Bush SRP51 Treble control problem

[leslie5555]

Treble control not working, so I cleaned it with servisol and still not working so I checked the resistance and it seems to be working fine ranging from zero up to 5.88 this picture is of what I think is a capacitor connected to the treble control pot and on the service sheet it says C6 which says its 330Kpf.
The lettering on the back is
0.33/20//250
341 44334 SA/1
Can someone confirm that this is a capacitor and if so what value can I replace it with? I am not familiar with Kpf I am used to working with UF
Cheers Les

[music-centre]

Hello Les,
Yes, looks like a 0.33uF / 330,000Pf / 330nF Capacitor
Steve.

[Herald1360]

KpF = nF or even mμF (in the spirit of μμF = pF)

[leslie5555]

Ok thank you both for your replies, but I am a little confused as the component markings says 0.33 but the service sheet says 330Kpf
So is that 330nf or 0.330nf??
Or am I looking at the wrong component (C6) on the service sheet (I am not very experienced with reading circuit diagrams)

[TonyDuell]

It's 330nF.

The capacitor is marked in microfarads (uF). 0.33uF = 330nF. It's also the same as 330000pF, which is the 330KpF (K=1000) on the service sheet.

[peter_sol]

Although it is unlikely to be at fault.

[Herald1360]

Did you check the pot from both ends to wiper?

Should read zero all the time from one end to wiper and 0-5k-ish from the other when in circuit.

If that's OK, try the cap by adding pretty much anything from 100n to 1u across it- if there is now some effect then unlikely though it is, the cap is faulty.

[AC/HL]

There are plenty of conversion charts on the web if you're unsure.
Here's a fairly comprehensive one: https://www.instructables.com/id/HOW...APACITOR-VALU/

[ms660]

Originally Posted by leslie5555

The lettering on the back is
0.33/20//250
341 44334 SA/1
Can someone confirm that this is a capacitor and if so what value can I replace it with? I am not familiar with Kpf I am used to working with UF
Cheers Les

0.33uF/+-20%//250Volts DC

https://www.cricklewoodelectronics.com/CPE330N.html

Other suppliers are available.

Lawrence.

[leslie5555]

Thanks again for all your brilliant help.
Now I know what the capacitors value is I checked it with a capacitor meter and it measured spot on,
And I rechecked the pot in the way that Chris explained and that checks out OK as well.
So I put it back together then tested it and it's not working.
So I am stumped as what to do next, any ideas anyone?

[ms660]

Check the treble circuit's continuity.

Lawrence.

[leslie5555]

Thanks Lawrence I will try that tomorrow.

[Herald1360]

Yes, a bad connection at either end of the capacitor would make the treble control ineffective without breaking the signal path.

[leslie5555]

I have checked continuity and all seems well I posted a pic of the pot connections does that look correct I think someone has been in here before.

[Herald1360]

It's not very clear,but it looks like someone may have connected the signal wires to the pot incorrectly.

If you have the circuit for reference, I'd disconnect everything from the pot and start again ensuring that all connections go to where they should. If that means an extra wire somewhere, then add it!

You need:

Connection from RV2 C5 end not connected to wiper to RV3 end linked to wiper.
Connection from RV3 end linked to wiper via TP4 to C7+.
C6 then connects between the other end of RV3 and 0V/ground.

[leslie5555]

The left tag has two white wires connected to it the center and right are connected to the capacitor

[Nuvistor]

Circuit snip. RV3 is treble.

[leslie5555]

thanks Chris for explaining where connections should go .
unfortunately I am not good at reading circuit diagrams.
Maybe you could explain where they go via the pictures I have taken.
Les

[ms660]

If one of the white leads that's connected to the treble pot is connected to the bass pot I would say it's wired correctly.

If the pot isn't duff, make sure that there is continuity between the ground end of the 0.33uF capacitor (the end that's connected to the chassis the pots mounted on) and the PCB's -ve (ground) rail.

Also can we assume that there is plenty of treble when a record is playing with this fault?

Lawrence.

[Nuvistor]

There is a blue electrolytic capacitor in the third photo that appears to have leaked. Have you checked it, if it has leaked it needs replacing. Probably nothing to do with the treble control.