"Rectifier" 161A/162A
 

Although known as a rectifier, these are actually chargers, powered respectively from a vehicle and from the mains. As these are used for charging Tester 301A, and presumably Tester 301B, both of which I have, I would like to be able to emulate their function, but to do so I need to know what output they produce. I certainly don't hold out much hope of acquiring an original unit.

Any help in identifying what I need would be appreciated.

Re: "Rectifier" 161A/162A
 

Would a reverse-engineered circuit of the Tester 301B (alas without the charger as I don't have one either) be any use?

The Tester 301B has an internal NiCd battery of, IIRC, 12 cells. The charger circuitry in the unit starts with a step-up SMPSU circuit so it looks like you could charge it from a 12V input. I've never tried, the cells in mine are totally dead. The XLR connector on the Tester 301B has 3 pins which are : common -ve, +ve input for the charger, +ve input to run the unit without using the internal battery.

You can power a Tester 301B from 12V fed on the correct 2 pins of the XLR connector. That will work even if the internal NiCd cells are totally dead.

Re: "Rectifier" 161A/162A
 

Thanks, I'll give that a try.

Re: "Rectifier" 161A/162A
 

Do you have the pinout of the XLR connector?

Re: "Rectifier" 161A/162A
 

Yes thanks. I can't remember it at present, but I made up an XLR by looking at the wiring inside the 301A when I got it - and I assume the 301B is the same.

I must also have known the voltage for the 301A at some stage as I had it working despite a dead battery, but I seem to have failed to make a note at that time.

Re: "Rectifier" 161A/162A
 

On the Tester 301B there seems to be a pin on the left, a pin at the bottom and a pin on the right of the XLR.

The pin on the left is ground. The pin at the bottom is the +ve input to the unit to run it without using the battery. The pin on the right is the +ve input to the charge circuit. You can check it as follows :

Ground goes to things you might expect to be system ground, like the -ve suppy pin of the TTL ICs and the common (also tabs) of the 7805 and 7812 regulators.

Switch to 'Ext'. The +ve supply pin will now be connected to the 2A fuse (F1) on the main board.

Switch to 'Off/Charge'. The charger +ve input is then connected to the 500mA fuse (F2) on the main board.

The battery in the Tester 301B is at the bottom. To get to it you have to remove the top cover, then the fixing screws on the main board. Unplug the battery cable from the front panel PCB (Conn 3) then lift the front panel and mainboard out together. It's made harder than it should be, the main board plug into a Molex KK type connector on the front panel PCB so they have to come out together. And of course there's the CRT.

With that out, the battery cover is obvious. Remove it, then there are 2 sets of 6 NiCd cells inside, plugging into a little connector bracket.

I can e-mail you the circuit if you want it.