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Marantz 2238 won't power on.

I got impatient... I tested the output voltage from J809 and J813 = 8.26V AC. Seems reasonable. I resoldered back pins J812, and J813. I had previously taken all the bulbs out as they were burnt out. NC when testing continuity. I plugged in new LED 8V bulbs. Plugged in the unit to the DBT and powered on. Lights! :) Powered off within a few seconds. Again, I have all the other boards disconnected so I can not test sound or other functionality yet.

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So I do not think that 15244BTR is the replace zener diode for the power supply. It seems too small. I put it in and it immediately burns out. I have checked that I am putting it in the correct way. What is a good replacement for BZ-140. The 15V 1N4744 did not allow me to adjust the voltage down.
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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 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 .
Click to expand...

So I did a test with the 15V 1W zener. After hooking up J805,J806,J807. Unit passed the DBT. Then removed DBT and retesting you were right that the voltages did come down a little bit. I can now adjust Q803E to exactly 35V. But the voltages are still not exact. I still need to find a 14V 1W+ zener.

Location |Spec |New reading | J805,j806,j807 connected
Q803B | 35.7V | 38.0 V | 35.6V
Q803C | 46.0V | 49.7V | 48.2V
Q803E | 35.0V | 38.6 V |35.0V
Q804B | 15.4V | 17.9V | 16.0V
Q804C | 35.7V | 38.6V | 35.6V
Q804E | 14.8V | 17.4V | 15.4V
 
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I performed the power amp adjustments. Right channel would only adjust up to 9mV when it needs 14mV. Tested the speaker output and hooked up a known good cheap 8ohm 40W speaker to both left and right. I get sound!!!! Although I think right channel is weaker. AM/FM works, AUX works, I didn't check phono yet. Headphones work and sound very clear. I am pleased as I didn't know if anything else was "broken". I still plan to go through and recap the electrolyte capacitors and any transistors that I can replace on the other boards.

Can someone help me figure out where to get the replacement for the 14V 1W+ zener? BZ140.
Edit: Would 771-BZV85-C13113 be a valid replacement?
 
i am thinking after a quick look that is acceptable .. the original zener is rated 5 percent ..
35v is dialled in .
j808 is only going to be 600mv over 14v . this voltage is set by the zener .
q803 collector is fine as its before regulation .
i would call it job done . so long as everything is working fine that is .
 
petehall347 said:
i am thinking after a quick look that is acceptable .. the original zener is rated 5 percent ..
35v is dialled in .
j808 is only going to be 600mv over 14v . this voltage is set by the zener .
q803 collector is fine as its before regulation .
i would call it job done . so long as everything is working fine that is .
Click to expand...

Cool, I thought they were getting closer to spec, but I am new at this and didn't know how much leeway we have. I think I might listen to it for a while and see if I get any distortion. I will retest the voltages after letting it run 10 or 15 minutes.

What is the recommended order to recap the boards?
Should I start a new thread regarding recapping the other boards since the P800 board seems to be solved? I plan to document my work on this restore.
 
in hindsight you should maybe have started the thread as a restore .
you might want to start a restore thread and include this thread to it ?
a moderator would possibly be able to merge the threads together ? .
 
I have replaced the stereo and tuner lamp. Its all lit up and sounds great!!! I have tested AM/FM/Phono/Aux and Tape 2.
I want to thank everyone who chimed in on this to help me get it working. And a special shout out to Pete...

The 2238 all lit up and sounding great!

My stable. I only run the top receiver on the stack due to heat. I only powered the bottom ones on for the photo.

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