L2 wmp12h 300watt floor Monitor

[Arbutt]

Good afternoon to you
Now I might be being a dick here. But this amp is causing me pain

It came in to me with a intermittent noise issue.
I found the fault ir9 was soldered in but leg cut short it wasn't really soldered. Replaced it.
Out the job went ok
1 month later it came back distortion after a while.
I found by heating and freezing the area around iq5 it would go away. In the end I replaced all the transistors in that area iq 1to 7 and 14. As all very close together.
All changed like for like.
Tested the amp heat and freezer it all seemed OK.

Then it went to about 1/2 volume without touching it I wasn't heating or freezing at that time was on for 20 mins before it went
When I tested it I can see its working perfectly without distortion but low output

On checking using scope and signal gen I can see the signal in and out of pre amp is OK and higher level leaving the pre amp than the input.
I'm I being a dick question
But the signal entering the power amp is at same level as the output.!!!!
Is this possible?
Check all voltages 54'v +/- and 15v +/-
Checked all the transistor /diodes
Made sure the transistors I changed are good and correct ones
At output have around 3v ac with gain /vol max
I'm not an experienced tech. Just play for fun
Any assistance would be grateful thanks in advance
Arbutt
Schematic to follow

[Arbutt]

Please bare with me struggling to get the map up loaded. I only use a phone. It says I can't upload a pdf format

Sorry it's the best I can do at present

[g1]

So set it up again so you have 3VAC going in to the power amp.
Measure the AC voltage at the following points and post your results:
IQ1 base and collector
IQ6 b & c
IQ10 b & c

[Arbutt]

Thank g1.
OK as follows using dmm on ac range. Between chassis and transistors
Iq1 base 3v collector 0v emitter 3v
Iq6 base 0v collector 3v
Iq10 base 3 .5v collector 0v emitter 3v

I hope this helps. Many thanks for the help.
I feared no one would help

[Arbutt]

Hello again
Is there anyone that can help or shed some light on this.
Too me it makes no senses.
But believe me with a scope probes on input and output both on same setting per div etc.

Arbutt

[The Dude]

Do you have both rails- +VCC and -VCC?

[Arbutt]

Hi. Yes I did. 54v +/— it's OK I have sorted it now.
Resoldered the area again. And cleaned it.
Worked for 4 days 6 hours a day. Been collected to sit about in storage �� till this shit is over


Mr a