G'day chaps,

Will pass on all material later today and will post same in this thread tonight.

Brad: Thanks will do some head scratching when I get it.
Marc

OK got the circuit & its readable enough to formulate a plan.

Re stuffing the cans can be frought with problems for the inexperienced. I rarely do it. The traps are polarity and getting the negative tail to frame as you cannot soler to the aluminium with conventional soldering.

The voltage chart is for a meter of 1000 Ohms per volt. In places like the screens a digital meter will likely read higher.
Often digital meters have problems when there is RF riding on the DC voltage.

As you had noise previously we assume the speaker transformer is probably ok. There is no negative feedback on this.

There are voltages listed on the circuit. The circuit has back bias. The 6BD7 is part of the audio circuit when looking at that (pre amp).

My first project would be to check everything against the circuit to see if you have not put an item on the wrong thing. I would also check the back bias resistor (CT of transformer to ground looks like R25) The plate resistor of the 6BD7 (looks like 220K) which can be done in circuit and the cathode resistor of the 6M5 (in circuit)

Only after all of that would I contemplate checking voltages. Beware of the markings on several of the modern (axial in particular) electrolytic caps, it is very easy to get these very wrong, as the markings can be quite confusing. Reversed Filter caps can be nasty.

I note also that there is an electrolytic "decoupling" (to a point) Pay attention to it & the value of R5 (this is a voltage that will read higher with a digital meter. R5 can be checked in circuit with SW in PU position.

Note voltages are in "Radio" position.

Fit correct dropping resistor. Note that speaker transformer wire is on the cathode of the rectifier. The ripple there does not matter, as the plate does not amplify.

Have fun with that lot & feed back results / hassles & I will see if this drops the login as soon as I post (yet again).

Marc

Thanks.

Now that I have the cct diagram things are suddenly clear. I checked the resistors you said. and this is what I found

The resistor from the ct of the power tx is 47ohm and matches its colours. Just not located where you think it would be

R5, R12 and R15 Completely o/c
R16 Good.

What would have caused a failure like this? Could it be from one of the power supply electros failing?

R5 supplies the screens of V1 & V2. Likely causes,wire short, valve short, overload. The decoupling electrolytic would feature high on the list of suspects.

Electrolytics that have been left unused, for substantial time, especially the older ones; Loose polarity and present as a short circuit. This is one reason why you never power up an old radio to see if it works (another story).

R15 is a bit unusual, it's the grid stopper and there is no way that I can see what could provide sufficient current to kill it. It is however, not unusual to see one there go high (6V6 worst offender?)

R12 is the plate resistor not unusual to see one go, coupling capacitor (C17) may have been involved in that, which the 6M5 would not appreciate.

If you can get your hands on a valve tester, or someone with one, it may be an idea to feed the valves to it, to make sure none are shorted.

But lets face it progress is being made.

Beware of the supermarket resistors you use many, half watt, will not take the voltage: use 1 Watt. Circuit is a bit unclear so I hope I named these correctly?

If you kept the cap? I often hit them with a megger at their rated voltage (or close). That should give a clue. Resistance of the cap should be infinity. Do not do this to electrolytics.

Marc

Dropped the login on post again?

I totally recapped (except for Micas) the entire radio before turning on.

I dont know anyone with a valve tester. is there a way I could use a multimeter / Megger to test valves.

Valves: Only thing you can test with a multimeter is cathode to heater shorts on heater valves. Sometimes an element short to another in a Pentagrid: The later is not reliable as I deliberately tried that on a 6V6 recently, that I had proven to be shorting.

You just may have to take a punt. As the set sorta worked originally they just might be OK.

The only tester that I have for minatures, is one I aquired from junk. Tech 15 I am informed. I can make a card as I go using known good tubes the same as the one I need to test, but... It only had one card that had been part eaten by the rodents.

Would like to get my hands on a manual for it.

Australian Mica's rarely fail. If they do it is normally the ones with lots of DC on them which can often be found, as a generalisation, decoupling, from start to finish. Yes sometimes (Astor for one) on the output valve.

Probably no more replies for 10 hrs.

Marc

It Works!!!

I replaced the Resistors that measured out of tolerance and now it works very well. With all the original valves as well.

It even picks up all the strong stations as well as a few from far without an antenna connected.

Thanks to all that helped me get this working. I now have a valve radio to listen to the football on in the shed.

Another logical plan leading to a swift conclusion. This I hope leads to the confidence to attack another. Clearly the provision of a circuit was a major factor and is an imense advantage, to anyone unfamiliar with a set.

The catch 22 is being able to read and interpret it. That's where forums like this are the greatest benefit. You can often find people with ideas and guidance that will get you out of the poo.

Good work.

Marc

Another logical plan leading to a swift conclusion. This I hope leads to the confidence to attack another.

I'd bet a house on that. I've never met anyone who started collecting radios that didn't think they just needed one more on the shelf. It has advantages and disadvantages but radio collecting is extremely addictive. But I reckon that is a good thing.

Clearly the provision of a circuit was a major factor and is an imense advantage, to anyone unfamiliar with a set. The catch 22 is being able to read and interpret it.

Circuit diagrams and resources for them are in very short supply and this is unfortunate. Marcc and a few other members here have contributed a great deal as far as this is concerned. I think I've had no more than five in my posession in the 22 years I've been collecting.

I'm glad you got your set going Dan. Nothing is better than watching a once-lifeless relic come to life again and the older the set is, the better it feels.

Thanks Guys. Now that I got this working I think it will be time to get into the old Wooden case radios that I have sitting in my shed, One is the Solonola/Aristocrat that I mentioned in a post before trying to Identify it. ant the other is a AWA battery portable mod no 451P.

Even though I am an electronics technician. I always find a CCT diagram to be the best tool in working out what is wrong followed by my meter!

Test post.