ITT KPO43 record player - UK Vintage Radio Repair and Restoration Discussion Forum

recordplayer · 9th Jun 2019, 11:40 pm

Hi , got one of these players and bass control has no effect at all - only cleaned the pots so far - looks like it's going to look deeper into this - anyone had same fault ?

AC/HL · 10th Jun 2019, 10:49 am

It's a fairly basic circuit, is it the same on both channels?
https://www.service-data.com/section.php/4021/1/kp043

recordplayer · 10th Jun 2019, 6:41 pm

No only on left channel - I'm going to swop some transistors from other channel - changed the electrolytics as they were we'll out of spec

Station X · 10th Jun 2019, 7:43 pm

Quote:

Originally Posted by recordplayer

I'm going to swop some transistors from other channel

In my opinion that's a very bad idea, you could end up with two duff channels.

Apart from that, the tone controls are passive and positioned in the circuit before any transistors.

recordplayer · 20th Jun 2019, 6:20 pm

Ordered some transistors for this player two of them appear to be leaky - let's hope it cures the fault

crackle · 21st Jun 2019, 5:13 pm

The tone controls on this record player are very basic. The bass control appears to rely on increasing the load on the cartridge to reduce the base. So it is never going to be as effective as a modern amplifier, it may also depend on what cartridge has been fitted.
In the case of this record player I believe it should be a BSR SX5M

"CIRCUIT DESCRIPTION
The signal from the cartridge passes first to the bass control Ra2/Ra19 which functions by resistively loading the capacitive source. The treble control cuts the high frequencies when the slider is towards the end of the control connected to Ra4/Ra21. The balance control Ra17 functions by progressively shorting the signal of one channel or the other to earth. The signal is applied to the volume control Ra5/Ra22 and is then fed to the input of TXa1/TXa5 which is high impedance. "

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Mike

9th Jun 2019, 11:40 pm	#1
recordplayer Pentode Join Date: May 2010 Location: Preston, Lancashire, UK. Posts: 156	ITT KPO43 record player Hi , got one of these players and bass control has no effect at all - only cleaned the pots so far - looks like it's going to look deeper into this - anyone had same fault ?

10th Jun 2019, 10:49 am	#2
AC/HL Dekatron Join Date: Nov 2003 Location: Heckmondwike, West Yorkshire, UK. Posts: 9,642	Re: ITT KPO43 record player It's a fairly basic circuit, is it the same on both channels? https://www.service-data.com/section.php/4021/1/kp043

10th Jun 2019, 6:41 pm	#3
recordplayer Pentode Join Date: May 2010 Location: Preston, Lancashire, UK. Posts: 156	Re: ITT KPO43 record player No only on left channel - I'm going to swop some transistors from other channel - changed the electrolytics as they were we'll out of spec

20th Jun 2019, 6:20 pm	#5
recordplayer Pentode Join Date: May 2010 Location: Preston, Lancashire, UK. Posts: 156	Re: ITT KPO43 record player Ordered some transistors for this player two of them appear to be leaky - let's hope it cures the fault

21st Jun 2019, 5:13 pm	#6
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	Re: ITT KPO43 record player The tone controls on this record player are very basic. The bass control appears to rely on increasing the load on the cartridge to reduce the base. So it is never going to be as effective as a modern amplifier, it may also depend on what cartridge has been fitted. In the case of this record player I believe it should be a BSR SX5M "CIRCUIT DESCRIPTION The signal from the cartridge passes first to the bass control Ra2/Ra19 which functions by resistively loading the capacitive source. The treble control cuts the high frequencies when the slider is towards the end of the control connected to Ra4/Ra21. The balance control Ra17 functions by progressively shorting the signal of one channel or the other to earth. The signal is applied to the volume control Ra5/Ra22 and is then fed to the input of TXa1/TXa5 which is high impedance. " Mike