Need help with Elpico RP590 portable TT - UK Vintage Radio Repair and Restoration Discussion Forum

Analogman · 13th Apr 2019, 7:21 pm

Hello,
Hope someone can help me to find the problem with this amp.
The Elpico rp590 is a portable record player with a BSR Ua14 changer and a very simple 3 watt amplifier using a pcl82 valve. I fell in love with the changer and after some cleaning and re-lubrication it is working like a charm. The arm is wired for stereo but it had a mono tc8m in it which is unfortunately dead. So the first question is what system can I replace it with that can also be used safely for stereo records? At the moment I have a stereo Ronette 105 in there, but I'm not sure if this has enough output.
The amp is another story. First I thought of just replacing it with a simple modern stereo amp, but then I decided to recap it and check how it sounds. I have replaced all the electrolytic caps and the paper tar ones and most of the resistors. I found a schematic and used that to check the wiring. Cleaned the 3 potentiometers and also replaced the selenium rectifier with a 1n4007 diode and 5 watt 180ohm resistor in series.
The unit was origanally powered with a 2 wire lead that had been cut probably because it had a British plug, so I replaced that with a 2 pronged euro plug.
I then powered it up with a current limiter light bulb in series and everything seemed okay ( bulb lit up then dimmed). When I started the turntable motor the bulb went a bit brighter but not much. So I plugged it in directly and started to test it. The amp had a considerable amount of hum which increased when the volume was turned up. The changer dropped the record and the arm placed daintily down on the record. But the output of the Ronette (which I had wired up in series, stereo to mono) seemed a bit weak, the volume control having an effect at the very beginning but then none what so ever, and I am not sure if I had wired it up properly, but being annoyed by the loud hum I decided to try to ground the ground by running a wire from ground (pick up) to ground earth (mains socket). At this point the house fuse blew and I was left in the dark.
So I pulled the amp out again and did some voltage measurements and got some puzzling results.
First I measured the chassis to earth (mains socket) and got about 38vac.
Then I turned the 2 pronged plug around in the socket (unfortunately the European plugs are multi- directional) and measured 112vac from chassis to earth! Turned it back around and measured the dc voltage after the diode (i think this was around 370vdc) and noticed that there is no voltage drop after the resistor nor is the resistor getting warm.
The primary side of the transformer measured to chassis has about 180vac on the brown wire, about 38vac on the yellow wire. The grey and blue wire run to the TT motor. The next pin is ground. The two red wires are the 16v filament tap. On the secondary side is the green wire (180vac) which runs to the diode, then the black wire bridged to the primary ground and running directly to the speaker transformer then speaker.
There was no 0.03mfd capacitor between mains and ground so I left that out and the only other change I made was switching the red and orange wire on the output transformer as it seemed to be the wrong way around.
Hope someone has a clue. Obviously I need to ground this with a 3 pronged earthed plug when it is wired up properly. Photos and schematic attached.

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Analogman · 13th Apr 2019, 7:24 pm

Photos of amp and amp plus output transformer and speaker

julie_m · 13th Apr 2019, 8:04 pm

If you are getting only a thin, scratchy sound, you might have miswired the cartridge. The positives are diagonally opposite their respective negatives on a Ronette 105. If you have wired them "back to back" then the signal from one will try to cancel out the other and you will end up with the difference between the two channels (i.e., only sounds meant to come out of one speaker but not the other), rather than the sum (i.e., all sounds meant to come out of either or both speakers).

It will probably help to get just the left-hand channel or just the right-hand channel connected for initial testing. When you know which two pairs of pins are the two signals, then you only need to try swapping one pair over to switch between "difference" and "sum".

Also, you might try wiring the two channels in parallel rather than series. Crystal cartridges are already very high-impedance sources, and even a 1MΩ volume control will be a bit on the low side for the two channels in series.

snowman_al · 13th Apr 2019, 9:09 pm

Quote:

Originally Posted by Analogman

The unit was origanally powered with a 2 wire lead that had been cut probably because it had a British plug, so I replaced that with a 2 pronged euro plug.
... I decided to try to ground the ground by running a wire from ground (pick up) to ground earth (mains socket). At this point the house fuse blew and I was left in the dark.
So I pulled the amp out again and did some voltage measurements and got some puzzling results.
First I measured the chassis to earth (mains socket) and got about 38vac.
Then I turned the 2 pronged plug around in the socket (unfortunately the European plugs are multi- directional) and measured 112vac from chassis to earth! Turned it back around and measured the dc voltage after the diode (i think this was around 370vdc) and noticed that there is no voltage drop after the resistor nor is the resistor getting warm.
The primary side of the transformer measured to chassis has about 180vac on the brown wire, about 38vac on the yellow wire. The grey and blue wire run to the TT motor. The next pin is ground. The two red wires are the 16v filament tap. On the secondary side is the green wire (180vac) which runs to the diode, then the black wire bridged to the primary ground and running directly to the speaker transformer then speaker.
There was no 0.03mfd capacitor between mains and ground so I left that out and the only other change I made was switching the red and orange wire on the output transformer as it seemed to be the wrong way around.
Hope someone has a clue. Obviously I need to ground this with a 3 pronged earthed plug when it is wired up properly.

That concerns me.
Please ensure the mains transformer secondaries (the filament and ht supplies) are NOT some how connected to the mains live or neutral.
Do a simple continuity test from the chassis to the mains plug pins for a start. There should be no connection...
Alan

Analogman · 23rd Apr 2019, 9:41 am

Thanks for the replies.
After thorough testing and measuring I have decided to leave the original wiring albeit without the 0.03 mfd death cap. The loud humming from before was due to the Ronette 105 being wired up incorrectly. in the end parallel wiring worked. I tried to isolate the amp chassis from the circuit but this lead to even more hum and since this circuit uses the ground as B- it was easier to leave it as it was. Since the amplifier is installed in the case and cannot be touched directly it should not be a hazard. The weird measurements from before may have been incorrect due to DMM. The Ronette is working well but I have read in many (older) forums that the BSR SC12H is a good replacement. Unfortunately these seem to be no longer available, so I was wondering what the actual (2019) consensus is out there about what is a good modern replacement system for old tc8m or equivalent cartridges, to play modern stereo records without damaging them.
Thanks!

Analogman · 23rd Apr 2019, 9:45 am

Oh yeah, I forgot to mention that there was no continuity between the chassis and mains, so no worries there. The chassis voltages are simply the B- from the circuit.
Cheers.

'LIVEWIRE?' · 23rd Apr 2019, 11:01 am

There is a ceramic cartridge (possibly incorrectly described as a magnetic cartridge) with a 'flipover' stylus, similar to the BSR SC11 or 12, on eBay at a reasonable price, though it comes without a mounting bracket. An alternative might be one of the cheap (around £2 each) Chinese cartridges- again they come without a mounting clip, and, because they only have a single stylus designed for microgroove records, are not practical if you intend to regularly play 78s. The output from these cartridges should be adequate for the 2-stage amplifier used in your Elpico RP590, which shouldn't need a SC12H to adequately drive it.

Edward Huggins · 23rd Apr 2019, 2:34 pm

The BSR X5M mono, stereo-compatibe, cartridge is the ideal replacement cartridge for your Elpico, but I have recommmend this so many time that UK stocks may now be exhasuted. Worth a last try! Edward

13th Apr 2019, 7:21 pm	#1
Analogman Retired Dormant Member Join Date: Mar 2013 Location: Vienna, Austria Posts: 18	Need help with Elpico RP590 portable TT Hello, Hope someone can help me to find the problem with this amp. The Elpico rp590 is a portable record player with a BSR Ua14 changer and a very simple 3 watt amplifier using a pcl82 valve. I fell in love with the changer and after some cleaning and re-lubrication it is working like a charm. The arm is wired for stereo but it had a mono tc8m in it which is unfortunately dead. So the first question is what system can I replace it with that can also be used safely for stereo records? At the moment I have a stereo Ronette 105 in there, but I'm not sure if this has enough output. The amp is another story. First I thought of just replacing it with a simple modern stereo amp, but then I decided to recap it and check how it sounds. I have replaced all the electrolytic caps and the paper tar ones and most of the resistors. I found a schematic and used that to check the wiring. Cleaned the 3 potentiometers and also replaced the selenium rectifier with a 1n4007 diode and 5 watt 180ohm resistor in series. The unit was origanally powered with a 2 wire lead that had been cut probably because it had a British plug, so I replaced that with a 2 pronged euro plug. I then powered it up with a current limiter light bulb in series and everything seemed okay ( bulb lit up then dimmed). When I started the turntable motor the bulb went a bit brighter but not much. So I plugged it in directly and started to test it. The amp had a considerable amount of hum which increased when the volume was turned up. The changer dropped the record and the arm placed daintily down on the record. But the output of the Ronette (which I had wired up in series, stereo to mono) seemed a bit weak, the volume control having an effect at the very beginning but then none what so ever, and I am not sure if I had wired it up properly, but being annoyed by the loud hum I decided to try to ground the ground by running a wire from ground (pick up) to ground earth (mains socket). At this point the house fuse blew and I was left in the dark. So I pulled the amp out again and did some voltage measurements and got some puzzling results. First I measured the chassis to earth (mains socket) and got about 38vac. Then I turned the 2 pronged plug around in the socket (unfortunately the European plugs are multi- directional) and measured 112vac from chassis to earth! Turned it back around and measured the dc voltage after the diode (i think this was around 370vdc) and noticed that there is no voltage drop after the resistor nor is the resistor getting warm. The primary side of the transformer measured to chassis has about 180vac on the brown wire, about 38vac on the yellow wire. The grey and blue wire run to the TT motor. The next pin is ground. The two red wires are the 16v filament tap. On the secondary side is the green wire (180vac) which runs to the diode, then the black wire bridged to the primary ground and running directly to the speaker transformer then speaker. There was no 0.03mfd capacitor between mains and ground so I left that out and the only other change I made was switching the red and orange wire on the output transformer as it seemed to be the wrong way around. Hope someone has a clue. Obviously I need to ground this with a 3 pronged earthed plug when it is wired up properly. Photos and schematic attached.

13th Apr 2019, 7:24 pm	#2
Analogman Retired Dormant Member Join Date: Mar 2013 Location: Vienna, Austria Posts: 18	Re: Need help with Elpico RP590 portable TT Photos of amp and amp plus output transformer and speaker Attached Thumbnails

13th Apr 2019, 8:04 pm	#3
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Need help with Elpico RP590 portable TT If you are getting only a thin, scratchy sound, you might have miswired the cartridge. The positives are diagonally opposite their respective negatives on a Ronette 105. If you have wired them "back to back" then the signal from one will try to cancel out the other and you will end up with the difference between the two channels (i.e., only sounds meant to come out of one speaker but not the other), rather than the sum (i.e., all sounds meant to come out of either or both speakers). It will probably help to get just the left-hand channel or just the right-hand channel connected for initial testing. When you know which two pairs of pins are the two signals, then you only need to try swapping one pair over to switch between "difference" and "sum". Also, you might try wiring the two channels in parallel rather than series. Crystal cartridges are already very high-impedance sources, and even a 1MΩ volume control will be a bit on the low side for the two channels in series. __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

23rd Apr 2019, 9:41 am	#5
Analogman Retired Dormant Member Join Date: Mar 2013 Location: Vienna, Austria Posts: 18	Re: Need help with Elpico RP590 portable TT Thanks for the replies. After thorough testing and measuring I have decided to leave the original wiring albeit without the 0.03 mfd death cap. The loud humming from before was due to the Ronette 105 being wired up incorrectly. in the end parallel wiring worked. I tried to isolate the amp chassis from the circuit but this lead to even more hum and since this circuit uses the ground as B- it was easier to leave it as it was. Since the amplifier is installed in the case and cannot be touched directly it should not be a hazard. The weird measurements from before may have been incorrect due to DMM. The Ronette is working well but I have read in many (older) forums that the BSR SC12H is a good replacement. Unfortunately these seem to be no longer available, so I was wondering what the actual (2019) consensus is out there about what is a good modern replacement system for old tc8m or equivalent cartridges, to play modern stereo records without damaging them. Thanks!

23rd Apr 2019, 9:45 am	#6
Analogman Retired Dormant Member Join Date: Mar 2013 Location: Vienna, Austria Posts: 18	Re: Need help with Elpico RP590 portable TT Oh yeah, I forgot to mention that there was no continuity between the chassis and mains, so no worries there. The chassis voltages are simply the B- from the circuit. Cheers.

23rd Apr 2019, 11:01 am	#7
'LIVEWIRE?' Rest in Peace Join Date: Mar 2006 Location: N.W. Oxfordshire(Chipping Norton) Posts: 7,306	Re: Need help with Elpico RP590 portable TT There is a ceramic cartridge (possibly incorrectly described as a magnetic cartridge) with a 'flipover' stylus, similar to the BSR SC11 or 12, on eBay at a reasonable price, though it comes without a mounting bracket. An alternative might be one of the cheap (around £2 each) Chinese cartridges- again they come without a mounting clip, and, because they only have a single stylus designed for microgroove records, are not practical if you intend to regularly play 78s. The output from these cartridges should be adequate for the 2-stage amplifier used in your Elpico RP590, which shouldn't need a SC12H to adequately drive it.

23rd Apr 2019, 2:34 pm	#8
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,326	Re: Need help with Elpico RP590 portable TT The BSR X5M mono, stereo-compatibe, cartridge is the ideal replacement cartridge for your Elpico, but I have recommmend this so many time that UK stocks may now be exhasuted. Worth a last try! Edward __________________ Edward.