Hi All,

I'm looking to try and restore an old HMV Internationale Radiogram I've inherited from my grandma. I believe the power transformer needs replacing but I'm not quite sure where I would be able to find a suitable replacement. I'm not educated on how to read schematics so some assistance on exactly what I need to look for in a replacement transformer and ideas on where to buy would be great.

Power transformers are generally fairly reliable.
Firstly you would need to establish this.
And no doubt it requires a lot more work on it, to make it safe, reliable and perform well.
You probably need to find someone local to assess it, as unless experienced with this type of work, it can prove to be quite dangerous.
JJ

As above, don't attempt work on mains-powered equipment unless you are fully aware of technician safe practices.

I would second laying off the transformer and touching any thing until it has been assessed. That is my first step. Powering it to see if it goes, is never the first step.

I did within the week point out on another forum, that I considered his methodology flawed and I saw no evidence to support failed transformer. At the end of the day we were right and our suggestions have it going.

As you can see that was (like a lot of stuff) taken out of service as it was faulty: That is why I say never power, that's why. This sort of thing happens at the local Mens Shed and is another warning. No one takes a donated mains item and puts it into service, nor can it legally be sold without checking. Many items are rubbish (Common charity problem) and many are not commercially viable to repair.

I a recent run on several items the trend of around 10% defective, or absolutely unsafe applied. Many of these come from Dads shed after he's pegged out. Sending the power tools & such to the Mens Shed does help them as if not needed at that shed they can be moved on, or sent to another in need. We did send a pile of tested & working tools to Kiribati, in an aid program.

Photos uploaded.

That's about all the info we need!

It would be unusual for the transformer to fail unless there was a short somewhere and it's been overloaded. Hard to tell from the pic but it does look like that would be a possibility. A shorted rectifier diode is the most likely reason.

I used to service these units when they were new and under warranty. It was very unusual for anything more than a broken stylus to happen to them.

They are not very powerful - about 2 watts RMS per channel max. But the speakers were reasonably efficient.

It can be fixed, substitute parts are available. A suitable transformer if needed could be sourced from Jaycar or Altronics.

If you can use a multimeter and a soldering iron we can talk you through faultfinding and fixing it. My email is not hidden.

Before condemning the transformer I'd check the 2 rectifier diodes, then check out the transformer for continuity and voltages.

If the diodes shorted they may have killed the transformer.

The transformer itself appears to be centre earth with 6.3 and 12.6 volt windings on either side. An exact replacement might not be available, but there's plenty of alternatives that might require a little bit of rewiring in the area.

If you do need to replace the transformer, the M2165L from Altronics would do the job.

I concur with Robbbert, 12.6 volts a side, with taps for the dial lamps.

The M2165L is a little bigger but should fit OK. It has two windings which you can connect in series.

Like this : 0v ---- 9v ----12v -- Ground and connected to -- 0v ---- 9v -----12v
.................( First winding)---------------------------------------(Second winding)

The diodes connect to the outer 0v and 12v pins. One of the 9v pins will give you 3 volts for dial lamps, the other will give you 9 volts.
That should give you around 17 volts DC, which is about right.

You then have a choice of 3 or 9 volts for the dial lamps. Not perfect but it's workable. I'd go for 9 and replace the lamps with 12 volt.

If the original transformer is cooked I'd replace the diodes anyway.

On the power supply diagram, to the left of the main filter cap, C64, there's an unreadable voltage written there.

Is it 10.5 volts? or 19.5? I can't tell. But I think it would be important to get close to that value.

As far as the dial lamps go, they could always be wired in series if it helps with getting the right volts.

As I recall that model ran about 20 volts - about the maximum for an AC127 - AC127 germanium complementary pair.

When these transistors became obsolete, Philips locally introduced "manufacturer's numbers" for silicon replacements in TO18 metal cases.
The numbers told you what it was.. Example - going from memory but I think this is correct:

OC9288 was a PNP, 800mA, 80 volt transistor.

Connecting dial lamps in series may not be possible because I think the holders are grounded to the chassis??