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Old 15th August 2009, 01:37 PM   #1
jives11 is offline jives11  Europe
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Default Repairing a marantz CD74

Hi,

Well I just got a CD74 from freecycle. It's black, weight a ton and I think has similar Philips innards to the CD104 I already have i.e SAA1540 based 14-bit DACs

I'd like to get it working again, it's very well made. It also has 6 phono sockets on the back ! Only 2 are the RCA outputs and these appear to have trim pots. I think the other outputs are analogue for a wired remote or some kind record sync, but interesting to see what once seemed like a worthwhile feature. However it's rather sick at the moment.

If I power the player up, the tray ejects. if I press the close button, the tray closes, then ejects again. The display never lights up nor is there any indication that the player is even on. The eject/close sounds very gritty and noisey compared the the whrrr-Ker-Klunk of the CD104 I have.

Any suggestions on where to begin or likely problems. I'm guessing this player does not share the griplet through-board link problem of the Philips ?


many thanks
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Old 15th August 2009, 07:18 PM   #2
poynton is offline poynton  United Kingdom
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As there is no display, the best place to start would be the power supply.

The caps are possibly dried out as in many CD104s.

Do the boards look the same as in your CD104 ?

Andy
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Old 15th August 2009, 10:17 PM   #3
jives11 is offline jives11  Europe
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Thanks, no doesn't look like a CD104 internally, though uses the same core chipset and transport.
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Old 7th September 2009, 06:36 PM   #4
jives11 is offline jives11  Europe
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I found a schematic on the web. Basic circuit looks like a CD104, but the boards are not the same. If anyone wants a copy drop me a line (jonathanDOTivesATgmailDOTcom)

A few typical Marantz touches ,the OpAmps are 4560D JRC duals and the DC blocking caps are two polar 100uF/16v caps back-to-back, making a bipolar.

I'll start with a cap replacement, I feel it's worth the effort, it's even heavier than the CD104. There is a video of one (!) on youtube which has US-style wooden end cheeks
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Old 8th September 2009, 08:06 AM   #5
oshifis is offline oshifis  Hungary
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I had this pretty unit for quite a long time. If you are interested in my mods (power supply, NOS, etc.) just pm me. Some pictures:

http://tube.fw.hu/internal.jpg
http://tube.fw.hu/jitterkiller4.jpg
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Old 8th September 2009, 08:12 AM   #6
jives11 is offline jives11  Europe
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Many thanks oshifis,

Did you have any problems with the unit ? Mine appears dead i.e the display is blank, no lights. the eject works but keeps ejecting when you close it. I'm going to follow Andy Poyntons advice and start with replacing the caps. Interesting player as it seems to be the classic first Philips chipset but using a different circuit layout.
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Old 27th September 2009, 08:05 PM   #7
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I would go straight to the power supply board and replace all the capacitors on there first. Remember, if they are as they left the factory, they are pretty much 25 years old!!! Check the supplies here as well, there are regulators screwed to the heatsink, I have seen the strange effects a bad supply can cause in these players!

The power supply board is a joy to work with as it is a separate module with a very hefty heatsink attached to it at the back. Me and my electronics engineer mate have worked on and modified it and probably sketched out the layout somewhere...

Get some isopropyl alcohol into the tray close switch towards the back of transport to clear out any dirt, dust and grime it has accrued over the many years of it's life...

The display runs from it's own transformer attached to the front panel if I am correct. Check the supplies here, I'm not sure what they should be on a healthy unit.

I currently have two CD-84s (they are basically the CD-74 with remote controls), one is in pieces and now being used for spares (has come in handy for try to learn the innards of this player!), the other is fully working but I am currently playing with the beast that it's CDM-1 transport at the moment to get it to read CD-Rs without a hitch.
I have it running with two LM4562 op-amps and it's very nice. Not quite up there with my CD-63SE but still, you don't see CD players built like these very often!
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