Ramsey CT-90 Counter Fault
Have a Ramsey CT-90 Freq Counter. Works fine on ext ps, but when fitted with int batteries, seems to work ok (not very bright display) but batteries get v hot!!
Looks like a short somewhere in battery feed circuit, possible a cap gone leaky. Have looked for circuit diagram on internet, but so far no luck.
Anyone out there help?
OK, no takers. Found diagram on internet eventually, 2 hours searching!!
Have you found the trouble?
Don't feel bad my CT-50 went up in smoke yesterday.
"Have I found the problem".
Not sure, is the answer.
The manual I have now downloaded, specifically refers to using 4 x AA Nicad's, (ie 1.2v per cell) and the unit circuit shows that it will charge these, when an ext PS is connected to it.
OK so I was trying to run the unit on 4 x AA "standard non-rechargeable" cells (ie 1.5v per cell). I did not however have the ext PS connected.
So although the unit was working, why were these cells getting v hot? Obviously something in the circuit taking a hell of a lot of current.
A number of diodes in circuit should have meant that the only thing taking current was on the downstream side of the bridge rectifier and 5v regulator.
Should be a simple job to track down a possible S/C diode or similar.
It will have to wait a couple of weeks!! I am in VE3 land at moment.