1955 Breville precedent It must be one of these two

1955 534A AC DW 5 452 6BE6, 6BH5, 6BD7, 6M5, 6V4 AORSM '55 101

1955 534B AC BC 5 452 6BE6, 6BH5, 6BD7, 6M5, 6V4 AORSM '55 100

Billy camera

http://hoarders.com.au/40s-breville-precedent-rolltop-radiogram-record-player.html.

Fadden's Precedent

Weekday (not this one) at this stage is good I don't think my email is hidden

I will contact likely, tommorow.

Marc

Those circuits have B+ Voltages on them at a couple of points. Do check.

The sets listed are "Back biased" 47 and 33 Ohm resistor. Check them. If B+ is high they may be the cause. If they are burned we may have a heater cathode short?

Do make sure that the first filter cap (16μF 350) does not go to chassis. Its negative end should go to HT centre tap (most negative point.).

HT Centre tap must also, not go directly to chassis.

Marc

Thanks for the call Marc it was very much appreciated.
I have learnt much about valves in recent months.
An unfortunate developement of recent days was an unexpected explosion in the vicinity of the Radiogram accompanied by a tripping of the circuit breaker.
The news is not good but I did discover a blob of soldier bridging to a spare pin on the rectifier valve.
This I assume was the reason for my problems and the cause of the gradual deterioration of the transformer mark 2. Well I know now! I will not be giving up though, I will endevour to stimulate the ecconomy some more and fix this golden oldie.

Interesting: I thought a Bandmaster I serviced recently had cooked a power transformer. Which would have been the first one changed out in forty years+, & several hundred radio's.

Despite having to still remove it, it was shorts from bizzare and normal circumstances.

Solder dags & flying bits of wire are the norm when "shotgunning" components, which in some sets, is unavoidable. One always cleans the pan & checks it for debris before live testing.

Lot's use a light bulb in series with the transformer when first powering it up. If there is a major overload it acts as a baretter and cuts the current to the transformer. I have actually seen a gramaphone needle take out a rectifier.

One then has another good look as to what "senior moment" caused that.

I always place an analogue voltmeter on the HT rails, (IC clips are ideal) to monitor the startup, this I was doing with the Bandmaster. At the first inkling of trouble, like the HT voltage failing to rise (within seconds with a filament rectifier) One hits the "Kill" switch (my isolation transformer has a kill switch fitted).


Bang! does not radiate good Karma, however I would still investigate source.

In vicinity of radiogram is a wide spacial concept. Is there an extension cable involved here? A dodgy feeder cable perhaps?

Or did the transformer cook from being left on when it should never have been on, per a previous comment?

We now need to prove, due cause. Eg.Shorted transformer or input cable fault.

Marc

The radio was working but with a difficiency of volume and clarity. Using a 150w bulb as protection I had no lighting. I also had a 1amp solid state circuit breaker instaled on the primary at the time of the short out.(this exploded) Maybe my protection was somewhat higher than it should had been. What should a 4/5 draw? My guess is about 100W. Also at the time of the short I had unplugged my input device (i pod) and all was silent.

I think the that the poor transformer had been pushed to it limits for too long and the primary windings finally exprired causing the short.

There was also evidence of fusion (non Nuclear) in the immediate vicinity of the solder dag.

I'm so glad that I never had these problems with my calson stromberg, Most be something to do with over confidence!

A cooked transformer usually emits an unmistakeable smell which clings to the windings for a long time afterwards.

Given the bulb and electronic breaker setup as described, I'm guessing that the breaker took the hit before the bulb had a chance to glow.

Very few sets would get to 100W without a very serious Pushpull like the MIdwest with four Valves in PP with 330V on them.

You need to pull the valves, to see if the secondary windings arestill ok and find out if there are any issues with the wiring on the transformer primary.

The only loud bangs on the secondary side a caps (normally electrolytics) going.

If it's loud enough to go bang without the fuse dropping, it still raises suspicion with me, as to it's origin being before the globe & fuse.

Marc

373 AZ Cooked!

Replacement?
Hamond
373 DZ
350.0.350 90ma
5v 2A
6.3 3A

Would this be a suitable replacement?

Will do these resisters 47ohm and 33ohm in 2W.
Where do they go?

and redo electrolytics in something big and blue.

The precedent dosn't use the 5v winding.
Why is the 5v used by other radios when the voltage is so close to 6.3v?
Billcamera?

It's to do with the heater voltage of the rectifier. Before 6.3 volt indirectly heated rectifiers came into use the most popular rectifier was the four pin 80 and its octal-based variant, the 5Y3G/GT. These valves were directly heated and had 5 volt filaments and thus were fed from their own transformer winding.

Those two resistors are the "Back Bias" and provide the "C" voltage for the tubes (saving on cathode resistors).

Those two are in series & take the CT of the secondary to earth (I have mentioned those two before)

With the 80 / 5Y3 the filament is the cathode, Positive is taken off of the Cathode.

As the cathode & filaments are the same thing the winding heating the filament must float above ground.

As a generalisation. In a heater tube the voltage between the cathode & heater should not exceed 20V, or there will be a flashover.

This is different with rectifiers eg 6X5 should not exceed 400V between heater & cathode, albeit that it is a tube notorious for heater cathode shorts.

If you get a new transformer, do not, as I said before power up until such time as you have detirmined where the overload is: It does not have to be on B+.

It could be within a valve. Or a filter cap could actually be reversed.

Marc

Hi,

have just acquired this model at auction. radio works fairly well but gram needs attention.
Does anyone have circuit diagram/list of valves for this model?

We likely had a circuit, but there were two different sets for 1955 and only the valves in it or the model number were going to detirmine which specific one it was.

The valves would have had numbers on them like 6BE6. These numbers come off on many valves if handled.

Marc