Hartke HA 3500 distortion on Solidstate preamp

[Burien]

Hello All,

I have had my Hartke for well over 10 years now and have performed several maintenance repairs to keep it in top condition as this is an amazing amp!

recently i have discovered that the solidstate preamp is distorting slightly, this is a heavily gigged amp. the tube side is fine. I wanted to ask if anyone else has experienced this on an amp before and if anyone has any tips for where to start my investigation?

Thanks in advance

[J M Fahey]

Best is to send a clean s100mV sinewave in the normal input and scope the ouitput of either preamp (tube/SS) .
*Then* you will be certain about it.
Otherwise it becomes a shot in the dark.

[Burien]

I had a feeling that i would be. I will have a go at checking the sign wave. I am hoping that i will find a dry joint somewhere. I haven't had to do any work on the preamp before. Learning is good though!

Thanks anyway

[mozwell]

this may help to follow the signal through.