HMV 2403 noise and no signal in RH channel - UK Vintage Radio Repair and Restoration Discussion Forum

RojDW48 · 17th Apr 2018, 8:13 pm

I got this from an antique shop thinking the problem was a dirty pot - sadly not. The RH channel is very noisy with no signal getting through, LH is fine. Has anyone experience of one of these and its likely fault?

Nuvistor · 17th Apr 2018, 8:34 pm

I have no experience of the player.

The circuit shows that the input from the cartridge can be switched to mono, is there no output from the RH channel when in mono?
Worthwhile cleaning the switches.

There are only 5 transistors in each channel so if the fault is in the amp there is not a lot to check.

Circuit available from the service data.
https://www.service-data.com/section.php/3835/1/2403

RojDW48 · 17th Apr 2018, 11:24 pm

Thank you Frank - I have bought the schematic but I am a complete novice when it comes to solid state circuitry (I knew it was and I should not have been tempted, but it was such a neat little player). Yes I get signal out of the RH channel on mono but the same awful noise as well. There is a 5 pin 180 DIN socket for (I assume) tape but it appears to be stone dead. The 'radio' input appears to be an RF socket, which probably dates it to pre-stereo broadcast radio. I shall peer at the circuit diagram and see if I can make sense of it.

Nuvistor · 18th Apr 2018, 12:03 am

Does the volume control affect the noise on the RH channel?

If the RH channel works in mono but not in stereo at least shows there is no input from the cartridge circuit, possibly cartridge, wiring or switch, the noise could be either from this area or something in the amplifier.

With a bit of luck the lack of RH and the noise will be the same problem.

The DIN socket is for record or playback, just use the correct connections shown in the circuit. The radio input is mono.

Michael Maurice · 18th Apr 2018, 8:43 am

Unfortunately the service sheet doesn't give transistor types but you might find that TR1/2 is the culprit.

In that position and in that position only, you can substitute a silicon transistor ie BC548 instead of the germanium type.

RojDW48 · 18th Apr 2018, 11:54 pm

Thank you Michael - that's hopeful. I have cleaned all the contacts and, whatever else is going on, there is something very unstable happening in the RH channel. I shall report back.

Grubhead · 20th Apr 2018, 8:59 pm

Stereo amps are just mono amps doubled. Compare the left channel with the bad channel and the solution will present itself.
You can buzz check each channel, since it's a transistor set. An insulated screwdriver touching the amp ONLY parts will cause a buzz. Compare that with the good channel and you should find what is playing up.

17th Apr 2018, 8:13 pm	#1
RojDW48 Nonode Join Date: Jun 2014 Location: Bristol, UK. Posts: 2,074	HMV 2403 noise and no signal in RH channel I got this from an antique shop thinking the problem was a dirty pot - sadly not. The RH channel is very noisy with no signal getting through, LH is fine. Has anyone experience of one of these and its likely fault? Attached Thumbnails __________________ '....don't go mistaking Paradise for that home across the road!' (Bob Dylan)

17th Apr 2018, 8:34 pm	#2
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: HMV 2403 noise and no signal in RH channel I have no experience of the player. The circuit shows that the input from the cartridge can be switched to mono, is there no output from the RH channel when in mono? Worthwhile cleaning the switches. There are only 5 transistors in each channel so if the fault is in the amp there is not a lot to check. Circuit available from the service data. https://www.service-data.com/section.php/3835/1/2403 __________________ Frank

17th Apr 2018, 11:24 pm	#3
RojDW48 Nonode Join Date: Jun 2014 Location: Bristol, UK. Posts: 2,074	Re: HMV 2403 noise and no signal in RH channel Thank you Frank - I have bought the schematic but I am a complete novice when it comes to solid state circuitry (I knew it was and I should not have been tempted, but it was such a neat little player). Yes I get signal out of the RH channel on mono but the same awful noise as well. There is a 5 pin 180 DIN socket for (I assume) tape but it appears to be stone dead. The 'radio' input appears to be an RF socket, which probably dates it to pre-stereo broadcast radio. I shall peer at the circuit diagram and see if I can make sense of it. __________________ '....don't go mistaking Paradise for that home across the road!' (Bob Dylan)

18th Apr 2018, 12:03 am	#4
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: HMV 2403 noise and no signal in RH channel Does the volume control affect the noise on the RH channel? If the RH channel works in mono but not in stereo at least shows there is no input from the cartridge circuit, possibly cartridge, wiring or switch, the noise could be either from this area or something in the amplifier. With a bit of luck the lack of RH and the noise will be the same problem. The DIN socket is for record or playback, just use the correct connections shown in the circuit. The radio input is mono. __________________ Frank

18th Apr 2018, 8:43 am	#5
Michael Maurice Moderator Join Date: Feb 2006 Location: Wembley, Middlesex Posts: 7,224	Re: HMV 2403 noise and no signal in RH channel Unfortunately the service sheet doesn't give transistor types but you might find that TR1/2 is the culprit. In that position and in that position only, you can substitute a silicon transistor ie BC548 instead of the germanium type. __________________ Forum Moderator http://www.michaelmauricerepairs.co.uk/

18th Apr 2018, 11:54 pm	#6
RojDW48 Nonode Join Date: Jun 2014 Location: Bristol, UK. Posts: 2,074	Re: HMV 2403 noise and no signal in RH channel Thank you Michael - that's hopeful. I have cleaned all the contacts and, whatever else is going on, there is something very unstable happening in the RH channel. I shall report back. __________________ '....don't go mistaking Paradise for that home across the road!' (Bob Dylan)

20th Apr 2018, 8:59 pm	#7
Grubhead Heptode Join Date: Dec 2016 Location: Sheffield, South Yorkshire, UK. Posts: 539	Re: HMV 2403 noise and no signal in RH channel Stereo amps are just mono amps doubled. Compare the left channel with the bad channel and the solution will present itself. You can buzz check each channel, since it's a transistor set. An insulated screwdriver touching the amp ONLY parts will cause a buzz. Compare that with the good channel and you should find what is playing up.