New project Marantz 2250b

NO it is the original can i use Deoxit to clean it?? It is SOOOOO sensitive you blow on it the values go through the roof on the DBT it goes from dim to bright just touching it
 
I am able to get sound out of the left channel now but there is a hum with it and it is not very clear could it be the new output transistors ??
 
Here is what i have done so far replaced the Zener diode it was bad that voltage is now 18v, then checked the voltage on the P800 board and it now is 35v, checked the voltage to the speaker terminals that is 0v, started doing the bias that is were i am having a problem the trimming resistor(R719) is soooo sensitive that i can get it to 10mv but then it will jump up to were the DBT glows when i get it back to 10mv it starts dropping after a few minutes
 
Well I had to replace that trimmer resistor it as just too sensitive and now at least it is very stable I can adjust the bias with no problem. Now when listening to the left channel there is no more hum but the sound is very tinny. I will replace the rest of the trimmers pots but i would like to jet the left channel working properly first
 
I guess i will start recapping the other P700 board should i change the output transistors after i recap the board or wait and put the old ones back first see how things are and then change them, also i recapped the tone board but i think this is were the tinny sound may be coming from on the left channel, I get 0v on the DC offset 10mv on the bias yet the sound is very tinny ( no base) i get 2.1v on the DC offset on the right channel and 10mv on the bias and this channel sounds very good,
 
i would expect things to be other way round . like real bad sound with 2.1v offset
on another note i would expect the protect relay not closing with 2.1v offset .
 
This is why i am scratching my head, being a noob i can get confusing when things work when they are not suppose too
 
Hi All, it has been a while since i was on this, sold my house had to buy another finally settled in,anyway the last time i was on i was having a issue with the left channel it was very tinny not sounding right, i used my phone to play music directly into the main in and was able to get good quality sound on both channels so i narrowed it done to the tone board i replaced the caps but still not better, there is a product on ebay a BA312 PE01 Upgrade has anyone tried this and is any good ?? If not I guess the next step is the transistors

Thanks All
 
Hi All, well I took out the 2250b just to check it out and the weirdest thing turned it on everything great sounds great, turn it off, turned it back on ( about 20min.later) NO LEFT CHANNEL checked the voltage on the speaker outputs they were OK plugged the speakers back in everything working fine. This was going on for the last 2 days, left channel on, left channel off, What gives???
Pat
 
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