a few more paper caps and lost reception. That happened once earlier and wiggling the 6C4 tube in the tuner got it back, but not this time.

The channel selector is also very stiff. I need to get in there for a clean and lube. Haven't quite figured out how to get the shield off yet.

[bandersen]

Rookie mistake. I was interrupted while recapping and forgot to install a new coupling cap between the video detector and video amp

My recently refurbished Tek 454A scope quickly pinpointed the problem.

Recapping is now done on the IF and video circuits and the image is lousy. Also, the tuning is one channel off and sound/video are mile apart on the fine tuning. An alignment is definitely in order.

Also, bad horizontal fold over if I increase the width. Still need to finish recapping the sweep circuits.