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Radford STA25 Mk III -- a lot of questions.

I read somewhere that a tiny bit of oil on the pins will be helpful. Perhaps those in the know can advise.
 
Get a torch and shine it into the valve holders, check for anything that might have perhaps fallen in there whilst in transit. Have a look from the underneath too. If necessary post photos here.

Unlikely it would have happened to both however. I think as others have already said you just need to apply a gentle but firm pressure, along with a slight rotating movement to get them in. Sometimes they do need a little persuasion.
 
Here’s an image

72-C58948-BDF8-4270-9164-4-BBF5-D824-AB9.jpg
 
I don’t know how much experience you have in removing/ inserting valves so apologies if this appears egg sucking it’s not meant to be!

Align the dimple, and try using a rocking motion to ease the tube into the socket (same for removal), it shouldn’t require much force at all. If you google this there will be videos on the rocking/ rolling technique.
 
Well I can’t do it.

But on the positive side, I’ve just arranged with someone who knows Radfords (Henry) to take the amp to him tomorrow, that way we’ll get to know what’s going on.
 
For the sake of completeness of this thread, I post this image of the back plate, which is attached very insecurely.

A188238-F-075-C-4-E5-D-93-A4-FA478775-E49-D.jpg
 
Over the years I've found that some combinations of valve and socket can be particularly reluctant - I've always assumed it was tolerances of both the socket and the pins, but also the pins and the contacts can corrode over time increasing the friction. I had some contact cleaner / lubricant that I 'acquired' when I worked in electronic assembly that helped a lot, and I think it was this:

https://www.amazon.co.uk/dp/B01N91F0D7/?tag=pinkfishmedia-21

With smaller valves the rock and roll technique works well, but the octal socket doesn't allow quite as much lateral movement - probably a good thing, as you really don't want to snap the pins off!
 
This site contains affiliate links for which pink fish media may be compensated.
Yes but I can’t remember the details, he rang me while I was in the supermarket so It wasn’t easy. He gave me the impression that he’d identified the cause of the failing capacitor and had fixed it all.

I have managed to get the valves seated properly, thanks to the help of an excellent local company, Unilet in New Malden.

There is still only one channel working. I’m sure it’s the amp - if you swap amps everything’s fine!

Obviously amps can get damaged in the post.
 
Marchbanks said:
Have you tried swapping the smaller valves from one channel to the other?
Click to expand...

Yes I have, I’ve done what Jez said - the only thing I’m not prepared to do is swap the big valves, given that I’ve developed big-valve-phobia!

Arkless Electronics said:
Try re-seating them and then swapping them between channels. Double check wiring to speakers etc etc. It seems beyond unlikely that any repairer would send it back with one channel not working so it must be something silly...
Click to expand...
 
I have a working STA25 Mk3!!

I spoke to Nick at Emporium this morning. He asked if I knew that the order of the smaller valves is important. I said I didn’t, he took me through what to do get them in the right order and now it’s playing just fine.

I’m much relieved as you can imagine.
 
Yes, it’s very good indeed, it sounds wonderful once it’s warmed up!

My plan is to wait a few months and then get it serviced.
 
Marchbanks said:
You can download the ‘technical instructions’ from Radford Revival’s site.
Click to expand...


I was hoping for something a bit more . . . lyrical, poetic.

Something which will explain in words of one syllable and pictures but NO diagrams about order of the little valves etc.

Something that begins

"Congratulations on buying the Radford STA25, the world's greatest amplifier . . ."
 
As a matter of interest what phase splitter valves do you have fitted? (second one in, after the EF86 which is the first and nearest the phono sockets).
 
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