1957 PORTLAND record player - UK Vintage Radio Repair and Restoration Discussion Forum

112stereo · 1st Dec 2018, 2:38 pm

Guess what another virtually unknown record player I have been asked to look at. I know I'm old but 1957? I didn't have a record player till 1965. Sorry I digress.
A friend has just bought, don't ask me why, a 1957 PORTLAND record player originally sold by Currys.
The previous owner has clearly done some work on it including replacing the smoothing caps for single ones, I presume the original was in a metal can like most amps.
The player works with a reasonable amount of volume, but there is a constant mains hum which can be heard behind the music. It is constant no matter what the volume level is, at maximum volume it can barely be heard but on quiet passages it is there.
I have checked the chassis earth connections all appear ok .
I have to presume the previous owner has fitted the right value caps and not just fitted a couple he had in stock, but without a circuit diagram I can't be sure.
Anyone out there have any clues please.
It has a mains transformer and a two core mains cable which it started it's life with.
I eagerly awaite any thoughts.

By the way if anyone offered advice on my previous thread the HF29 it has gone to a museum just for show. At least it wasn't scrapped.

Techman · 1st Dec 2018, 2:48 pm

Looks like someone has fitted a new mains lead and possibly the mains wiring on the amplifier side of the switch too. Look how close that mains wire is to the volume slider connection wire - mains hum regardless of volume control heaven!

'LIVEWIRE?' · 1st Dec 2018, 2:51 pm

I would have thought that 2 x 33uf was quite adequate for reservoir & smoothing caps. provided the ripple current rating of the new caps. was adequate, and that they have been correctly fitted, particularly with regard to bridging any earth connections original joined via the metal case of the original.

G8UWM-MildMartin · 1st Dec 2018, 3:32 pm

Looks like it has a UL41 valve. They are prone to developing internal leakage. There are posts on testing them and how to cure them using gas cooker ignition sparks, if necessary.

112stereo · 1st Dec 2018, 4:25 pm

Thank you I shall look into those points..
The caps appear to be fitted correctly and the negative side is soldered to the chassis not sure how to determine their ripple value.
I was beginning to wonder about the valve, can't hurt trying what you suggest.

112stereo · 1st Dec 2018, 4:46 pm

The valve leakage certainly seems to be an issue with these valves looking at the posts on this site.
How do think about leaving the uy41 in , but using a rectifying diode to do the job leaving the uy41 redundant just running the heaters ? I might have to change the coupling resistor to a higher value !

Nuvistor · 1st Dec 2018, 5:06 pm

If the UY41 is working you may as well leave it, simple voltage check would confirm if it was good.

The UL41 needs checking for the hum and possibly grid current.

112stereo · 2nd Dec 2018, 10:15 am

Unfortunately the uy41 is the fault. A friend came over last night with a record player that uses the same pair of valves, we swapped them over and the fault swapped over so that's pretty conclusive.
I am not confident enough to try and salvage the valve through the suggestions on this site.
I just need to decide do I spend around £10 on another valve or do I scrap the valve and fit a semi-conductor one for £1.99 instead, after all some models use them already.
Once again thanks guys.

Herald1360 · 2nd Dec 2018, 11:45 am

Do you mean UL41?

112stereo · 2nd Dec 2018, 12:43 pm

Yes sorry.

Herald1360 · 2nd Dec 2018, 2:57 pm

If you're up for modifications, a UL84 or even UCL82 could be used with attention to biassing requirements. Even a UCL83 with a series heater resistor as well.

PaulR · 2nd Dec 2018, 3:00 pm

The semiconductor solution was for the UY41 rectifier not the UL41 output valve. I have found that the later CV1977 replacements are more reliable than the original valves but take ages to heat up, presumably because of improved heater/cathode insulation.

112stereo · 2nd Dec 2018, 3:08 pm

Thanks that's something I will need to decide on, which avenue to go down.

ben · 3rd Dec 2018, 12:45 am

A tenner to solve the problem at a stroke, and make a nice looking player like this useable again whilst keeping it original? It's a no-brainer to me!

112stereo · 3rd Dec 2018, 4:32 pm

Thank you.
I have just purchased an equivalent it seemed the better option.

PaulR · 3rd Dec 2018, 5:48 pm

Good, in a record player that won't get hours of continual use every day it should last a very long time.

112stereo · 5th Dec 2018, 5:48 pm

I purchased a pair of valves for this player, it has had a significant effect on the hum, but it is still quite noticeable when no music is played, but the volume control has no effect on the level of hum.
I appreciate these amps are cheaply made but is there something I can do to reduce it a bit?
Someone said try running the heaters on dc using a half wave rectifier, is this possable ?
This is just a hypothetical question, I won't do on this amp but might try it, if practical, on another valve amp I use most days which has a slight mains hum.

Edward Huggins · 5th Dec 2018, 7:06 pm

The amp already uses half wave rectification (UY41). Hum, when volume is at minimum, usually suggests poor smoothing and reservoir caps. Although I see that there are newer replacements fitted, they may have become faulty over time.

Sideband · 5th Dec 2018, 8:43 pm

That wiring to the switch needs attention....very badly done and the mains lead wiring is far too close to the volume control tags (as alluded to in post 2). Basically what you need to do is reposition the mains connections to the switch as far away from the volume control section as possible. The blue and yellow wires look as if they are almost touching the green wire from the volume control centre tag.....that's 50Hz of hum being closely coupled into the grid of the UL41. Either try moving the green wire or the blue and yellow wires. Then the brown and blue wires....again too close to the blue wire connecting to the outer tag of the volume control.

Techman · 6th Dec 2018, 2:08 am

Quote:

Originally Posted by Sideband

That wiring to the switch needs attention....

Exactly!

This is what I told you immediately after your very first post on this thread in post #2, and as mentioned by 'Sideband' above, but you didn't seem to take on board my advice

The first thing to do is to carefully move the signal and mains wire away from each other and see if you notice any slight difference. If you do, then re-do the wiring properly as said above.

1st Dec 2018, 2:38 pm	#1
112stereo Pentode Join Date: Jan 2014 Location: St Albans, Hertfordshire, UK. Posts: 215	1957 PORTLAND record player Guess what another virtually unknown record player I have been asked to look at. I know I'm old but 1957? I didn't have a record player till 1965. Sorry I digress. A friend has just bought, don't ask me why, a 1957 PORTLAND record player originally sold by Currys. The previous owner has clearly done some work on it including replacing the smoothing caps for single ones, I presume the original was in a metal can like most amps. The player works with a reasonable amount of volume, but there is a constant mains hum which can be heard behind the music. It is constant no matter what the volume level is, at maximum volume it can barely be heard but on quiet passages it is there. I have checked the chassis earth connections all appear ok . I have to presume the previous owner has fitted the right value caps and not just fitted a couple he had in stock, but without a circuit diagram I can't be sure. Anyone out there have any clues please. It has a mains transformer and a two core mains cable which it started it's life with. I eagerly awaite any thoughts. By the way if anyone offered advice on my previous thread the HF29 it has gone to a museum just for show. At least it wasn't scrapped. Attached Thumbnails

1st Dec 2018, 2:51 pm	#3
'LIVEWIRE?' Rest in Peace Join Date: Mar 2006 Location: N.W. Oxfordshire(Chipping Norton) Posts: 7,306	Re: 1957 PORTLAND record player I would have thought that 2 x 33uf was quite adequate for reservoir & smoothing caps. provided the ripple current rating of the new caps. was adequate, and that they have been correctly fitted, particularly with regard to bridging any earth connections original joined via the metal case of the original.

1st Dec 2018, 3:32 pm	#4
G8UWM-MildMartin Heptode Join Date: Jan 2004 Location: Stockport, Greater Manchester, UK. Posts: 827	Re: 1957 PORTLAND record player Looks like it has a UL41 valve. They are prone to developing internal leakage. There are posts on testing them and how to cure them using gas cooker ignition sparks, if necessary.

1st Dec 2018, 4:25 pm	#5
112stereo Pentode Join Date: Jan 2014 Location: St Albans, Hertfordshire, UK. Posts: 215	Re: 1957 PORTLAND record player Thank you I shall look into those points.. The caps appear to be fitted correctly and the negative side is soldered to the chassis not sure how to determine their ripple value. I was beginning to wonder about the valve, can't hurt trying what you suggest.

1st Dec 2018, 4:46 pm	#6
112stereo Pentode Join Date: Jan 2014 Location: St Albans, Hertfordshire, UK. Posts: 215	Re: 1957 PORTLAND record player The valve leakage certainly seems to be an issue with these valves looking at the posts on this site. How do think about leaving the uy41 in , but using a rectifying diode to do the job leaving the uy41 redundant just running the heaters ? I might have to change the coupling resistor to a higher value !

1st Dec 2018, 2:48 pm	#2
Techman Dekatron Join Date: Nov 2009 Location: Lincolnshire, UK. Posts: 5,000	Re: 1957 PORTLAND record player Looks like someone has fitted a new mains lead and possibly the mains wiring on the amplifier side of the switch too. Look how close that mains wire is to the volume slider connection wire - mains hum regardless of volume control heaven!

1st Dec 2018, 5:06 pm	#7
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: 1957 PORTLAND record player If the UY41 is working you may as well leave it, simple voltage check would confirm if it was good. The UL41 needs checking for the hum and possibly grid current. __________________ Frank

2nd Dec 2018, 10:15 am	#8
112stereo Pentode Join Date: Jan 2014 Location: St Albans, Hertfordshire, UK. Posts: 215	Re: 1957 PORTLAND record player Unfortunately the uy41 is the fault. A friend came over last night with a record player that uses the same pair of valves, we swapped them over and the fault swapped over so that's pretty conclusive. I am not confident enough to try and salvage the valve through the suggestions on this site. I just need to decide do I spend around £10 on another valve or do I scrap the valve and fit a semi-conductor one for £1.99 instead, after all some models use them already. Once again thanks guys.

2nd Dec 2018, 11:45 am	#9
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: 1957 PORTLAND record player Do you mean UL41? __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

2nd Dec 2018, 12:43 pm	#10
112stereo Pentode Join Date: Jan 2014 Location: St Albans, Hertfordshire, UK. Posts: 215	Re: 1957 PORTLAND record player Yes sorry.

2nd Dec 2018, 2:57 pm	#11
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: 1957 PORTLAND record player If you're up for modifications, a UL84 or even UCL82 could be used with attention to biassing requirements. Even a UCL83 with a series heater resistor as well. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

2nd Dec 2018, 3:00 pm	#12
PaulR Dekatron Join Date: Oct 2003 Location: Southport Lancashire, UK. Posts: 3,233	Re: 1957 PORTLAND record player The semiconductor solution was for the UY41 rectifier not the UL41 output valve. I have found that the later CV1977 replacements are more reliable than the original valves but take ages to heat up, presumably because of improved heater/cathode insulation. __________________ Paul

2nd Dec 2018, 3:08 pm	#13
112stereo Pentode Join Date: Jan 2014 Location: St Albans, Hertfordshire, UK. Posts: 215	Re: 1957 PORTLAND record player Thanks that's something I will need to decide on, which avenue to go down.

3rd Dec 2018, 12:45 am	#14
ben Dekatron Join Date: Aug 2006 Location: Madrid, Spain / Wirral, UK Posts: 7,498	Re: 1957 PORTLAND record player A tenner to solve the problem at a stroke, and make a nice looking player like this useable again whilst keeping it original? It's a no-brainer to me! __________________ Regards, Ben.

3rd Dec 2018, 4:32 pm	#15
112stereo Pentode Join Date: Jan 2014 Location: St Albans, Hertfordshire, UK. Posts: 215	Re: 1957 PORTLAND record player Thank you. I have just purchased an equivalent it seemed the better option.

3rd Dec 2018, 5:48 pm	#16
PaulR Dekatron Join Date: Oct 2003 Location: Southport Lancashire, UK. Posts: 3,233	Re: 1957 PORTLAND record player Good, in a record player that won't get hours of continual use every day it should last a very long time. __________________ Paul

5th Dec 2018, 5:48 pm	#17
112stereo Pentode Join Date: Jan 2014 Location: St Albans, Hertfordshire, UK. Posts: 215	Re: 1957 PORTLAND record player I purchased a pair of valves for this player, it has had a significant effect on the hum, but it is still quite noticeable when no music is played, but the volume control has no effect on the level of hum. I appreciate these amps are cheaply made but is there something I can do to reduce it a bit? Someone said try running the heaters on dc using a half wave rectifier, is this possable ? This is just a hypothetical question, I won't do on this amp but might try it, if practical, on another valve amp I use most days which has a slight mains hum.

5th Dec 2018, 7:06 pm	#18
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,327	Re: 1957 PORTLAND record player The amp already uses half wave rectification (UY41). Hum, when volume is at minimum, usually suggests poor smoothing and reservoir caps. Although I see that there are newer replacements fitted, they may have become faulty over time. __________________ Edward.

5th Dec 2018, 8:43 pm	#19
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,571	Re: 1957 PORTLAND record player That wiring to the switch needs attention....very badly done and the mains lead wiring is far too close to the volume control tags (as alluded to in post 2). Basically what you need to do is reposition the mains connections to the switch as far away from the volume control section as possible. The blue and yellow wires look as if they are almost touching the green wire from the volume control centre tag.....that's 50Hz of hum being closely coupled into the grid of the UL41. Either try moving the green wire or the blue and yellow wires. Then the brown and blue wires....again too close to the blue wire connecting to the outer tag of the volume control. __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman.....