Marantz CD74 laser trimpots

westerndigital · 24th October 2007, 02:12 PM

Does anyone know how to adjust any of the laser trimpots on the CDM1 board for a Marantz CD74? I have read a <a href="http://www.diyaudio.com/forums/showthread.php?s=&threadid=67510" target="blank">related thread by drews</a> but there are several problems. For starters, Q239 appears to be a reference to the Marantz service manual. I have inspected the CDM1 board and found several transistors, but none of them is marked on the PCB as Q239. Also drews does not say which parts of the circuit he used to make his measurements of 300mV and 650mV (the ones which were too high.) Also, does anyone have the service manual for the CD74?

westerndigital · 24th October 2007, 02:49 PM

[Am reposting my first post, because the hyperlink in the first post did not work.] Does anyone know how to adjust any of the laser trimpots on the CDM1 board for a Marantz CD74? I have read the following related thread by drews:

Focus on Marantz cd74 with CDM1

However there are several problems with drews' advice. For starters, Q239 appears to be a reference to the Marantz service manual. I have inspected the CDM1 board and found several transistors, but none of them is marked on the PCB as Q239. Also drews does not say which parts of the circuit he used to make his measurements of 300mV and 650mV (the ones which were too high.) Also, does anyone have the service manual for the CD74?

oshifis · 25th October 2007, 06:14 PM

I have a (heavily modded) CD-74 and a service manual. The CDM-1 service instructions are not included, but I have a manual for that, too (unfortunately it is in Dutch). Please contact me via email.

lcsaszar at freemail dot hu

westerndigital · 8th November 2007, 07:33 AM

Thanks oshifis! I got the service manual for the Marantz CD74, as well as the .pdf files for the TDA1540/SAA7000/SAA7010/SAA7020/SAA7030 ICs. If anyone needs them I can be contacted by email using the hyperlink from my user profile.

24th October 2007, 02:12 PM	#1
westerndigital diyAudio Member Join Date: Oct 2007	Marantz CD74 laser trimpots Does anyone know how to adjust any of the laser trimpots on the CDM1 board for a Marantz CD74? I have read a <a href="http://www.diyaudio.com/forums/showthread.php?s=&threadid=67510" target="blank">related thread by drews</a> but there are several problems. For starters, Q239 appears to be a reference to the Marantz service manual. I have inspected the CDM1 board and found several transistors, but none of them is marked on the PCB as Q239. Also drews does not say which parts of the circuit he used to make his measurements of 300mV and 650mV (the ones which were too high.) Also, does anyone have the service manual for the CD74?

24th October 2007, 02:49 PM	#2
westerndigital diyAudio Member Join Date: Oct 2007	Marantz CD74 laser trimpots [Am reposting my first post, because the hyperlink in the first post did not work.] Does anyone know how to adjust any of the laser trimpots on the CDM1 board for a Marantz CD74? I have read the following related thread by drews: Focus on Marantz cd74 with CDM1 However there are several problems with drews' advice. For starters, Q239 appears to be a reference to the Marantz service manual. I have inspected the CDM1 board and found several transistors, but none of them is marked on the PCB as Q239. Also drews does not say which parts of the circuit he used to make his measurements of 300mV and 650mV (the ones which were too high.) Also, does anyone have the service manual for the CD74?

8th November 2007, 07:33 AM	#4
westerndigital diyAudio Member Join Date: Oct 2007	Marznt CD74 service manual Thanks oshifis! I got the service manual for the Marantz CD74, as well as the .pdf files for the TDA1540/SAA7000/SAA7010/SAA7020/SAA7030 ICs. If anyone needs them I can be contacted by email using the hyperlink from my user profile.

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25th October 2007, 06:14 PM	#3
oshifis diyAudio Member Join Date: Mar 2004 Location: Budapest, Hungary	I have a (heavily modded) CD-74 and a service manual. The CDM-1 service instructions are not included, but I have a manual for that, too (unfortunately it is in Dutch). Please contact me via email. lcsaszar at freemail dot hu

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