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Success Stories If you have successfully repaired or restored a piece of equipment, why not write up what you did and post details here. Particularly if it was interesting, unusual or challenging. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

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Old 8th Jul 2019, 4:54 am   #1
FStephenMasek
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Join Date: Jul 2011
Location: Mission Viejo, California, USA
Posts: 62
Default F. Stephen Masek's HMV468 restoration

I'll add more posts to this thread as the restoration progresses.

This radio has been sitting in my garage for too many years. I've now got it on one of my work tables, with the chassis removed. The cabinet front and sides are good enough to save, but not the top, so I may just refinish the top. I'll try.

I bought this at a sale in San Diego at the home of a deceased collector. Somebody did some work on it, but most components appear to be original. A Marconi model seems to have the same chassis.

https://i269.photobucket.com/albums/...ssis%20out.jpg

https://i269.photobucket.com/albums/...as%20found.jpg
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Old 28th Oct 2019, 5:14 pm   #2
FStephenMasek
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Location: Mission Viejo, California, USA
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Default Re: F. Stephen Masek's HMV468 restoration

It is finally on my work table. The schematics I have show a resistor in series with the field coil, but this radio was built with another choke in series with the field coil. It is original, as it supports the terminal board for the cable to the speaker.

The two large Bakelite blocks for resistors and capacitors under the chassis are also different that what is shown for the Marconi models.

It would be nice to have a schematic for this radio, but I will probably have to draw it by modifying the Marconi schematic.

The choke and terminal board (I untied the wires to trace the circuits)
https://i269.photobucket.com/albums/...028_085645.jpg

The main power fuse, an unusual (to me) yellow thing
https://i269.photobucket.com/albums/...028_085657.jpg
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Old 28th Oct 2019, 5:32 pm   #3
g8jzyian
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Join Date: Jan 2009
Location: Liverpool, Merseyside, UK.
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Default Re: F. Stephen Masek's HMV468 restoration

Hi
Unless I am mistaken the yellow thing is a heat coil protector that I saw used to protect strowger switches on 50 volt exchanges. As the coil in the device heats up with excess current through the coil the solder holding the pin in melts and the spring in the mount pulls the pin out of the body.
Regards
Ian
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Old 28th Oct 2019, 9:03 pm   #4
FStephenMasek
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Location: Mission Viejo, California, USA
Posts: 62
Default Re: F. Stephen Masek's HMV468 restoration

Somewhat like a fire sprinkler in which a link holding a plug in place melts.

It would be nice to find a schematic for this model, but it may not exist.
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Old 3rd Nov 2019, 6:55 pm   #5
FStephenMasek
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Location: Mission Viejo, California, USA
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Default Re: F. Stephen Masek's HMV468 restoration

It seems closer to the HMV 467 Model, as it has a tapped field coil with one end grounded, and two chokes in the power supply.

It has a fuse between the center tap of the high voltage winding and ground, a nice feature to prevent destruction of the power transformer.
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Old 10th Nov 2019, 6:39 am   #6
FStephenMasek
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Default Re: F. Stephen Masek's HMV468 restoration

I've made good progress. The capacitor block is rebuilt and ready to re-install. I stripped the cabinet today, revealing very nice wood grain on the front, and a water mark on the top, probably from a houseplant. I'll use wood bleach, and stain the top and sides to obtain an even color. The Marconiphone 276 schematic is the closest I have found to this model.



The capacitor block out and the top with the terminals removed
https://i269.photobucket.com/albums/...16%20small.jpg

The rebuilt capacitor block. I cut away unneeded parts of the can. I noticed that one corner of the can had shorted to a wire going to the rectifier tube. That edge is now gone, and I've patched that wire.
https://i269.photobucket.com/albums/...00%20small.jpg

I am grateful that the water damage on the top is not bad.
https://i269.photobucket.com/albums/...10%20small.jpg

The original grille cloth is made with red, olive green and gold yarn or thread.
https://i269.photobucket.com/albums/...26%20small.jpg

I saved the best for last in this post. Look at that beautiful veneer on the front which was hidden under the darkened and deteriorated old finish.
https://i269.photobucket.com/albums/...32%20small.jpg
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Last edited by FStephenMasek; 10th Nov 2019 at 6:59 am.
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Old 10th Nov 2019, 6:19 pm   #7
FStephenMasek
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Default Re: F. Stephen Masek's HMV468 restoration

The chassis mounting arrangement. I will have the red rubber pieces re-made.
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Old 10th Nov 2019, 8:36 pm   #8
Ian B
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Default Re: F. Stephen Masek's HMV468 restoration

Very impressed with the work so far. It's a shame that the clock ( being designed for 50hz mains in the UK0 won't be accurate on your 60 hz.

Ian
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Old 11th Nov 2019, 5:09 am   #9
FStephenMasek
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Default Re: F. Stephen Masek's HMV468 restoration

I will find a way to operate the clock. It does not need much current, so some sort of relatively simple converter should be possible. Perhaps I will return the radio to Europe, perhaps to the flat Rima and I own in Vilnius, Lithuania.
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Old 17th Nov 2019, 3:33 am   #10
FStephenMasek
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Default Re: F. Stephen Masek's HMV468 restoration

It is alive, at least from the 3rd valve through to the speaker. I was able to connect a signal generator to the grid of the 3rd valve and heard the 400Hz tone in the speaker. It had a VP4A in the 3rd position, instead of a VMS4B. I tried switching the VMS4B in the 1st position into the 3rd position, with the same result. That tells me both valves work, at least somewhat. The MH4 oscillator becomes warm, but I've not yet determined if it is oscillating.
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