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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 10th Mar 2019, 4:53 pm   #1
Beardyman
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Default Defiant MSH902

Today the Defiant MSH902 got its first taste of electrons for quite a while I suspect. It's been a challenge to say the least, there are no diagrams for this particular model. I even contacted the Co-op archive but no luck. I ended up drawing my own (rather unconventional) diagrams. They did the job & they can be tidied up later. I have many photos, notes & drawings to go through I expect it will keep me occupied for the next few months. Every single capacitor (bar one) was either short/open, so far out of tolerance it wasn't worth the chance or leaked like the proverbial seive both electrically & mechanically. The same went for the resistors ie a 35K measuring at 70K is just an example. Every resistor was high by at least 75%-100%. It's always a nailbiting moment when you've done all the static resistance checks you can do & you plug it in. Without Ed Dinning's help I would not have been able to rescue the transformer, it had an open primary tapping but after taking his advice it soon became apparent there was a manufacturing defect from 1935! A dry joint, simple as that. Aerial attached & fingers crossed power was applied, the scale lamps lit, filaments coming up nicely, HT building, then...... static! Not bad, have a tune around, found radio 4, radio solent, radio 5 live. This particular model has a pickup input, switched it over to that and the unmistakeable sound of arcing! Switch off quick! The multi way switch is a thing to behold, 12 wafers deep with 3 positions. I'd had this out a while back to clean it up but obviously I hadn't been thorough enough, one wire position (carrying HT I might add) was arcing to chassis, not much but enough. Turns out it was just dust/dirt, phew! This set turns the HT off to the RF end of things & that switch just happened to be a bit iffy. It's tuned to radio solent right now and sounding very good. It's been an adventure, I now know what the control that adjusts two inductors is for, sensitivity. Anyway, I thought you might like to see some pictures. Have a good afternoon one & all.
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Old 10th Mar 2019, 5:44 pm   #2
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Default Re: Defiant MSH902

Nicely done! That lacing is very professional. What sort of aerial are you using?
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Old 10th Mar 2019, 6:24 pm   #3
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Default Re: Defiant MSH902

looks lovely.
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Old 10th Mar 2019, 9:55 pm   #4
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Default Re: Defiant MSH902

Having spent some years as a prototype wireman I decided to resurrect my lacing skills! It seemed the right thing to do. All the wiring to the speaker was rotten & in an unsafe state. I could have used ordinary wire but felt it needed the braiding just to make it look "right". The lacing was just a way of holding it all together. The aerial is quite literally a random length of wire strung across my workroom, about 8-10 feet in all. This set had a mains aerial which (through capacitors) used the house wiring as an antenna! I've taken that out as it was just too dangerous for my liking. I've kept the original parts though. It was in a bit of a state when it arrived but all the valves were good luckily. Heres a photo of it "untouched".
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Old 11th Mar 2019, 1:08 am   #5
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Default Re: Defiant MSH902

Really like the grain on the front panel. I'm one of those who still prefers a wooden case to bakelite. Looks better and sounds better too, so what's not to like.

Must have taken some hours work to achieve that level of finish. I'd be interested to hear more about the materials and methods used to achieve such a standard.

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Old 11th Mar 2019, 4:33 am   #6
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Default Re: Defiant MSH902

A wonderful job done there , especially as information on Defiants is so difficult to come by!
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Old 11th Mar 2019, 9:16 am   #7
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Default Re: Defiant MSH902

The case wasn't actually too bad once all the grime & dust was taken off. A bit tatty in places but pretty solid. The old varnish was quite patchy (sun & hot tea cup damage mainly) so was stripped off using acetone & 0000 wire wool & copious amounts of rags! Then it was allowed to dry out for a few days, a quick going over with wire wool to remove any "pips" then wiped down with acetone & lint free cloths. A liberal application of Danish oil, wait a couple of weeks, inspect for blemishes, attend to those then another coat of Danish oil. I have very limited wood working/finishing knowledge/skills and I am very pleased with the end result. Hopefully, once I get all the photos & diagrams together, I can document it properly. Many thanks for all your comments, much appreciated.
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Old 11th Mar 2019, 6:58 pm   #8
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Default Re: Defiant MSH902

That looks fantastic; my enthusiasm to tackle mine, which looks in very similar condition to your 'before' pic, has returned and with the help of your diagram I will try and get mine going.
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Old 12th Mar 2019, 8:50 am   #9
Beardyman
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Default Re: Defiant MSH902

Murphy Maniac,
I'll re-iterate that my diagram may well contain errors as I've not yet had a chance to thoroughly go over it. It's pretty darn close though. If I can help at all then please drop me a line & I'll see what may be done. I did some other drawings regarding the multiway switch, what gets switched in & out etc. so if you would like them I'll email them over to you. Mine sounds very bassy but muffled at the higher frequencies, just as they used to back then! Plenty of volume as well. My chassis was filthy, black greasy deposit everywhere. Best of luck with yours, keep in touch.
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Old 14th Mar 2019, 11:46 pm   #10
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Default Re: Defiant MSH902

That's very kind of you Beardyman, any copies of the drawings would be most welcome. Sadly I am plagued by funerals at the moment; Why do they always seem to come in threes? Once things settle down a little, I intend getting back into my workshop, and the Defiant is first on my list. I will indeed let you know how things are going and report on performance.
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Old 15th Mar 2019, 1:15 pm   #11
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Default Re: Defiant MSH902

I enclose some 'before' pics of my Defiant which, for some reason unknown, have come out on their side. Afraid that you will have to lie down to view them!
Best Wishes,
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Old 19th Mar 2019, 5:08 pm   #12
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Default Re: Defiant MSH902

Lovely job, Beardyman. That lacing is very professional.

I know that some others don't like it but I find that Danish oil gives good results and is very easy to use. As it doesn't sit on the surface it is also much less prone to damage than other types of finish.
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Old 20th Mar 2019, 8:59 am   #13
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Default Re: Defiant MSH902

Murphy Maniac,
Good pics! I note that your speaker is a ROLA whereas mine is a JENSEN, not that it makes much difference I suspect. Also your speaker switch has been disabled shall we say!
It looks in somewhat better shape than mine internally though. The chassis is darn heavy when out of the cabinet & seems to have a preference for resting on its transformer! I'm sure you'll have lots of fun with it. One thing was that the tuning dial had shrunk considerably so I had to re-mount it on thin (1mm) polypropylene sheet, if you should find the same thing has happened then I might have a sheet left that you'd be welcome to.

PaulR,
I would be the first one to admit that my woodworking skilss are extremely limited which was why I chose Danish oil! Quite difficult to mess it up & if you do you have several hours/days to get rid of it! I'm more at home with metal, that can always be welded/built up but wood doesn't respond quite the same way!
I hadn't actually laced anything for over twenty years before I did that but the callouses are still there on my index fingers.

Have a good day one & all.
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Old 24th Mar 2019, 10:32 pm   #14
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Default Re: Defiant MSH902

I've not seen this model before, well done on a first class job the set looks great.
I have a soft spot for 1930's wooden radios, the golden age in my books.
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Old 25th Mar 2019, 9:24 am   #15
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Default Re: Defiant MSH902

What a lovely radio ,not seen that model before It look like the painted chassis has survived well ,well done with the restoration , Mick.
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Old 27th Mar 2019, 8:43 am   #16
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Default Re: Defiant MSH902

The set has developed a fault! After about 10-15 minutes the sound fades down a bit & most of the bass goes, does the same on the gram input so I'm thinking it's in the AF stage. Hopefully it's something like a faulty AC2PEN & not any of the inductors etc, I'll need to take some measurements over the weekend. The chassis did survive well all things considered but as I mentioned previously the underside was covered in some black sticky deposit. Something like the wax from the capacitors & coal dust! There really isn't a lot out there about the Defiant radios in general. I only got this one as it was cheap (35) & I fancied something different, I liked the look of it to which helped. Have a good day one & all.
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Old 27th Mar 2019, 9:03 am   #17
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Default Re: Defiant MSH902

Check the voltages around the output valve anode, grid 1 and cathode from switch on till the fault appears then you will know where to look.
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Old 8th Apr 2019, 8:34 am   #18
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Default Re: Defiant MSH902

Finally got enough time to look into the fading issue. There is a 35K dropper from the main HT rail to provide HT for the RF/IF stages which when hot (about 60C or so) was drifting down in value to about 22K! This was giving the RF/IF stages a hard time. The main HT rail sits at around 340VDC & the anodes of the ACVP1's & FC4 are rated to 250VDC. Once that resistor was replaced with something a little beefier (perhaps I miss judged the wattage rating of the old carbon rod one? It was about 2.5" long by 0.5" dia. which according to information I found was 5W?) all is now well. Had it running for a few hours afterward with no sign of fading although the tuning does wander a little, forgivable in a radio that's 80+ years old. A happy ending after all. Have a good day one & all.
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Old 8th Apr 2019, 9:33 am   #19
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Default Re: Defiant MSH902

You may find a use for that NTC resistor one day!
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Old 17th Apr 2019, 10:52 am   #20
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Default Re: Defiant MSH902

Now that's a thought Boater Sam! Could well come in handy, off to the "Might Be Useful" box for that one!
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