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Getting a high voltage reading on the F-2619 board of my 9090DB

angelaudio

angelaudio

Super Member
Initially this 9090db was getting no FM or AM reception, and after doing some research found that the F-2619 board supplies 12.5V to the tuner section which wasn’t being supplied because of poor solder connections on the heat sink and TR01. After resoldering the connections properly I made the adjustment to VR01 to show 12.5V. The reading was taken from the positive lead of C05 to chassis ground. Initially I got it spot on but I went back in today to check if my dial pointer lamp was being fed 6V (which it wasn’t) and checked to see if the F-2619 board was still supplying 12.5V, and it was reading very high at about 17V. What could be happening here? Adjusting VR01 wasn’t doing much to change the voltage this time around, could it be a bad VR01?
 
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Either TR01 has shorted, or there is an open or short with TR02 or TR03, or the zener diode. VR01 is probably OK
 
I was testing the transistors and the zener and I’m not sure if I’m doing it correctly. For the transistors I’m measuring resistance from B to E and B to C and I should be getting a reading between 500 and 1.5K ohms right? And for the Zener I’m not sure if I’m testing it correctly. I am measuring forward voltage and getting about .6V and reverse voltage I am getting strange readings starting off at about 2.6V and climbing gradually.
 
angelaudio said:
I was testing the transistors and the zener and I’m not sure if I’m doing it correctly. For the transistors I’m measuring resistance from B to E and B to C and I should be getting a reading between 500 and 1.5K ohms right? And for the Zener I’m not sure if I’m testing it correctly. I am measuring forward voltage and getting about .6V and reverse voltage I am getting strange readings starting off at about 2.6V and climbing gradually.
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I assume you are using a digital mwter, as I use a old analog meter, which is better in my opinion that digital.
On analog Triplett meter
Mid scale deflection B to E, and B to C (foward bias direction)
Infinity B to E and B to C (Reverse bias direction
Very high resistance E to C in both directions.
Note that in circuit, readings could be affected.

On digital meters, they usually have a diode function you can use.
 
Yes I am using a digital multimeter. I might have to take them out of the circuit then because I was getting inconsistent readings on the three transistors.
 
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