Original problem is no sub woofer output. Been through this one and recapped it and the common 2 burned 1K (R16/17)
resistors are replaced but the sub is still not responding. Volume control potentiometer is a common issue on these but
the L-R spkrs sound good.
Went by this webpage on the repair:
https://christopherbradshaw.net/The_Project_Bin/klipsch%20promedia%20subwoofer%20repair%20-%20page%201.html
On the schematic there is a sub-relay (sw101) powered by +V_HF line it
maybe is suppose to be +V_LF ? Without the relay coming on looks like the sub is disconnected.
The zeners (D03/04) that give +/- Vcc to the op amps seemed way off so I replaced them and the voltages seem much closer.
Theres also a sub-mute line on p104 to p101. Power supply shows the LF mute relay and interconnect diagram says it
gets fed from the LF amp. What is triggering the mute? I dont see a mute button anyplace.
When the speaker is connected to the 220V network, a hum appears in the bass speaker after 1-2 seconds. There are no buttons that do not work, the red power-on LED is constantly on. What is the reason, where to look for the fault?
Hi - I have a pair of KRK VXT4 studio monitor speakers. Very expensive! When I stored them, they were working fine. When I tried to use a few days ago, one of them simply hums loudly at 50Hz. I have tried replacing the two 12000uF PSU capacitors, as I found on Google that sometimes they can become depolarised but this has not solved the problem. I am trying to find a schematic for both the main board (which has the PSU and the PA stage) and the pre-amp board. - Thanks, Kevin
Hiya, am seeking a Penta amplifier circuit diagram. I have found a few on the web but this request relates to the input board. Early Penta Mark1s used an input board numbered 8002831 and used 6 transistors. my board is numbered 8002831E and looks similar - but in addition to TR1 to TR6 I have TR8 Tr9 TR10 TR16 TR16 on the circuit board. As its this board that is not working i'm quite keen to get hold of the right circuit diagram. The case says Penta 6602. Any help greatly appreciated. Happy New Year