Philips PM-3208

Aan analoge scoops werken is altijd leuk. Afregeling is vaak wel erg veel werk bij de +100 MHz scopen. Maar dit is een 20 MHz scoop. Dat zit veel eenvoudiger in elkaar. Deze moest afgeregeld worden vanwege de vervangen onderdelen.

Je moet wel een echt serieuze reden hebben om ze te laten repareren want ze hebben zo goed als geen economische waarde meer. 

Maserati Biturbo ignition ECU

The problem zone

This is the ignition controller from an 80’s Maserati 430 Biturbo. Not something you see every day. Someone else tried to fix it but gave up. The problem according him was a burned resistor and transistor. He removed the resistor with some pcb damage and desoldered partly the transistor.  The via was still on the desoldered resistor leg. The resistor was a 0,09 ohm and I think somewhere between 2 to 5W. Not a value that is easy to find, but I found a 5W 0,1 ohm that measured 0,09 ohm. Because the original via was gone and the resistor longer I made a new hole  and soldered the leg on both sides to the pcb. Besides that I also made a new connection instead of the original via. Just to be sure. The original “dead” one was a bit roasted but still OK. So this was not the problem. Also the 2 darlingtons were OK. Tested them on my curvetracer to be sure. The transistors are not parallel or in serie. Each one drives it’s own ignition coil. 

The problem was a dead voltage regulator. An ultra lowdrop 5V automotive version. Some of the electronics had a 6V max. The rest of the damage was less as I expected. I was a bit afraid the eprom was damaged. But it tested Ok and I copied the code for safety. The eprom was probably protected by a 74HC373 octal latch that turned out to be dead. So he died not for nothing, RIP little chip. 

After checking and correcting bad solder joints and with a temporary 5V regulator it went back to the owner to check. And it worked. In the mean time the right regulator was delivered and I swapped it for the temporary 7805.

A “map” of the electronics

The unit has a microcontroller with an eprom and latch. They control the L482 Hall effect pickup ignition controllers. The latter each control a darlingtons that switches an ignition coil. There is a vacuum switch (I think) in the cabinet that connects to the 3 wires on the left. For the rest some opamps and a few nand gates. There is a conformal coating over de board. 

Triller element versterker Tira BAA120

De binnenkant

Een versterker om triller elementen aan te drijven. Je sluit er een functie generator op aan als bron dus eigenlijk een soort audioversterker.

Ik had geen triller elementen maar de versterker had voldoende aan een 4 ohm load. Deze zit in dat blik tussen scoop en amp. Een berg weerstanden parallel in olie gehangen. Werd aardig warm toen hij vol open ging.


Julabo oilbath

Julabo after repair

This is an oil bath with a compressor to cool and a heating spiral to heat the oil. There also is a pump in the bath. That was stuck. Besides that the two mains switches where burned and a lot of other small problems. It was not used for a long time. They are not very handy to work on. It needs to stay right-up because the compressor does not likes it to lay on its side.

The controller




Yep, that’s all folks

Here is an instrument you do not see every day. A magnetometer, the voodoo is in the fluxgate sensor. But that is nothing more as a boring grey piece of potted tubing. The principle is not so difficult but building a good sensor is. (so I’m told) The 3rd part is software to analyse the data.

The real magic comes from the man who uses this instrument to measure magnetic fields in X,Y,Z directions on places where they have, or want to install, a scanning electron microscope. Those magnetic fields can influence the beam of electrons in the SEM. Interpreting of the data is complex and not many people do this.

The owner was in Norway when it died and he contacted me. He brought it to me the next day and collected it the next day on his way to Germany. It was not a very complex repair. I also placed a new battery the owner already had. The old one bulged and was almost penetrated by the pins from the components because it is mounted under the pcb.  It had a low battery beeper but the owner did not hear that  so I mounted a bright blue led that lights up when the beeper goes on.