APHEX CX-1 comps with meter problem

[Andresound]

Hi Guys,
I have a pair of these units and a pair of the EQ's all with JENSEN trannies. I have recapped them. They are working, but on one comp, the meter only works the bottom half of the bar graph. Does anyone have any ideas?

 

[analogguru]

So I was curios what you were talking about and therefore I googled "trannies".

Do the trannies you are talking about look like these ?:

 

[fazer]

It’s weird sometimes with google search results. You never know what will pop up.

bar graph. Does anyone have any ideas?

I don’t have a schematic but I would think there is a problem with the drive transistor or maybe LM3900 chip if that’s what they used or the voltage from the GR function switch has low voltage. Check for backwards caps. Solder Bridge. Burnt transistor???

 

[fazer]

So schematic shows LM3914 driving the display. Since you have both units, measure between the good one and bad one and where voltage is low and check for solder bridge.

Here is the schematic if you need it

 

[Andresound]

Will do. Thank you for the schematic

 

[pucho812]

If it’s not the chip, then it will be a bad led or more then one. Most of the time when this happens it’s a dead led and the metering won’t show beyond the dead one.

 

[plimousse]

Hi,
It is often a VCA problem that controls the display
A13 in the lower left corner of the diagram
Cheers,
P.

 

[ivan]

I had aphex cx1 about 20 years ago. I think I had a similar problem and after turning some trimpot for meter calibration or GR everything was ok.