Rubbertoe81
Member
I recently purchased a non working ta1055 integrated amp.
Upon testing I realized a couple of output transistors were cactus so I replaced all 4 of them with new tip31c transistors, I also went through and replaced the uni watt driver transistors with bd139 & bd140 pairs.
When tested all looked fairly good initially,
I measured around 2mv dc at the left speaker terminal but around -90mv on the right channel.
I hooked up my sacrificial speakers and powered up, I immediately got clear audio on the left channel however the right channel was silent for 5-10 seconds after power up then the audio signal came through.
After disconnecting the speakers and reconnecting my dmm I realized that when powering on I am reading around -2 to -3 vdc for around 5 seconds before it jumped to around 1vdc for a second them balances out and remains stable at -90mv.
I did also replace the differential transistor pair with a closely matched pair of ksc1845’s but this made no difference.
Any ideas what could be going on here?
Upon testing I realized a couple of output transistors were cactus so I replaced all 4 of them with new tip31c transistors, I also went through and replaced the uni watt driver transistors with bd139 & bd140 pairs.
When tested all looked fairly good initially,
I measured around 2mv dc at the left speaker terminal but around -90mv on the right channel.
I hooked up my sacrificial speakers and powered up, I immediately got clear audio on the left channel however the right channel was silent for 5-10 seconds after power up then the audio signal came through.
After disconnecting the speakers and reconnecting my dmm I realized that when powering on I am reading around -2 to -3 vdc for around 5 seconds before it jumped to around 1vdc for a second them balances out and remains stable at -90mv.
I did also replace the differential transistor pair with a closely matched pair of ksc1845’s but this made no difference.
Any ideas what could be going on here?