Creek 4140 S2 repair - UK Vintage Radio Repair and Restoration Discussion Forum

rajembt · 1st Mar 2018, 3:17 am

I am currently trying to repair a recently acquired Creek 4140 S2 which has had some strange modifications done on the phono stage.

It sounds thin, as if there is no RIAA equalisation taking place. The line inputs are fine, so the power amp stage must be OK.

On the schematic, there is a missing value for an electrolytic capacitor (marked in a circle on the pdf). Does anyone know what that should be?

On my circuit board the capacitors are missing (one for each channel) - I have arrowed on the picture where they should be - adjacent to the 25V 47uF capacitors.

Perhaps if someone could look at their board and tell me the value it would be much appreciated.

Thanks

crackle · 1st Mar 2018, 6:00 pm

I assume that MM stands for Moving Magnet, if that capacitor is missing then there will be no throughput from the MM circuit RIAA stage to the Line preamp stage, I am surprised the disc function is working at all.
10uF 50v is what is used on the other stages as the DC blocking cap.

Mike

Radio Wrangler · 1st Mar 2018, 6:45 pm

There may be some connections added so the mod bypasses the RIAA equalisation stage so the record playing input can be used with an external MC/MM equaliser box.

David

rajembt · 2nd Mar 2018, 1:09 am

That seems to be the case David, as I noted some long wires on the underneath of the board connecting the RCA phono inputs to the phono selector button. I am guessing this more or less converted it into another line input.

Someone did suggest using a value of under 1uF to roll of some of the low frequency since the signal is coming from the phone preamp. He said a 0.15uF would give a roll off at about 10Hz.

1st Mar 2018, 6:00 pm	#2
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	Re: Creek 4140 S2 repair I assume that MM stands for Moving Magnet, if that capacitor is missing then there will be no throughput from the MM circuit RIAA stage to the Line preamp stage, I am surprised the disc function is working at all. 10uF 50v is what is used on the other stages as the DC blocking cap. Mike Last edited by crackle; 1st Mar 2018 at 6:08 pm.

1st Mar 2018, 6:45 pm	#3
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,902	Re: Creek 4140 S2 repair There may be some connections added so the mod bypasses the RIAA equalisation stage so the record playing input can be used with an external MC/MM equaliser box. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

2nd Mar 2018, 1:09 am	#4
rajembt Retired Dormant Member Join Date: Mar 2018 Location: Maidenhead, Berkshire, UK. Posts: 2	Re: Creek 4140 S2 repair That seems to be the case David, as I noted some long wires on the underneath of the board connecting the RCA phono inputs to the phono selector button. I am guessing this more or less converted it into another line input. Someone did suggest using a value of under 1uF to roll of some of the low frequency since the signal is coming from the phone preamp. He said a 0.15uF would give a roll off at about 10Hz.