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Marantz 2238 won't power on.

I was just going to post about the zener. As I had read, it was bad and the new one was on the way. I didn't see that you got it installed but maybe I missed that. I don't think anything will work right without it! Here's what I read:
"Q805 Zener diode. I have replacement 512-1N5244BTR part on order from mouser, should be here later this week."
If it's installed, do you get about +14V at the striped end?

Also I saw you used CPU thermal paste on the transistor. If it's the silver stuff, it's conductive and will mess things up! You need the plain white stuff.
 
rBuckner said:
I was just going to post about the zener. As I had read, it was bad and the new one was on the way. I didn't see that you got it installed but maybe I missed that. I don't think anything will work right without it! Here's what I read:
"Q805 Zener diode. I have replacement 512-1N5244BTR part on order from mouser, should be here later this week."
If it's installed, do you get about +14V at the striped end?

Also I saw you used CPU thermal paste on the transistor. If it's the silver stuff, it's conductive and will mess things up! You need the plain white stuff.
Click to expand...

You are correct. I have the zener on order.
The thermal paste I used was the white silicone based stuff from radio shack.
 
am wondering if someone fitted a regular resistor in place of the zener ... see if you can read the markings on it .
 
petehall347 said:
that explains the problem then ..
Click to expand...
So I have to wait until Thursday when my 14V zener is supposed to arrive. Question: I have a new 12 Volt zener in my home parts bin. Do you think it would break or blow up anything if I try that while waiting until Thursday? It is a 1N4742A 12 Volt zener diode.
 
Aaron99 said:
So I have to wait until Thursday when my 14V zener is supposed to arrive. Question: I have a new 12 Volt zener in my home parts bin. Do you think it would break or blow up anything if I try that while waiting until Thursday? It is a 1N4742A 12 Volt zener diode.
Click to expand...
Nevermind the 12V zener question. I feel its a bad idea. I just called a local audio repair store that repairs Marantz and they have a 14V zener. I will go pick it up today.
 
So I go to the shop and they only had a 1N4744 in stock. He said it will work.

I put it in, and we have much better results, but now the output voltage is on the high side. I turned the adjustment to the minimum voltage and here are the numbers.

Location |Spec | Old Reading |New reading
Q803B | 35.7V | 5.6V | 38.0 V
Q803C | 46.0V | 52.5V | 49.7V
Q803E | 35.0V | 5.03V | 38.6 V
Q804B | 15.4V | 1.2V | 17.9V
Q804C | 35.7V | 5.9V | 38.6V
Q804E | 14.8V | 0.5V | 17.4V

So that seemed to help. But the voltages are now too high. I will put the correct zener in when I receive it later this week.
 
to start with it is 15v zener .. i will look at voltages now ..
edit ..
zener seems to be operating at 17.4v ..
q803 emitter might dial in ok with r808 as it is but wait for correct diode first as j808 will likely still be a little high
when the circuits are loaded it down it should drop a little too .
 
Last edited:
petehall347 said:
to start with it is 15v zener .. i will look at voltages now ..
edit ..
zener seems to be operating at 17.4v ..
q803 might dial in ok as it is but wait for correct diode first as j808 will be a little high
when the circuits are loaded it down it should drop a little too .
Click to expand...

I was just happy to get a positive result. I agree I will wait for the correct zener before testing further. I only kept the unit powered for less than 30 seconds while measuring voltages. I was considering hooking up j812 and j814 again and testing to see if the lights work. Should I wait, or would that be ok to test?
edit...
I still have J805, J806, j807 and j808 disconnected.
 
i thought they were still not connected thats why i mentioned when its loaded voltage will likely drop a bit .
just get the right zener in there and i am pretty much it will be fine .. i know its hard to have that final bit of patience it took me many years to get nearly there . :D
 
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