MHZS CD33 distorted and clipped heavily

hi everyone

I hv owned cd33 for a few years. And i hv moded some caps before. After intalled a pair of NOS GE5670 to it today. it played normally at first.

Then after some hours, i turned it on again and it started to distort and clip
heavily.

I am sure that the tubes are normal cause i trace back the distortion to the output pin of the opamp. And i assume the opamp should be normal because i measure the rail it was 30v.

What would be the source of the distortion? :?  
Where should i test?

Last resort would be bring it to the dealer and the warranty was ended.......gonna cost me some....

many thanks~~

yep. i can read it~~ XP
I hv measured the plate voltage ~80v  should be fine. But thx anyway~~

I suspect there is bad soldering in the DAC board, cause i trace back and found the distortion came from the dac out put . (before 2 100uf coupling cap)

I was fustrated and gave up yesterday. Today morning, i opened the case and it played normally. Then i just closed the case and the distortion came back. (damn it)

So i suspect there was some bad soldering point.

thx for ur kind reply,

i think the distortion is independent of the temperature. I think the vibration caused by sliding the top plate back will make the weak soldering point fall apart.

Anyway, i will get all the joint on dac board re-solder on this weekend. (and mod it as well : )

If i still cant get it fixed, can i take it to hifi fever to ask some experienced hifi-er to help me?

thx~~