B261 Revox FM tuner - stock faults?

[Martin G7MRV]

I'd noticed, but was doing as commanded by the missus!

Ive just snuck out and plugged the DTL10's in, and a croc clip lead for an antenna, I couldnt resist,

my, it sounds amazing! I thought my Ravensbrook sounded good, but this is like listening to the test point on the output of the omnia processor at the station!

Definitely the best thing ive ever pulled from a skip!


Edit - Oh boy! Ive just seen what prices these are going for! Im not selling, but it also means im not going to be able to find the missing bit of trim cheap!

[Radio Wrangler]

Fate has a sense of humour.

I was standing in the queue in the rain waiting for the doors to open at the G-QRP doo and a chap joined the line carrying something biggish which he was trying to shelter under a single plastic carrier bag.

Good grief! that looks like a... Hell's teeth, it is!

Revox B261

He was going to put it on the bring and buy stand. His asking price was acceptable, so it never made it into the hall

It's an ex-beeb variant. Some bits have been removed and it has a single antenna input. Bizarrely, the input is a chassis mounted MALE Belling-Lee connector. The mains input is a regular IEC 3-pole job.

A pair of headphones and a bit of wire while I was still down in Huddersfield showed me it works. There's a bit of mains hum which increases with the volume pot, so I need to go round the power supply decouplers and reservoirs. I suspect somethings getting onto the tuning line or the VCO power supply.

It has rack ears fitted and not the plastic side-cheeks. The chance of finding a pair of those is zero-ish but stranger things have happened. I think I need to get a couple of bits of nice hardwood and get the router going. I'd be tempted to go for oiled rosewood, but originality would require routed wide, shallow grooves and grey paint.

So from not having had a tuner in my hifi system for a lot of years, I've now got two very serious ones with the Sony STS770ES and B261.

What I'm wondering is who did I meet in the queue?

David

[Nickthedentist]

Wow, lucky find, David!

Originally Posted by Radio Wrangler

Bizarrely, the input is a chassis mounted MALE Belling-Lee connector.

That's actually a very common arrangement, particularly on Japanese gear.

N.

[Herald1360]

It's also logical, in the sense that inputs should be plugs and outputs, sockets- ref the mains connector. Not the same safety consideration, perhaps.

[vidjoman]

Originally Posted by Nickthedentist

That's actually a very common arrangement, particularly on Japanese gear.

Very common on Hi-Fi Tuners. Think it was to discourage people to plug it into a TV wall socket. A dual wall socket outlet for TV and FM will have one of each.

[Radio Wrangler]

I've just spent an evening working on the B261.

I was going to have to bite the bullet and pay Farnell's 15 quid charge for US stock to get some power fets for another job, so I had a shop for LED replacements for those 35v festoon bulbs. I bought a selection to try.

They have rectifier bridges so orientation isn't important. THey are rated to run between 190 and 30v. So I fiddled the little mounting board to put them in series off the 35v feed. Current is 40mA which is a lot less than the 170mA the bulbs took.

The ones I decided looked best were 600mW cool white with the original green filter strip still fitted. The display is brighter than the original was - an improvement not a problem.

I've just replaced all the electrolytics on the power supply board, and the hum's gone.
The main reservoirs are Frako parts with heavy steel bases and three ground lugs around a central positive. they are the very devil to get out without lifting pads on the board.

As I was going to have the board on the bench it made sense to do a full replacement. It wasn't expensive. I've got the part sitting ready to work through the whole unit. The smaller electrolytics were blue-jacketed radial parts by Philips. 50% of them were discoloured under the jacket, sort of greyish.

So it's playing now on the main system and I'm very happy with how it sounds. THe rack ears are off, and I've found some rubber feet to suit it. I now need some alternative for the plastic side cheeks. Finding any original ones is unlikely. Do I get some thick plastic and get filing and scraping? Or maybe hardwood? Grey paint could look original, but seems a crime on some nice wood. Decisions, decisions...

David

[Radio Wrangler]

In view of earlier posts, I can report that the beastie seems to be a tantalum-free zone.
Even the little 10uF 35v radial cans are too light to be anything but aluminium.

David

[Radio Wrangler]

Latest instalment:

The four reservoir capacitors I measured look OK on a Peak ESR meter, capacitance within the right ballpark and 0.04 Ohms ESR

On the other hand the small capacitors from the power supply board are ALL bad. One - the best one- gave 8 Ohms ESR on a 10uF part. All the rest show over 20 Ohms and one open circuit.

This makes it look like replacing all the electrolytics on all the other boards is a necessity. At least I bought enough.

David

[sp10mk11]

Wow what a find and what an easy repair, I wish you the best of British with this highly desirable beautiful piece of equipment.

In the past when wanting to introduce a piece of gear that might cause adverse comments I have left it sitting around in the livng room for a few days and then put it into the system "for testing purposes" and then sort of left it there..................

[Herald1360]

Good luck! It may take a few days, or it could even be years, but if SWMBO doesn't like the look of it, it'll get its marching orders eventually.