Tektronix 324 & 324
I bought several of these off of Ebay and ended up making repairs on most of them.
All had dead or very weak batteries.
A design oversight put a small load on the batteries when off.
A few had some bad electrolytics.
I did not routinely replace any parts.
Draining the batteries when turned off
This was due to the voltage divider in the charging circuit being left connected to the battery when off. My solution was to isolate the offending part of the circuit with a PNP transistor that is turned on when the 323 is plugged in. Others have proposed this same solution however I found that the charging current was lowered and a quick check showed the PNP conduction time was varying with the ripple on the DC at the out of the rectifier, so I added filtering to the base and cured the problem.
BqBattery Pack:
Photo:
Power supply/Battery Pack
These have NiCad batteries in them which will usually be either extremely weak or completely dead. I have replaced these with 4 Ah NMh C cells and 2 Ah AA cells. The 4Ah can give 15 hrs or more run time in the 323, but are a bit oversized and require a bit of extra care to fit since the originals have flat ends. The easiest thing is to use a 6 AA cell holder with a 9v battery clip on it and get about 8 hr run time on the 323. The 4Ah cells gave about 9.5 hr on the 324, much more in the 323. I found batteries on Ebay tend to lie about capacity & now use only name branded low self discharge cells.
Tips: Count on some screws being corroded/seized so get spares ahead of time (4-
Most of the battery jacks are cracked at the screw hole, so reinforce it before it breaks completely.
The wires that connect to the scope are color coded with matching labels on the pins.
Expect to clean up some corrosion from battery leaks. Probably replace the foam.
This can be difficult to insert in the chassis -
A dead battery will prevent the unit powering up with external DC, depending on the position of the selector switch.
WARNING: Sony makes a TV power cord that looks like the 323/324 cords and fits, but is wired such that one side of the unpolarized power line ends up on the chassis!
Three views of the power supply/Battery Pack
Side view of battery + spacer.
DC input jacks are frequently broken at the mount screw. Epoxy didn’t stick very well, so I filled in the curves and used a tywrap to strengthen
Original Sub C sized batteries removed and 9v battery clip wired in.
6 x AA battery holder with spacer on top (1x4?)
6 x AA battery holder in place with low self discharge Nmh batteries
