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Beardyman · 10th Mar 2019, 4:53 pm

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.

10th Mar 2019, 4:53 pm	#1
Beardyman Hexode Join Date: Jan 2018 Location: Portsmouth, Hampshire, UK. Posts: 428	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. Attached Thumbnails __________________ The difference between stupidity and genius is that genius has its limits. (Einstein)