Corona lockdown fun: time for that unique Heemaf type 1955 from PEN

Heemaf type 1955 PEN
Heemaf type 1955 PEN
Heemaf type 1955 PEN before
Heemaf type 1955 PEN before

Let’s give it a total & in depth restoration, I thought. It certainly needs it and definitely deserved it. And with this Corona lockdown, wich was also implemented here in the Netherlands, I thought it would be a great project.

I do not always do a such a deep restoration. If the phone works well, I tend to leave the inside alone. I can only damage it, if I mess around with it.

In this case I had to undo all the screws anyway and I thought it would be nice to make the insides as nice & shiny as I could get them.

I thought it would be a good subject for a blog, and on the other hand it also shows how it sometimes takes years to get al the parts I need to do a restoration.

I reckoned it would be a reasonably simple project: cleaning, polishing and swapping some parts. That was all. But……………the goal posts kept moving.

What’s so special?

Heemaf type 1955 PEN kiesschijf
Heemaf type 1955 PEN kiesschijf

It looks like a normal Heemaf type 1955 to the untrained eye. But as you may have noticed, there is something odd about the dial centre. Instead of the hexagonal bolt, there is a smaller one with a ring. On that ring there are the letters Hoorn P.E.N. Hoorn is a city in the province of Noord-Holland and P.E.N. stands for Provinciale Energiemaatschappij Noord-Holland (provincial energy company North Holland).
Energy companies in the Netherlands used to have their own telephone networks and this telephone was part of that. And as you understand by now, to finding such a phone does not often happen!

Apart from that it was made in july 1955, so the very first year of production of this model.

There are no Philips logo’s on the switch hook studs, but Heemaf logo’s. It may very well be that this phone was not supplied by Philips to P.EN., but by Heemaf directly.
On the other hand, there is a Philips logo on the diagram inside. In any case, it is not a PTT version.

Minor issues

Heemaf type 1955 PEN minor issues
Heemaf type 1955 PEN minor issues

Of course there were some issues. Handset, cords and one of the feet was missing, for example. Bakelite was a bit dull. The mesh covering the sounding holes at the underside was gone.

And there was a chip off the left front corner, with a hair line crack.
I have many donor phones and spare parts, so fixing these problems would be easy. Or so I thought.

Perfect base

Heemaf 1955 PEN undersides
Heemaf 1955 PEN undersides

I thought about putting on another mesh. Just stick it on, right? So I removed the mesh carefully from a donor phone (smashed body shell, intact base).
Why stick on that mesh and not replace the base? Because I wanted to keep the original production date.

The mesh did not come off as nice as I wanted. And I had trouble thinking of a way of sticking it on my P.E.N. phone so that it looked factory fresh. The result would be uneven.

For years I examined every ad for a Heemaf type 1955 in the hope that I would find one with the same production date.
I even found one! A lady on the other side on the country had a Heemaf type 1955 for sale with the same production date. But she did not want to send it. Pick up only. And at the time I did not have the opportunity to pick it up. So it slipped through my hands………..

And then I found a very similar one, made only one month earlier. After much contemplaining I decided to use that as a donor.

Crack and chip: who expected diagram issues?

Heemaf 1955 PEN 2x front
Heemaf 1955 PEN 2x front

So, swap the body shells and the crack and chip problem would go away, right? Just use the donor phone. It has an undamaged body shell. Well, yes and no…………..

It turns out it has a different diagram. Yes, one month difference but the diagram is a little different. And of course the wiring of the donor phone is also a little different too!
I washed both body shells, in the hope the diagrams would come loose, as this sometimes happens. Not this time.
So, what now? I wanted to keep it as original as possible. Use the donor body shell, base and insides? Or swap everything?

Heemaf type 1955 PEN crack and chip repaired
Heemaf type 1955 PEN crack and chip repaired

I chose the latter. I meant that I had to remove the original innards from the original base plate, put it on the donor base plate, use the original body shell and repair it. Sigh.

Yes, I was going to do a simple body swap but ended up swapping al the insides and repairing a crack and chip.

How did I do that? Here is and article about repairing a crack in bakelite and here an article on how to repair a chip.

Check out this picture for the result. I am reasonably satisfied. The chip repair is a still a little visible.

Polishing the inside part: screw trouble

Heemaf type 1955 PEN inside restored
Heemaf type 1955 PEN inside restored

It was going to be straight forward from here. Cleaning, polishing, finding some missing screws. So I went over all the insides, as I had them disassembled from the base plate. They were in fine condition, albeit a bit rusty in some places. And there were some screws missing from the row of terminals.

I also noticed that a lot of the screws had damaged heads. They had tool marks on them, from using the wrong size of screw driver. Hmmm, let’s do something about that.

Heemaf type 1955 PEN underside finished
Heemaf type 1955 PEN underside finished

So, I started cleaning them up and trying to undo some of the damage. And as I started searching for replacement screws, I thought I might as well look for undamaged ones.
Easy peasy, right? No. It turns out these early Heemaf type 1955s had slighty different screws! The early ones were made on a lathe or similar machine, later ones were pressed so they had slightly rounded edges. Exactly the kind of detail that bugs me endlessly if I get it wrong!

I spent hours searching through my donor phones and spare parts to find the right ones!

Handset and cords

Heemaf type 1955 PEN hoorn
Heemaf type 1955 PEN hoorn

The handset was missing on the P.E.N. phone. There was one on the donor phone. But it was gutted; all the screws and brackets were missing.
So I spent an evening searching all these parts and especially the right screws. See also the paragraph above. 🙂

Most importantly, at least I think so, I added a rare part. It is the original style of strain relief for the handset cord. Originally it was a small metal plate, secured by a bolt. It secured the ribbon, attached to the cloth cord.

Most Heemaf type 1955s today have a curled cord with a different strain relief.

I even went through the trouble of searching through my stash of transmitters and receiver to find the proper ones original to this model, made by Philips. I could not find any with the right production dates, but I did get some good ones from the late 50s.

The cherry on the cake: a part I had savoured for years

Heemaf type 1955 PEN terminal box
Heemaf type 1955 PEN terminal box

A few years ago I was at a flea market and rummaged through a box of bakelite electric material. There were light switches, doorbell buttons, mains sockets, you have probable seen similar boxes. Then I spotted this small bakelite wall box covered in white paint. I recognised it immediately. It was a Heemaf terminal box. It was exactly the same as a PTT terminal box, but without the beatifull logo.

It was only 1 euro. I did not have to think for very long.
It has been in my display case for years now, white paint and all. Waiting for just the right phone. That Heemaf phone that was not used by PTT. Like this PEN telephone!

I learned a lot

Heemaf 1955 PEN inside new and old style
Heemaf 1955 PEN inside new and old style

Just when I least expected it, I learned a lot. Having restored literally dozens of Heemaf type 1955 I thought I knew them by now. But until now I had not noticed the style of bolt heads had changed through the years.
Not only that, but I also noticed that the type of coil is different on early models. The P.E.N. phone has an older style coil, which is round. The newer production models have a square more modern type of coil.

Oh, and there was the strip with numbers under the bank with terminal screws. On older versions it had bare metal numbers on a black background, on newer versions it had black numbers on a bare metal background.

And last but not least, the early ones have a small strip of isolation material (pertinax?) under the capacitor. This was omitted on later versions.

This was my Corona project, what was yours?

Heemaf type 1955 PEN side view
Heemaf type 1955 PEN side view

So, cleaned, polished, repaired, tested and photographed. I am very happy with the result. This rare phone can now take its proper place in my collection. In the end it took much more time than I thought. Not that I am complaining, it was great fun and I learned a lot.

And what makes it a Corona project? Well, it turns out I have a vital job, as they call it here. So even though there is a lock down, I can and must continue with my job and of course am happy to do so. Good thing I can work from home.

So, unlike people who cannot work anymore, I do not have time to clean the attic, do the garden or build that shed. The difference is that I do not have to travel to the office, which saves me 2 hours every day. That means I have more daylight time to work on my phones. So the kids are not yet to bed, so I can rummage around in my storage area and use noisy tools.

And this is just one of my Corona projects. I am working on some more.

How about you?

What is your Corona project, if you have one? Please leave a comment and tell us about it, telephone related or not.


  1. Hi Arwin.
    Question, how do you keep the enamel finishing of the dial plate undamaged? I can still remember the one you helped me to replace, all scratched.


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