Collaro Microgram D/L Cartridge change. - UK Vintage Radio Repair and Restoration Discussion Forum

murphyv310 · 23rd Oct 2008, 2:32 pm

Hello.
I have had for years this 1948 Collaro Microgram Deluxe, its occasionly brought out and played, it always works faultlessly with good audio and plenty of it!
Last time though when I tried it I had noticeable distortion and low audio. I tried all the usual suspects around the amp but all was well.
I then took out the cartridge and it was quite clear it was falling apart I suppose not bad for 60 years. I tried to get one and even posted a wanted on this forum, no luck though. I had a turnover cartridge I got from Musonic a couple of years ago so after removing the bracket and turnover mech I glued it in place to test it out, the result is excellent and I will make the repair permanent.
Trevor

Nickthedentist · 23rd Oct 2008, 2:38 pm

Well done Trevor!

Your repair isn't pretty, but as you say, works perfectly. If the alignment is correct, I'd leave it as it is.

BluTac is another useful material for temporary experiments like this.

Nick.

ben · 24th Oct 2008, 1:26 pm

great work - and what a great piece of kit! must be among the first of its kind - never seen one.

mickjjo · 24th Oct 2008, 1:43 pm

That looks like a good fix, well done, I've got one of those machines with a dead head, I shall have to try that idea!

Regards, Mick.

mickjjo · 25th Oct 2008, 10:04 pm

Inspired by Trevors modification, I decided to bring my own Collaro Microgram back to life. Mine has an all Bakelite arm but the old steel needle Brush crystal pickup head was dead, I fitted a new BSR X5H high output cartridge by extending the leads slightly. The metal fixing bracket has 1/2 inch spaced holes which lined up perfectly and the needle alignment was spot on.
The thing now basicaly worked with ample output but things are never this easy!, the problem being that the tracking weight was around 20 grams

, with no way of adjusting it, the X5H cartridge spec. is 5-9 grams. I played with various coil springs with no success then hit upon an idea I've seen in other pickups, I fashioned a couple of strips of thin bendy phosphor bronze, fitting one to the arm and the other to the the top of the bearing carrier. These "springs" act against each other to relieve some of the weight. By trial and error bending I was able to get the tracking weight down to 7 grams at record height, a simple system but it works just fine!

The rest of the player needed most of the caps changing, a new CY31 rectifier and a good clean and relubrication, The turntable was running at 83 RPM

, a bit too fast, so I shaved a bit off the motor capstan to get it down to just above 78.
The old Microgram now works beautifully and is probably kinder to records than it was 60 years ago, the sound quality is amazing, now playing Louis Armstrongs' 1929 recording of "Some Of These Days", sounds better than the CD issue!...

.

Regards, Mick.

23rd Oct 2008, 2:32 pm	#1
murphyv310 Dekatron Join Date: Sep 2006 Location: Kilmarnock, Ayrshire, UK. Posts: 5,422	Collaro Microgram D/L Cartridge change. Hello. I have had for years this 1948 Collaro Microgram Deluxe, its occasionly brought out and played, it always works faultlessly with good audio and plenty of it! Last time though when I tried it I had noticeable distortion and low audio. I tried all the usual suspects around the amp but all was well. I then took out the cartridge and it was quite clear it was falling apart I suppose not bad for 60 years. I tried to get one and even posted a wanted on this forum, no luck though. I had a turnover cartridge I got from Musonic a couple of years ago so after removing the bracket and turnover mech I glued it in place to test it out, the result is excellent and I will make the repair permanent. Trevor Attached Thumbnails __________________ Cheers, Trevor. MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member

23rd Oct 2008, 2:38 pm	#2
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,873	Re: Collaro Microgram D/L Cartrdge change. Well done Trevor! Your repair isn't pretty, but as you say, works perfectly. If the alignment is correct, I'd leave it as it is. BluTac is another useful material for temporary experiments like this. Nick.

24th Oct 2008, 1:26 pm	#3
ben Dekatron Join Date: Aug 2006 Location: Madrid, Spain / Wirral, UK Posts: 7,500	Re: Collaro Microgram D/L Cartrdge change. great work - and what a great piece of kit! must be among the first of its kind - never seen one.

24th Oct 2008, 1:43 pm	#4
mickjjo Rest in Peace Join Date: Jul 2004 Location: Dartford, Kent, UK. Posts: 1,661	Re: Collaro Microgram D/L Cartrdge change. That looks like a good fix, well done, I've got one of those machines with a dead head, I shall have to try that idea! Regards, Mick.

25th Oct 2008, 10:04 pm	#5
mickjjo Rest in Peace Join Date: Jul 2004 Location: Dartford, Kent, UK. Posts: 1,661	Re: Collaro Microgram D/L Cartrdge change. Inspired by Trevors modification, I decided to bring my own Collaro Microgram back to life. Mine has an all Bakelite arm but the old steel needle Brush crystal pickup head was dead, I fitted a new BSR X5H high output cartridge by extending the leads slightly. The metal fixing bracket has 1/2 inch spaced holes which lined up perfectly and the needle alignment was spot on. The thing now basicaly worked with ample output but things are never this easy!, the problem being that the tracking weight was around 20 grams , with no way of adjusting it, the X5H cartridge spec. is 5-9 grams. I played with various coil springs with no success then hit upon an idea I've seen in other pickups, I fashioned a couple of strips of thin bendy phosphor bronze, fitting one to the arm and the other to the the top of the bearing carrier. These "springs" act against each other to relieve some of the weight. By trial and error bending I was able to get the tracking weight down to 7 grams at record height, a simple system but it works just fine! The rest of the player needed most of the caps changing, a new CY31 rectifier and a good clean and relubrication, The turntable was running at 83 RPM , a bit too fast, so I shaved a bit off the motor capstan to get it down to just above 78. The old Microgram now works beautifully and is probably kinder to records than it was 60 years ago, the sound quality is amazing, now playing Louis Armstrongs' 1929 recording of "Some Of These Days", sounds better than the CD issue!.... Regards, Mick. Attached Thumbnails