The PPGs’ program storage depends on the battery having enough juice. My PPG wave 2’s battery started to shown signs of a small leak, even though it was supposedly replaced only a few years ago by the previous owner. After the battery was replaced I wanted to reload the factory programs. I had some luck following the instructions in my own video that I published four years ago (yes, I partially have this blog to compensate for my bad memory). Read the post here. Below is the cable I got from the previous owner, that actually works, and is used in the video. Please do continue read, a neater solution is presented later in the post!
The other day I got contacted by a fellow PPG owner that still had struggles reloading the programs, even though he carefully followed the video instructions. We had some FaceTime discussions and those are the questions that arose, that we both thought would be nice to have answers to:
- What is the pinout of the cassette interface? The one that came with my PPG is a home made, spliced together thing.
- Which dump of the ones that are floating around is the factory dump, and why are they so hard to restore?
CASSETTE interface pinout
The PPGs use a DIN connector for the CASSETTE interface. The DIN connector was very common, and there are loads of variants with different amount of pins and varying uses of them. There’s a standard numbering for the five pin DIN connector, the type that is used on the PPG for cassette, MIDI cables etc. Note that the numbering is not in the physical order they appear! Also note that the numbering could be mirrored, depending if you’re looking at a female or male connector.
For modern use, we need to have an adapter to RCA or 1/4″ jacks. Unfortunately there’s a plethora of different adapters for different purposes. You can find two adapters from DIN to white and red RCAs, but they could be differently patched depending on if they’re made for a tape recorder or an amplifier. I found both variants in my old-crap-that-might-be-useful-some-day-pile. The only thing that you can probably be sure about is pin 2 being the signal ground. I found an adapter that has all four RCAs in that same pile, which made investigating the pinout easier.
I first tried the CASSETTE➡2 to see which pins the program data was outputted on. I then tried to reload the dumps in the PPG using the other two pins. This is my conclusion, I have double checked this a dozen of times:
In the PPG 2.2 service manual I found this, which caused a lot of confusion in the beginning of my investigation. Once I figured out that the image is the male side of a cable and not the actual female DIN connector on the PPG, it all made sense. Otherwise they would have switched “sides” on all pins requiring a different cable for a 2.2, which seems like a pointless thing to do. Yes, it’s me who added the red text!
Program dumps
When you dump to tape from the PPG by using the CASSETTE➡2 function, you first get a calibration tone that is followed by the data itself. Some kind of checksums are also in this audio, so that the PPG can discover if the data is corrupted or the if the transfer is too unstable. The PPG will respond with a CASSETTE➡9 when an error occurs, or a CASSETTE➡0 if everything went well.
Old dumps
In my collection I have two dumps, one called w20_fact.wav that supposedly is the factory programs. That one I’ve never managed to load into the PPG. It’s 8-bit and sounds a bit distorted. This has no calibration tone, the data starts directly.
With the purchase of the PPG I got an MP3 file PPG Wave 2 – 3.mp3 which is the one that I’ve managed to load to the PPG and the one used in the video. It has a calibration tone, but someone seems to adjust the recording level up and down, just before the data starts. I found out that starting at the end of the calibration tone where no volume changes are resulted in far more successful loads. I don’t know if it’s stereo because it was recorded from both pins 1 & 4, or if it became stereo when converted to mp3. No one probably knows.
New dumps – a.k.a. the “REDUMPS”
As I had more knowledge about the pinouts, I could now make a successful and audibly cleaner dump out of my PPG that was loaded with PPG Wave 2 – 3.mp3. It was recorded with no gain applied using my spare Focusrite 2i2 in 24/44.1. I got a nice steady data stream peaking at -18 db. I did two recordings, one for each pin (1 & 4), and got similar results.
The PPG has a CASSETTE➡4 function that let’s you compare the contents in the PPG’s memory with the content from the cassette input to validate that the dump is correct. It’s similar to CASSETTE➡1, but doesn’t actually store the data in the PPG.
I tested to play back both recordings to both input pins (3 & 5) in all possible combinations, and all of them were successful. I played them back both from the MacBook’s internal sound card and from an Antelope Orion 32 output.
Next question was, could I modify the w20_fact.wav so that the PPG would accept it? By normalising the data to -18 db and adding the calibration tone from one of my new dumps at the beginning, I kept my fingers crossed. And amazingly, it worked, for the first time ever! I then immediately made a dump of it. Playing some of my favourite programs, I really couldn’t hear any difference to the PPG Wave 2 – 3.mp3 programs I had loaded before.
This made me wonder, are PPG Wave 2 – 3.mp3 and w20_fact.wav the same? By using the CASSETTE➡4 function to compare the PPG’s programs with all of my new dumps, I had “proof” (given that the PPG is accurate enough), that they are the same. The PPG wave 2 manual I have states the following in German:
Die auf der Kassette aufgespielten Daten werden mit dem Speicherinhalt verglichen. Bei Fehlern die beim Aufnahmen entstanden sind erscheint eine “9” auf dem Display.
that translates to:
The data recorded on the cassette are compared with the contents of the memory. A “9” appears on the display for errors that occurred during the recording.
Download REDUMPED factory programs
This is w20_fact.wav loaded into my PPG wave 2 and then directly dumped from pin 5. There’s no point adding the other dumps since their contents are the same!
w20_fact factory programs “redumped” in and out of my PPG Wave 2
Findings
- Both of the dumps I had had the same contents and are probably the factory programs.
- A clean dump is much easier for the PPG to load, than the low quality ones I had (doh).
- A stable calibration tone at the beginning is important, the overall volume not so much (as long as it’s stable).
