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 28th May 2020, 1:09 pm   #1
greenstar
Octode
 
greenstar's Avatar
 
Join Date: Jul 2011
Location: Leicester, Leics. UK.
Posts: 1,681
Default Motor and its capacitor on HMV Q286 radiogram, 1934.

I am making halting progress with this. Have looked at the 78 rpm record deck, which has a beautifully made motor. However, it does not run. Resistance of windings ok. I took out and cleaned the pickup arm operated switch, which would not operate, but now does, but it still does not run. One possible suspect is the large rectangular block capacitor mounted on the motor , but I have no knowledge of these motors, nor can find any information, nor, annoyingly, is there anything on the service sheet, written for the chassis only. It measures at about 20 uF, which seems rather high, but there is no value or working voltage marked. I tried connecting a 3uF poly capacitor, but still no movement. The motor, I suspect, is not 220v, as it looks as though it is connected to a tap on the primary of the mains transformer. I would be grateful if anyone can confirm that, as there were and still are so many faults and bodges on this set I wouldn't be surprised if it was connected incorrectly (or were my own notes from it's removal incorrect?)
Anyway, any information or thoughts about getting the motor running appreciated. Looks as though I will also need to find or rewind the pick up coil, and I begin to wonder how if this is too far gone to bother.
Tony
Attached Thumbnails
Click image for larger version

Name:	P1130551.jpg
Views:	142
Size:	71.8 KB
ID:	207020   Click image for larger version

Name:	P1130552.jpg
Views:	137
Size:	66.6 KB
ID:	207021   Click image for larger version

Name:	P1130553.jpg
Views:	124
Size:	67.1 KB
ID:	207022  
greenstar is offline  
Old 28th May 2020, 2:20 pm   #2
Trigon.
Hexode
 
Trigon.'s Avatar
 
Join Date: Jun 2018
Location: Buckinghamshire, UK.
Posts: 382
Default Re: Motor and its capacitor on HMV Q286 radiogram, 1934.

There are some interesting photos in the link below -

https://forum.talkingmachine.info/vi...hp?f=9&t=37901

- which appear to show two rectangular components as compared to your single one?

Click image for larger version

Name:	hmv.jpg
Views:	102
Size:	158.6 KB
ID:	207033

Cheers
Trigon. is online now  
Old 28th May 2020, 3:01 pm   #3
greenstar
Octode
 
greenstar's Avatar
 
Join Date: Jul 2011
Location: Leicester, Leics. UK.
Posts: 1,681
Default Re: Motor and its capacitor on HMV Q286 radiogram, 1934.

That is interesting. However, there is no sign of there having been a second capacitor on this one. Of course this is a possibility given the one you mention. It is certainly a similar motor. Generally induction motors seem to have one capacitor. What sort of value, what type, and polarity if electrolytic, would be helpful to know?
Attached Thumbnails
Click image for larger version

Name:	P1130554.jpg
Views:	73
Size:	66.4 KB
ID:	207034   Click image for larger version

Name:	P1130555.jpg
Views:	60
Size:	74.1 KB
ID:	207035  
greenstar is offline  
Old 28th May 2020, 5:25 pm   #4
greenstar
Octode
 
greenstar's Avatar
 
Join Date: Jul 2011
Location: Leicester, Leics. UK.
Posts: 1,681
Default Re: Motor and its capacitor on HMV Q286 radiogram, 1934.

This one looks to have two capacitors - if that is what they are - as well.
https://www.youtube.com/watch?v=tW6eIU3hSIU
Attached Thumbnails
Click image for larger version

Name:	Screenshot from 2020-05-28 17-24-49.jpg
Views:	81
Size:	46.8 KB
ID:	207049  
greenstar is offline  
Old 28th May 2020, 5:28 pm   #5
snowman_al
Octode
 
snowman_al's Avatar
 
Join Date: Dec 2018
Location: Llandeilo, West Wales, UK.
Posts: 1,092
Default Re: Motor and its capacitor on HMV Q286 radiogram, 1934.

I assume the disc is really free spinning with no power applied?
Then with power on does the disc spin if you 'give it a hand'?
Again with power on, does the disc feel 'locked' or coggy?
I would also assume you need at least a 20uF cap if that is what the original measures. As it works on AC you need non polarised caps. (Though back to back electrolytics might work if you double their capacity).
__________________
Never Leave Well Enough Alone...
snowman_al is offline  
Old 28th May 2020, 6:54 pm   #6
greenstar
Octode
 
greenstar's Avatar
 
Join Date: Jul 2011
Location: Leicester, Leics. UK.
Posts: 1,681
Default Re: Motor and its capacitor on HMV Q286 radiogram, 1934.

Thanks Snowman. Can I assume this is a 220v motor? I had no idea 20uf non polarised caps existed for mains, especially in the 30's, but it's worth a try. I wouldn't mind being sure about that, as looking on ebay they are not cheap. I will check out your pointers tomorrow.
greenstar is offline  
Old 28th May 2020, 7:44 pm   #7
Michael Maurice
Moderator
 
Michael Maurice's Avatar
 
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,219
Default Re: Motor and its capacitor on HMV Q286 radiogram, 1934.

What type of deck is it? Can you post a picture of the top of the deck?
__________________
Forum Moderator

http://www.michaelmauricerepairs.co.uk/
Michael Maurice is online now  
Old 28th May 2020, 8:13 pm   #8
greenstar
Octode
 
greenstar's Avatar
 
Join Date: Jul 2011
Location: Leicester, Leics. UK.
Posts: 1,681
Default Re: Motor and its capacitor on HMV Q286 radiogram, 1934.

Here is the deck from above.
Attached Thumbnails
Click image for larger version

Name:	P1130556.jpg
Views:	94
Size:	66.1 KB
ID:	207061   Click image for larger version

Name:	P1130557.jpg
Views:	79
Size:	69.2 KB
ID:	207062  
greenstar is offline  
Old 28th May 2020, 9:18 pm   #9
greenstar
Octode
 
greenstar's Avatar
 
Join Date: Jul 2011
Location: Leicester, Leics. UK.
Posts: 1,681
Default Re: Motor and its capacitor on HMV Q286 radiogram, 1934.

I have just powered it up to check Snowman's points. To do so I firstly checked the voltage on the transformer tap I thought was used for the deck, which I couldn't get an ac reading on. I then transferred to the mains in tab. Also I made sure the switch was connecting - I have suspected it not doing so at times. And it ran. So I am pleased and embarrassed to say that the motor does seem to be running. It is slightly fast by the looks of a speed tester, but not by a lot. Would the capacitor have an effect on speed?
Tony
greenstar is offline  
Old 28th May 2020, 9:21 pm   #10
peter_sol
Octode
 
Join Date: Aug 2003
Location: Welwyn Garden City, Herts. UK.
Posts: 1,906
Default Re: Motor and its capacitor on HMV Q286 radiogram, 1934.

The 2 capacitors may have been connected in series.
peter_sol is offline  
Old 28th May 2020, 11:33 pm   #11
Michael Maurice
Moderator
 
Michael Maurice's Avatar
 
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,219
Default Re: Motor and its capacitor on HMV Q286 radiogram, 1934.

Or parallel.

You can find some information here and here
__________________
Forum Moderator

http://www.michaelmauricerepairs.co.uk/
Michael Maurice is online now  
Old 29th May 2020, 10:17 am   #12
gramofiend
Pentode
 
Join Date: Aug 2010
Location: Cowbridge, Vale of Glamorgan, UK.
Posts: 137
Default Re: Motor and its capacitor on HMV Q286 radiogram, 1934.

If the motor is running slightly fast only, then check that with the blunderbus pick up tracking the record that the speed may be correct. I have one of these in a similar HMV radiogram and it puzzled me for a while.

mike.
gramofiend is offline  
Old 29th May 2020, 10:23 am   #13
gramofiend
Pentode
 
Join Date: Aug 2010
Location: Cowbridge, Vale of Glamorgan, UK.
Posts: 137
Default Re: Motor and its capacitor on HMV Q286 radiogram, 1934.

Another thought too, in order to preserve records. Check the rubber damper on the needle armature is pliant. Velleman rubber wire sleeves can be useful for this. I have a Vidor wind up record player with a garrard pick up which plugs into electronics such as a radio, which I re built to very great effect.
Mike.
gramofiend is offline  
Old 29th May 2020, 11:27 am   #14
Herald1360
Dekatron
 
Herald1360's Avatar
 
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,527
Default Re: Motor and its capacitor on HMV Q286 radiogram, 1934.

Quote:
Originally Posted by gramofiend View Post
Another thought too, in order to preserve records. Check the rubber damper on the needle armature is pliant. Velleman rubber wire sleeves can be useful for this. I have a Vidor wind up record player with a garrard pick up which plugs into electronics such as a radio, which I re built to very great effect.
Mike.
Velleman?

Hellerman perhaps?
__________________
....__________
....|____||__|__\_____
.=.| _---\__|__|_---_|.
.........O..Chris....O
Herald1360 is offline  
Old 29th May 2020, 3:01 pm   #15
greenstar
Octode
 
greenstar's Avatar
 
Join Date: Jul 2011
Location: Leicester, Leics. UK.
Posts: 1,681
Default Re: Motor and its capacitor on HMV Q286 radiogram, 1934.

Just an update on this. Thanks to mod Michael especially for pointing me to the essential information. I will try to explain from my incomplete understanding.
It appears to be a type 24 AC HMV induction disc motor. (A similar motor, model 85 is shown with two condensers).
From the information on Paul Stenning's site, the 24AC can operate at various voltages. Three arrangements are given, for 100-130v, 130-160v, 200-250v AC. The 130-160v operation involves a single 3uF condenser in series with the power input. The other two options do not. This accords with the existence on the motor of a single condenser/capacitor. Also it does appear as I thought may be that the motor was connected to a tap in the mains transformer primary. That transformer does work and does give life to the chassis (which at the moment just lights up and hums). But i did not measure anything at that tap when I checked. Will do so again.
To check this I have just hooked the deck up to my variac and metered the ac volts supplied. With the condenser fitted it started rotating at 100v. At 160 it ran at close to 78rpm, measured with a strobe disc.
I do not understand why on a 220v AC set this was done, given that the motor has a 220v option! There must be a reason, but it escapes me. As I have discovered, it will run as it is, with condenser, on 220v. I now have the connection diagram to connect it to 220, with which it is not suggested fitting a condenser.
Could anybody explain to me,
1/Why this odd arrangement of running at 160v.
2/What the condenser does. As this is a brushless motor it would not seem to reduce interference.
3.Is there any reason I should not remove the condenser and run at 220 directly from the mains input?
4. Why there are no condensers-capacitors specified when running on the two other voltages.
(I could if acceptable put a scan of the relevant page here, although Paul is supplying the full document at a very modest cost).

Gramofiend, thanks, another conundrum is the pickup, which is open circuit. I may just leave this until I get the amp working.

(Before somebody says, I have previously restuffed the capacitor box, replaced numerous resistors, and replaced every paper cap I could see. Not to mention the drive cord, a valve holder and repair of another. The thing was in such a state I would not have dared connect to the mains before so doing)!

Last edited by greenstar; 29th May 2020 at 3:08 pm.
greenstar is offline  
Old 30th May 2020, 4:11 pm   #16
greenstar
Octode
 
greenstar's Avatar
 
Join Date: Jul 2011
Location: Leicester, Leics. UK.
Posts: 1,681
Default Re: Motor and its capacitor on HMV Q286 radiogram, 1934.

Just to note that with this motor, HMV Type 24, to change the working voltage not only should the capacitor be removed/added, but the position of the links on the terminal board needs changing.
greenstar is offline  
Old 31st May 2020, 10:46 am   #17
gramofiend
Pentode
 
Join Date: Aug 2010
Location: Cowbridge, Vale of Glamorgan, UK.
Posts: 137
Default Re: Motor and its capacitor on HMV Q286 radiogram, 1934.

Herald! Thanks for the correction. I had Velleman on the brain from a recent Kit build. Have only just turned 70 but do wonder what lies ahead!!

Mike
gramofiend is offline  
Old 31st May 2020, 4:11 pm   #18
greenstar
Octode
 
greenstar's Avatar
 
Join Date: Jul 2011
Location: Leicester, Leics. UK.
Posts: 1,681
Default Re: Motor and its capacitor on HMV Q286 radiogram, 1934.

Just to add.
I checked again whether the motor ran on the primary tap, and it did not, nor could I read any ac voltage on that tap. So I decided to try and see if it will run straight from the mains input.
The motor connections were slightly different to those on the service leaflet, and there is no connection strip as shown there, as you can see on post 3. I could not make much sense of it, but. The only difference in the arrangement for 130-160v and 200-250v appeared to be the series capacitor at 130-160v, the link being shown in the same position for each. It moves for 100-130.
Therefore I connected the two leads to the same capacitor tag and connected the motor to the transformer primary mains in terminals. Fitting it all back together I find it runs well, and speed is exactly 78rpm as set on my variac at 160v. That is a little slower than with the cap fitted. The only thing noticeable was a little hum from the motor, which is not noticeable with the lid down. Maybe that was why a lower voltage was used. So for the moment, unless illumination strikes, I will take this as a satisfactory solution. Thanks all for your help and suggestions.
greenstar is offline  
Old 31st May 2020, 6:48 pm   #19
Techman
Dekatron
 
Techman's Avatar
 
Join Date: Nov 2009
Location: Lincolnshire, UK.
Posts: 4,985
Default Re: Motor and its capacitor on HMV Q286 radiogram, 1934.

I came across this with an old Columbia radiogram that I did some work on for someone a few years ago. The gram motor wasn't normal mains voltage, but something like 200 volts, I can't remember exactly, and it ran from the 200 volt tapping of the mains transformer primary, using it as an 'auto-transformer' for the motor supply. I think this was done because there were such large variations in regional mains voltages, that the end user would need to set the mains tapping in just one simple move at the mains transformer only, rather than having to mess about with settings on the motor as well, which would have been awkward. I wouldn't have noticed this normally and I've probably worked on others with a similar setup and never noticed, except that this one had a burnt out primary winding on the mains transformer, so I had to replace it. Therefore I would strongly advise double checking whether the motor is happy to run on full mains and also why the proper tapping on the transformer isn't working - it could possibly be like the one that I worked on with a partially damaged primary, although on that particular one the transformer was absolutely burnt out on that section.
Techman is offline  
Old 31st May 2020, 7:09 pm   #20
greenstar
Octode
 
greenstar's Avatar
 
Join Date: Jul 2011
Location: Leicester, Leics. UK.
Posts: 1,681
Default Re: Motor and its capacitor on HMV Q286 radiogram, 1934.

Hi Techman, I will attach a figure from the information leaflet available from Paul. This shows the same Type 24 motor set up for various voltages. I can only go by that. The chassis is certainly doing something, as the valves light up, and the set hums and there's a bit of motorboating on gram, so I am assuming the transformer is supplying ok. I will need to look at that next and see if I can get it working properly, but have recapped etc. I don't know what voltage the tapping is supposed to supply - it is simply marked 'C' on transformer and schematic, and no further info is there.
Attached Thumbnails
Click image for larger version

Name:	Screenshot from 2020-05-31 19-01-48.jpg
Views:	63
Size:	64.4 KB
ID:	207320  
greenstar is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 10:15 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.