Way back in the day I owned it's little brother the SD-3000. Arrived home from work to find someone else now owns it along with a very nice Pioneer PL-514 and other stuff - rule 303 needs to be applied.
Fast forward 30 years and I bought myself a nice SD-4000. Apart from 2 very small marks it's in excellent external condition but has a few internal problems.
1 - This deck looks as if it has never had the tape path cleaned. It was filthy but with the careful use of air chisels, power files and angle grinders I soon had the heads looking like new. Finished off the job with a quick wave of the DeMag.
2 - REW and Auto Stop not working. The deck still had it's original belts so I ordered a set of belts from Wagners, gave the pulleys etc a good clean and the transport is now working perfectly - or so I thought. More about this later.
3 - Occasionally the RH meter would go full scale with a corresponding THUMP in the Right speaker. A bit of searching found a piece of broken ferrite stuck under transistor Q252. I crawled all over the deck looking for broken slugs etc. All looks OK so I've no idea how it got there. Doesn’t seemed to have caused any permanent damage so we can call that fault fixed.
4 - No record RH channel. Fed a 1Khz sig into both channels and went hunting with the CRO. It didn't take long to find the prob - no Rec Bias in the RH channel. The 1Khz sig is finding it's way to the RH Rec head so that rules out any probs with that part of the circuit and the LH channel is working perfectly so the Osc is running OK.
That narrows it down to the Rec/Play switch and a few components that connect the Osc to the switch. 47K Trim pot, 3.3K 1W resistor and a 100pf cap.
The Rec/Play switch was my main suspect but after much poking, prodding and appropriate/inappropriate language while watching the waveform I'd all but ruled it out. Time to go hunting with the CRO again and the moment the probe lightly brushed the leg of the 3.3K resistor the bloody thing burst into life and no amount of tapping, hitting, wiggling, appropriate/inappropriate language was going to make it fail. The waveform on the CRO was 100% rock steady - WTF
Connected the deck to my back-up amp and media player, inserted a blank C90, turned the balance fully to the right, pressed REC and let it record for the rest of the day, turning the tape every 45 minutes. Because this deck has separate rec/play heads if it stops recording I'll know straight away - never missed a beat.
Powered it up the next day and you guessed it - no rec RH channel -aaaarrrgghh
OK what happens if we put the probe on the other leg of the resistor?
Again the bloody thing burst into life and no amount of etc etc etc.
What followed was a week of testing and during this time the deck functioned perfectly so I bolted it back together and wired it into my main stereo.
BUT, just to prove that Murphy is alive and well - see point 2 above.
The instant it was back in the cabinet the Auto Stop on REW (which had been functioning perfectly) stopped working - sigh
It's working 100% on Play and FF so I don't think I'll worry about it.
All of this was about 4 months ago and the REC is STILL working perfectly, I guess that there are some things in this universe that us mere mortals are not meant to understand.
Marantz didn't put much thought into the layout of this thing and servicing this board (P900) is a major PITA so I'm glad that I didn't have to change any components - yet. Famous last words.
After suffering through all of the above I'm very pleased with the end result and I now have something to play all those high speed tapes I made 30* years ago.
BTW - don't use air chisels, power files and angle grinders to clean your tape paths.
Fast forward 30 years and I bought myself a nice SD-4000. Apart from 2 very small marks it's in excellent external condition but has a few internal problems.
1 - This deck looks as if it has never had the tape path cleaned. It was filthy but with the careful use of air chisels, power files and angle grinders I soon had the heads looking like new. Finished off the job with a quick wave of the DeMag.
2 - REW and Auto Stop not working. The deck still had it's original belts so I ordered a set of belts from Wagners, gave the pulleys etc a good clean and the transport is now working perfectly - or so I thought. More about this later.
3 - Occasionally the RH meter would go full scale with a corresponding THUMP in the Right speaker. A bit of searching found a piece of broken ferrite stuck under transistor Q252. I crawled all over the deck looking for broken slugs etc. All looks OK so I've no idea how it got there. Doesn’t seemed to have caused any permanent damage so we can call that fault fixed.
4 - No record RH channel. Fed a 1Khz sig into both channels and went hunting with the CRO. It didn't take long to find the prob - no Rec Bias in the RH channel. The 1Khz sig is finding it's way to the RH Rec head so that rules out any probs with that part of the circuit and the LH channel is working perfectly so the Osc is running OK.
That narrows it down to the Rec/Play switch and a few components that connect the Osc to the switch. 47K Trim pot, 3.3K 1W resistor and a 100pf cap.
The Rec/Play switch was my main suspect but after much poking, prodding and appropriate/inappropriate language while watching the waveform I'd all but ruled it out. Time to go hunting with the CRO again and the moment the probe lightly brushed the leg of the 3.3K resistor the bloody thing burst into life and no amount of tapping, hitting, wiggling, appropriate/inappropriate language was going to make it fail. The waveform on the CRO was 100% rock steady - WTF
Connected the deck to my back-up amp and media player, inserted a blank C90, turned the balance fully to the right, pressed REC and let it record for the rest of the day, turning the tape every 45 minutes. Because this deck has separate rec/play heads if it stops recording I'll know straight away - never missed a beat.
Powered it up the next day and you guessed it - no rec RH channel -aaaarrrgghh
OK what happens if we put the probe on the other leg of the resistor?
Again the bloody thing burst into life and no amount of etc etc etc.
What followed was a week of testing and during this time the deck functioned perfectly so I bolted it back together and wired it into my main stereo.
BUT, just to prove that Murphy is alive and well - see point 2 above.
The instant it was back in the cabinet the Auto Stop on REW (which had been functioning perfectly) stopped working - sigh
It's working 100% on Play and FF so I don't think I'll worry about it.
All of this was about 4 months ago and the REC is STILL working perfectly, I guess that there are some things in this universe that us mere mortals are not meant to understand.
Marantz didn't put much thought into the layout of this thing and servicing this board (P900) is a major PITA so I'm glad that I didn't have to change any components - yet. Famous last words.
After suffering through all of the above I'm very pleased with the end result and I now have something to play all those high speed tapes I made 30* years ago.
BTW - don't use air chisels, power files and angle grinders to clean your tape paths.
