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 Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players

Notices

Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

Closed Thread
 
Thread Tools
Old 13th Jan 2023, 4:54 pm   #1
Welsh Anorak
Dekatron
 
Welsh Anorak's Avatar
 
Join Date: Apr 2005
Location: North Wales, UK.
Posts: 6,825
Default Stella ST459 motorboating

I can't recall the Philips eqivalent of this - it's a 4-speed, 4-track machine. Unusually for 1964 it's transistorised with OC series transistors.

There's a quiet motorboating (no hum) in the background, varying with the volume in stop. In play it's very much louder, but the playback sound behind the noise is fine. Oddly, in record mode the motorboating is almost silent.

The HT is stable at around -16v and doesn't vary. I've done the usual cleaning of switches but no good. The caopacitors are silver Philips which I haven't had much trouble with in the past, so not my first port of call.

Any ideas?
__________________
Glyn
www.gdelectronics.wales
Welsh Anorak is online now  
Old 13th Jan 2023, 6:07 pm   #2
DMcMahon
Dekatron
 
DMcMahon's Avatar
 
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,520
Default Re: Stella ST459 motorboating

The Stella ST459A/15 and Cossor CR1605A/15 are clones of the Philips EL3549A/15.

David
DMcMahon is offline  
Old 13th Jan 2023, 7:32 pm   #3
peter_sol
Octode
 
Join Date: Aug 2003
Location: Welwyn Garden City, Herts. UK.
Posts: 1,906
Default Re: Stella ST459 motorboating

Have you cleaned the record / playback switch?
peter_sol is offline  
Old 13th Jan 2023, 8:02 pm   #4
dazzlevision
Dekatron
 
Join Date: Sep 2003
Location: Near Swindon, North Wiltshire, UK.
Posts: 3,567
Default Re: Stella ST459 motorboating

Quote:
Originally Posted by Welsh Anorak View Post
I've done the usual cleaning of switches but no good.
Already been done?

Last edited by dazzlevision; 13th Jan 2023 at 8:08 pm.
dazzlevision is offline  
Old 13th Jan 2023, 8:11 pm   #5
PYE 405
Pentode
 
Join Date: Dec 2009
Location: Chatteris, Cambridgeshire, UK.
Posts: 176
Default Re: Stella ST459 motorboating

A total guess here.... too much negative feedback via a high ESR electrolytic?
__________________
Andrew
PYE 405 is offline  
Old 13th Jan 2023, 8:38 pm   #6
Restoration73
Nonode
 
Restoration73's Avatar
 
Join Date: Jun 2013
Location: Surbiton, SW London, UK.
Posts: 2,801
Default Re: Stella ST459 motorboating

Might even be a soldered joint. I have a mint ST459 here, all working except rewind and
play take-up as a thin belt has turned to goo. It is the only machine I have with 15/16ips.
Restoration73 is offline  
Old 13th Jan 2023, 10:16 pm   #7
DMcMahon
Dekatron
 
DMcMahon's Avatar
 
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,520
Default Re: Stella ST459 motorboating

The fact that the motor boating varies with the volume control suggests that the instability/oscillation that is generating the motor boating is occurring in the stages prior to the volume control. So suggest that the other 3 HT supplies, i.e. the -1, -2 & -3 supply rails be checked for stable voltage and also oscilloscope checked (if available) for any abnormalities.

Is it normal with this model that you get sound in the Stop mode ? i.e. many models mute the playback amplifier in Stop mode.

David
DMcMahon is offline  
Old 14th Jan 2023, 4:02 pm   #8
Welsh Anorak
Dekatron
 
Welsh Anorak's Avatar
 
Join Date: Apr 2005
Location: North Wales, UK.
Posts: 6,825
Default Re: Stella ST459 motorboating

Agreed - the fact that the noise is virtually absent in record monitor mode would tend to confirm this. I'll have a close look at the manual then scope the supply rails as you suggest. Last time I used the machine it worked fine - just happened when someone wanted to borrow it, of course...
It's an odd one!
Unusual to have 15/16 ips - the only others I have are, of course, the Uher Reports.
__________________
Glyn
www.gdelectronics.wales
Welsh Anorak is online now  
Old 18th Jan 2023, 11:18 am   #9
Restoration73
Nonode
 
Restoration73's Avatar
 
Join Date: Jun 2013
Location: Surbiton, SW London, UK.
Posts: 2,801
Default Re: Stella ST459 motorboating

Your thread has prompted me to service mine. The rewind belt goo was removed and
although in this early (Sept 1963) /00 version the belt was square, as it is crossover I
decided to use a round belt instead. I also had to remake one of the leaf switches where
the plastic disintegrated. Although the deck was similar to the earlier hybrid machines,
(I moved on my ST454 as it had no 7.5ips) it is an excellent diecast build with a massive
flywheel that you need for 15/16. Works well, low noise. I hope you found your fault.

Last edited by Restoration73; 18th Jan 2023 at 11:35 am.
Restoration73 is offline  
Old 18th Jan 2023, 1:53 pm   #10
Welsh Anorak
Dekatron
 
Welsh Anorak's Avatar
 
Join Date: Apr 2005
Location: North Wales, UK.
Posts: 6,825
Default Re: Stella ST459 motorboating

Well, sort of!
Swinging the PCB out (thanks Philips - nice to have servicing in mind) the sound could be made to come and go, but not a dry joint. Looks like perhaps I'm not the first person here as a couple of wires had been freed from the paper tape loom running around the board. Earthing doesn't help, and it comes back loud and clear when the board is swung home - the earthing screws have no effect.

Moving the wires does help and it's almost usable so it's now waiting for inspiration...

However please let me know if your machine shows any sign of this noise.
__________________
Glyn
www.gdelectronics.wales
Welsh Anorak is online now  
Old 19th Jan 2023, 9:05 am   #11
DMcMahon
Dekatron
 
DMcMahon's Avatar
 
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,520
Default Re: Stella ST459 motorboating

Could it be a screen off a screened cable that has broken away/come disconnected ?

David
DMcMahon is offline  
Old 19th Jan 2023, 3:11 pm   #12
Welsh Anorak
Dekatron
 
Welsh Anorak's Avatar
 
Join Date: Apr 2005
Location: North Wales, UK.
Posts: 6,825
Default Re: Stella ST459 motorboating

Not that I can see, and it does act like it's picking up the interference from somewhere, but it's too slow to be from the motor or miains hum - maybe 4 clicks a second. Odd!
__________________
Glyn
www.gdelectronics.wales
Welsh Anorak is online now  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 3:07 pm.


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.