Pioneer GM-D8400M

RiLoWa

Member
2010-08-25 7:06 pm
Illinois
Ok replaced the TC74AC14F (IC303) and the NJM311M (IC302) in front of it. The new logic IC gets hot also.

This amp had extensive damage to all of the voltage regulators so it didn't seem out of line that this IC could be defective.

I have clean audio signal up to the input of the NJM311M I replaced so the only other IC I suspect damaged is the TND505MD drive IC.

I have the service manual if you want / need a copy.
 

RiLoWa

Member
2010-08-25 7:06 pm
Illinois
An update to this repair - I finally received a new TND505 (IC305) and installed it tonight along with a new IMT4 (Q301). The TC74AC14F (IC303) still gets hot and no audio is reaching the speaker output terminals.

The last place I see audio is Pin 2 of the NJM311M (IC302).
 
Not sure how reliable the ACV readings are. I checked each several times and each time the ACV and Frequency were slightly different but here is what I get:

R319: 000.0mVDC ~81.5mVAC ~60KHz
R320: 000.0mVDC ~82.0mVAC ~60KHz
R321: 000.0mVDC ~25.8mVAC ~52KHz
R322: 000.0mVDC ~28.0mVAC ~52KHz