UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Audio (record players, hi-fi etc)

Notices

Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment.

Closed Thread
 
Thread Tools
Old 4th Dec 2020, 7:22 pm   #21
stevehertz
Dekatron
 
stevehertz's Avatar
 
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 8,809
Default Re: Armstrong 600 series tuners and receivers

Quote:
Originally Posted by Ted Kendall View Post
Quote:
Originally Posted by Radio Wrangler View Post
Armstrong might have been precarious around the time, it was their last gasp as a manufacturer.
The 600 series sold well for several years - I think in the end they were outflanked by the flat-earth tendency, whose darling they never were. Those in charge pulled the plug when the 700 series was barely launched, deciding that the land was worth more than the business.
Yes the 600 series sold remarkably well, and in hifi terms for a very long time span too, something like '73 to '79? The reviews at the time were kinda fence sitters, but they (the reviews) did improve as did the receivers etc during their lifetime. I think a big selling point was their looks, very handsome, very dinky and British to boot. Yes it was shame that their holding company considered the land to be a bigger asset than the products. But then, they would have had to develop a new range (which was under way), but of course the hifi world was changing. From their perspective, ie purely financial, I don't think anyone could argue with the decision to stop manufacturing and sell the land, sad though that is.
__________________
A digital radio is the latest thing, but a vintage wireless is forever..
stevehertz is offline  
Old 4th Dec 2020, 7:38 pm   #22
Radio Wrangler
Moderator
 
Radio Wrangler's Avatar
 
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,801
Default Re: Armstrong 600 series tuners and receivers

It was not a good time to be in the hifi business, when your produce became judged on parameters you could not measure objectively and you could not yourself discern, and you didn't even believe in. The fickleness of fashion.

A colleague had Armstrong 600 series tuner and amplifier. They worked well for him and sounded OK. He was quite keen on having equipment he liked (Hydraulic reference, SME 3009, V15 and Leak 2075 speakers) The little Armstrong looked a bit small.

The circuitry I saw of the 700 series made it a shame that it didn't make it as a product. But I understand their feelings. My amplifier is something I would not have chosen to throw into the bearpit that the hifi world was becoming at that time. A small run of them was made at HP and that's been it. It sits there in the lounge and just works. I'm happy with it.... It does also contribute one extra bit of entertainment - whenever an audio aficionado meets it, it's hilarious to watch them completely sieze-up. There are no badges, it's not recognisable. It's obviously special and very professional, and the poor souls haven't a clue what they are supposed to say about it. They daren't say what they hear because they might say the wrong thing and be found out at a later date.

But Armstrong came from being a radiogram chassis firm and their earlier amplifiers were not much removed, but with the 600 series, they had made a big jump in what they produced, and you have to respect that.

David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
Radio Wrangler is offline  
Old 4th Dec 2020, 11:23 pm   #23
vidjoman
Dekatron
 
Join Date: Jun 2013
Location: East Sussex, UK.
Posts: 3,315
Default Re: Armstrong 600 series tuners and receivers

Agree, no better or worse than other British amplifiers at the time. They all seemed to use the same resistors, Iskra carbon film I believe, and many used miniature Hunts green sleeved capacitors. They could be a problem in that the leads seemed to part company with the body a bit too easily. Certainly sold well as they were different styling to most other products. Usually reliable but the output capacitors seemed to suffer mainly.
vidjoman is offline  
Old 5th Dec 2020, 9:09 am   #24
stevehertz
Dekatron
 
stevehertz's Avatar
 
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 8,809
Default Re: Armstrong 600 series tuners and receivers

Quote:
Originally Posted by vidjoman View Post
Agree, no better or worse than other British amplifiers at the time. They all seemed to use the same resistors, Iskra carbon film I believe, and many used miniature Hunts green sleeved capacitors. They could be a problem in that the leads seemed to part company with the body a bit too easily. Certainly sold well as they were different styling to most other products. Usually reliable but the output capacitors seemed to suffer mainly.
I've just changed the output caps and it has made a difference, strangely the higher register seems to have more sparkle? Is there a logical, scientific explanation for this or am I audiophooling myself? The old ones were leaking badly.
__________________
A digital radio is the latest thing, but a vintage wireless is forever..
stevehertz is offline  
Old 5th Dec 2020, 10:36 am   #25
Ted Kendall
Dekatron
 
Join Date: Jul 2008
Location: Kington, Herefordshire, UK.
Posts: 3,658
Default Re: Armstrong 600 series tuners and receivers

Output coupling capacitors generate some distortion even when in perfect condition - see Self for the details - and a leaking cap isn't going to improve matters, particularly in the matter of bass distortion as its capacitance will have decreased - and distortion products can easily have a subjective effect on treble clarity. So I wouldn't say that was audiophoolery, especially as measurements would have confirmed what was going on.
Ted Kendall is offline  
Old 5th Dec 2020, 11:05 am   #26
Radio Wrangler
Moderator
 
Radio Wrangler's Avatar
 
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,801
Default Re: Armstrong 600 series tuners and receivers

Reduced ESR, so reduced output impedance.

David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
Radio Wrangler is offline  
Old 5th Dec 2020, 11:11 am   #27
stevehertz
Dekatron
 
stevehertz's Avatar
 
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 8,809
Default Re: Armstrong 600 series tuners and receivers

Quote:
Originally Posted by Ted Kendall View Post
Output coupling capacitors generate some distortion even when in perfect condition - see Self for the details - and a leaking cap isn't going to improve matters, particularly in the matter of bass distortion as its capacitance will have decreased - and distortion products can easily have a subjective effect on treble clarity. So I wouldn't say that was audiophoolery, especially as measurements would have confirmed what was going on.
Thanks Ted, so I'm not ready for my audiophoolery badge just yet.. but yes, it does sound generally 'better' for changing those output caps. I'm hoping the replacement main smoother arrives today. Not sure how much difference that's going to make, we'll see. I've upped it from 3300 to 4700 although I am aware that final versions used 7500. Anyway, the 4700 was reasonably priced and available so that's what I got. I'm not planning on using it daily at high volumes it's more for my collection of receivers.
__________________
A digital radio is the latest thing, but a vintage wireless is forever..
stevehertz is offline  
Old 5th Dec 2020, 12:59 pm   #28
Trevor
Octode
 
Join Date: Aug 2006
Location: Stoke-on-Trent, Staffordshire, UK.
Posts: 1,082
Default Re: Armstrong 600 series tuners and receivers

The Armstrong do in fact include the output capacitor in the feedback loop so in some respects it effects are mitigated
But lets be honest these are getting on for 40 years old not unreasonable to replace at this time I feel
Trev
Trevor is offline  
Old 5th Dec 2020, 2:15 pm   #29
stevehertz
Dekatron
 
stevehertz's Avatar
 
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 8,809
Default Re: Armstrong 600 series tuners and receivers

Given that the 626 had a long life span in the shops, there are/were quite a few variants of data and schematics over that time. I have a service information document that says set quiescent current to 5mA. I have a schematic that says 20mA. What to do? 10mA?! Oh, the documents aren't dated, plus circuit changes were made as I say above.
__________________
A digital radio is the latest thing, but a vintage wireless is forever..
stevehertz is offline  
Old 7th Dec 2020, 7:30 pm   #30
stevehertz
Dekatron
 
stevehertz's Avatar
 
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 8,809
Default Re: Armstrong 600 series tuners and receivers

Having changed the two output caps, I've just done the main smoother too. In all cases the new caps were at least half the size of the originals. This has never been a problem to me, a joy in fact (more space to work in!), I've never seen the point of stuffing caps on a piece of 70s or 80s hifi. The two speaker caps were 30mm diameter as opposed to 45, so I used 35mm cap mounting clips and filled in the gap with a short length of plastic plumbing pipe. I filed semicircular slots into the sides of the original caps chassis holes to accommodate the mounting nuts and bolts. The originals were a push fit into clips. The main smoother simply tie wraps onto the side of the chassis so no issues there. Before and after photos below. Incidentally, I did these repairs on separate days and in both cases the sound and general performance was improved.
Attached Thumbnails
Click image for larger version

Name:	20201204_142439.jpg
Views:	108
Size:	138.1 KB
ID:	222052   Click image for larger version

Name:	20201207_174151.jpg
Views:	106
Size:	100.2 KB
ID:	222053   Click image for larger version

Name:	20201204_142456.jpg
Views:	111
Size:	136.5 KB
ID:	222054   Click image for larger version

Name:	20201207_174223.jpg
Views:	112
Size:	146.9 KB
ID:	222055  
__________________
A digital radio is the latest thing, but a vintage wireless is forever..
stevehertz is offline  
Old 7th Dec 2020, 7:45 pm   #31
Trevor
Octode
 
Join Date: Aug 2006
Location: Stoke-on-Trent, Staffordshire, UK.
Posts: 1,082
Default Re: Armstrong 600 series tuners and receivers

Good piece of work !These units deserve to be maintained they were at the time medium high end I do rather get fed up of people knocking British audio Armstrong always strived for quality Dealing with the factory was never less than a pleasure they were always helpful re service tec.
I also liked the earlier 400/ 500 series very innovative
Trev
Trevor is offline  
Old 7th Dec 2020, 8:23 pm   #32
stevehertz
Dekatron
 
stevehertz's Avatar
 
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 8,809
Default Re: Armstrong 600 series tuners and receivers

Now on to the next fault. AM does not work, no rushing, tuning noises, nothing. But not quite.. if I turn the volume up FULL, the set sits there vibrating like an expectant spaceship seconds before take off (actually that's just a bit of theatre added for interest), I can just about, at less than a gnat's whisper volume, tune in to and 'hear' Radio 5 live (my strongest MW channel), though I cannot hear what they're saying it's so quiet. Strangely, this through one speaker only, and the other speaker sounds like it would with an unused line level input selected but with the volume up full ie amp noise. Interestingly, there's no AM noise, no tuner noise. This suggests to me that the tuner and agc are working but further down the line the signal level is being lost. FM works fine.
__________________
A digital radio is the latest thing, but a vintage wireless is forever..
stevehertz is offline  
Old 8th Dec 2020, 9:09 pm   #33
Trevor
Octode
 
Join Date: Aug 2006
Location: Stoke-on-Trent, Staffordshire, UK.
Posts: 1,082
Default Re: Armstrong 600 series tuners and receivers

EI can remember as a 19 year old looking into a 626 receiver taking the lid off and gazing into the works! All modular construction gone were the unreliable connectors of the 400/500 series I could see how all was built as sub assemblies looking at the schematic with its enhanced VAS stage I really felt I was looking into the future
Build quality seemed to be good and the deign was brilliant the slim looking design was a master of subterfuge
I sold as many as we could get
Trev
Trevor is offline  
Old 8th Dec 2020, 9:25 pm   #34
stevehertz
Dekatron
 
stevehertz's Avatar
 
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 8,809
Default Re: Armstrong 600 series tuners and receivers

Any ideas about the AM fault?
__________________
A digital radio is the latest thing, but a vintage wireless is forever..
stevehertz is offline  
Old 8th Dec 2020, 10:04 pm   #35
Trevor
Octode
 
Join Date: Aug 2006
Location: Stoke-on-Trent, Staffordshire, UK.
Posts: 1,082
Default Re: Armstrong 600 series tuners and receivers

look at the diode logic switching you can use a scope or signal tracer to see if it has Am output I leaky capacitor may be the problem
Trev
Trevor is offline  
Old 8th Dec 2020, 10:07 pm   #36
stevehertz
Dekatron
 
stevehertz's Avatar
 
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 8,809
Default Re: Armstrong 600 series tuners and receivers

Thanks Trevor. Which board is that?
__________________
A digital radio is the latest thing, but a vintage wireless is forever..
stevehertz is offline  
Old 8th Dec 2020, 10:10 pm   #37
Trevor
Octode
 
Join Date: Aug 2006
Location: Stoke-on-Trent, Staffordshire, UK.
Posts: 1,082
Default Re: Armstrong 600 series tuners and receivers

If you look at this site under Armstrong
http://ukhhsoc.torrens.org/AudioDocs.html
you will find the full schematic and this shows the board top left hand side
Trev
Trevor is offline  
Old 8th Dec 2020, 10:14 pm   #38
stevehertz
Dekatron
 
stevehertz's Avatar
 
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 8,809
Default Re: Armstrong 600 series tuners and receivers

Quote:
Originally Posted by Trevor View Post
If you look at this site under Armstrong
http://ukhhsoc.torrens.org/AudioDocs.html
you will find the full schematic and this shows the board top left hand side
Trev
I have all the data, schematics etc Trev, do you know the board designation ? The AM board? Thanks.
__________________
A digital radio is the latest thing, but a vintage wireless is forever..
stevehertz is offline  
Old 9th Dec 2020, 7:20 pm   #39
Trevor
Octode
 
Join Date: Aug 2006
Location: Stoke-on-Trent, Staffordshire, UK.
Posts: 1,082
Default Re: Armstrong 600 series tuners and receivers

the diode logic switching board is the one with the din inputs on it below the chasis
Trev
Trevor is offline  
Old 9th Dec 2020, 7:45 pm   #40
PaulR
Dekatron
 
PaulR's Avatar
 
Join Date: Oct 2003
Location: Southport Lancashire, UK.
Posts: 3,221
Default Re: Armstrong 600 series tuners and receivers

Are there separate switches for AM & FM? If not it would suggest that the AM only fault is further back
__________________
Paul
PaulR is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 6:38 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.