Alrighty….well I’m into the 2nd vinyl & neither speaker has cut out so far!!

So perhaps it is a damaged ground wire? Joining them at the headshell seems to hide the issue for now anyway….so I just need to rewire the tonearm next - the R channel wiring (now L) seems to be quiter & slightly distorted so I imagine that wire is on the way out too.

I undone the arm pivot screws on the spare turntable I have here & there’s a hidden screw under the arm which allows the headshell plug attachment to be removed so rewiring seems to be quite an easy actually - just have to grab some 4 core wire.

Getting there now!

If there is a perceived difference between the amplifiers; That goes back to proving them. It is always a case that in the ideal scenario, all of the voltages will be the same on every tube element. However, with the effluxion of time things change and tubes wear and there is no guarantee that the the tubes were ever the same, or are a matched set. That has to result in uneven reproduction.

To eliminate the amplifier as a cause the only really method with any semblance of accuracy is to feed in (as before) a single tone, with the balance control in the middle and either measure the AC voltage off of the plate using a meter on AC with a series cap in the lead, or an oscilloscope as it can measure the amplitude of the tone.

Marc

Yes I wonder how much is just perceived…I mean there was a big R difference on turntable before….but now that has been swapped to L which means tonearm wiring probably is on the way out or cartridge just produces weaker sound on one channel.

It isn’t cutting out anymore - so that must have been faulty R ground wire.

I will try my other cartridge just to see if the weaker channel seems more even - that still could be cartridge issue I guess.

Radio variance is less & probably not noticeable to anyone else - if swapping cartridge makes it similar to radio it probably isn’t worth pursuing!

Either way it sure sounds better than it has - no more cutting out & with mid range speakers working now too it is a nice machine

It just occurred to me. You have electrostatic speakers I think in that one am I correct.

Yes it has electrostatic speakers - they seem to work ok although only if you have treble up (which I generally don't).

I swapped the cartridge over and it actually seemed like sound was quite good on both channels on gram!

However the slide in rear connector is fidgety and I think one of the cartridge plug sliders wasn't connecting properly on this cartridge as the R channel cut out part way through a record.....I pulled connector out & one of the sliders looked like it lost its tension so I bent it slightly & reassembled.....it seemed good again.

But then the L channel was distorted!

I pulled headshell off again & it looked like a couple of strands of the headshell white wire where it joins the cartridge plug were touching the ground terminal....so I've pushed them aside & great again - until R channel cut out again just now.

There's so many variables but seems the issues are between cartridge and the input to the chassis as Marc said...it's just a matter of ruling each out....will know a lot more once I replace tonearm wires which seems like it will be quite easy once I get to jaycar to grab some 4 core - that could be causing these issues still.

But for the moment I've listened to another vinyl and it sounds really good with no distortion - probably the best it has sounded! But waiting for it to cut out again…

Albeit that there are distinctive signs with dirty pins on tubes and a corrosive socket. The fact that you pull a tube and nothing happens is cause to examine the jaws of the socket and all of anything attached to it. Probing with a chopstick, is not only good for finding spurious oscillations, but can find bad jointing i.e. "Dry joints" and other bad connections.

The best way of testing the tube is as before: Move it to the other amp. On bad corrosion in miniature sockets: Tip cleaners for Oxy welding are on my list. Have Oxy welding Industrial & Jewellery.

Well as a quick update I’ve spent hours on this thing changing tonearm wires!

What seemed easy wasn’t - I tried rewiring the old spare turntable arm as practice but the headshell to tonearm joint is plastic and on the last pin I slightly overheated it which meant it no longer moved freely.

So I pulled the proper turntable tonearm and just joined the wires a few cm away from the connector.

Upon reassembly I had no left channel!

Turned out one of the spring sliders in the cartridge connector had broken….so resoldered in a new plug.

Then all worked….until the R channel cutout!! Ahhhhh

I swapped the other cartridge in to check but it is the same - intermittent cutout that is fixed by quickly flicking to radio then back to gram.

So looks like fault is in chassis - and I’m not far from cracking it lol

Yep the fact v4 can be taken out and makes no difference is a worry - but I feel I need to solve this turntable issue first as it’s really bugging me now!

I guess I’ll have to review the pre amp circuit again….the tube socket is an interesting one is there a way I can check them with it turned off? What makes this chassis tricky is I can’t listen to it operating while out as speaker cables need to be disconnected before chassis can be lifted out - smart design hey! I have sandpapered pins & sprayed cleaner on input tube socket but I guess I can’t be certain it’s contacting. Preamp seems to mainly consist of resistors I can probably just replace them all as they all measure up correctly - but perhaps go open occasionally?

Old radios ahhhh