Wad step ups

[Bizzie]

I fired up my phonoII today to find that I only had the left channel working and a low hum from the right after swapping cables around isolated it to the right channel.

As some of you may remember from the wad bb I have fitted my phonoII with switchinge between MM and MC cartridges so when it worked perfectly with a MM cartridge I started to investigate the wiring and switching first and could find no problem as I don't have the time to unsolder anything I have checked the step up windings and both measure the same onthe input @ 1.4R the out put is a different matter the secondries measure 0.6R left channel(working channel) and 134.5R on the right channel.

It looks like there is a problem with the output coils although I would need to completely disconnect them to be sure, if the coils have developed a fault would it be just bad luck or could some other problem have caused the fault to develop.

[John Caswell]

Hi Bizzie,
Oh dear, on the face of it you have a u/s step up tx, but you need to disconnect them both to compare, rather than measure them in circuit.
I am surpised that the ratio of the working one is 1.4R to .6R as it is a step up device so I would expect a higher R on the secondary.

John aka Dr John

[Bizzie]

Yes I thought that should be the case but I haven't had the time to desolder them today but that must be because they are in curuit, but because there is a big difference I would think it shouldn't be too hard to trace if it doesn't turn out to be the stepups.

If it is the step ups I just hope that it was faulty and not caused by something else.

I have noticed that the right channel was quieter lately but thought that one of the valves may have been on its way out but since its OK set to MM then thats not the case

[Paul Barker]

The .6r one is either shorted by the circuit or internally shorted, since you haven't disconnected it I would expect the dead short to be in the circuit.

Tell me when you connect your meter probes together do they also read .6 r?

You need a low ohm meter for that level.

I bet the short is in your switch. Hard wire the option you are using at the moment. Who can be bothered changing cartridges all the time?

[John Caswell]

Paul,
You are not reading the information given, the 0.6R reading is on the tx side that is working.
Maybe you cannot be bothered changing cartridges but perhaps Bizzie has two turntables or two pickup arms.
Don't just bet on things, try leading the person to the correct way to find the fault

John aka Dr John

[Paul Barker]

Well I'll bet on the faulty channel being the 0.6r one, may be a mistake in his assessment of the situation.

As for a switch from mm to mc, hope it's a good one.

As for taking bets on what is wrong, the persons' statements don't always ring true and my chrystal ball needs a clean so I have a stab at what I think might be happening.