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kgallen

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Everything posted by kgallen

  1. I love it when someone with a little care gets a great machine working again. So much "WEEE" shouldn't be such. Even better when it was a bargain! Good point about an MDLP disc in an SP machine too! My 530 is still working! :-D
  2. I think crippling an own technology and product like that would be more cynical than ever I could achieve! I’ve got lots of decks and I think they all output at the 0dB setting. Whilst I’m no maestro I think I’ve got quite ‘hi-if’ ears so any horrible sound I’d quite quickly pick up on. The nature of saturation of any digital signal means that if you saturate the coding you will get an instant and hard clip. Not a soft mushy clip you’d get with a pure analogue device. That’s why with a digital mixer you’d mix to around -18dBFS to give 18dB peaking headroom. With analogue mixing you mix to around 0dB assuming your audio chain had a peak handling of at least +20dB. In respect of this setting on the MD players, 0dB means ‘unity gain’. Decibel is a relative measure not a physical (measurable) unit. It means nothing on its own, you have to use it with some real world unit. Decibel against a unit, eg dBm or dBV is an absolute unit and means something ‘on its own’. Consumer line level is considered -10dBV. In your opening statement, is that -6dB actually -6dBV, which if so is possibly over-driving the input. -10dBV is 0.316V: -10dBV = 20 log(base10) (0.316/1) [or as I worked out "V". V = 10^(-10/20)*1 = 0.316] The 980 has a "rated input" of 500mV (into 47k). That translates into -6dBV. However with unity gain on the input stage analogue setting that's probably going to exceed 0dB in the digital domain, which means clipping. i.e. is your original hypothesis sensible if we're talking the same units? I'm learning/revising too so I'm not trying to be dismissive with the above, I hope it doesn't come across like that, it's not intended to! https://www.sweetwater.com/insync/understanding-signal-levels-audio-gear/
  3. Could be off the mark here, so feel free to respond! Analogue output spec is 2Vrms into 50kOhms. This is an ac spec, but the voltage is RMS, so this gives us an "equivalent heating (i.e. power) effect" as dc, so we'll use P= V^2/R, which would give us an output power of (2x2)/50000= 80 microwatts. If we convert this to dBm (decibels referenced 1 milliWatt), this is 10 log(base10) (80uW/1mW) = -11dBm. So how does the -7dB quoted above relate to the -11dBm output for the analogue outs; does the deck limit the analogue output to -7dB (-7dBm ???) because that is already over-driving the analogue output by 4dBm? Reversing the calculation, the output for -7dBm would be 200 microWatts which is about 3Vrms into 50k. The op-amps seem to have a +/-6V supply so could drive this without clipping in the output driver stage, but this is likely to be overdriving the input stage of whatever the analogue outputs are driving (the amplifier or other connected device). My analogue electronics is a little fuzzy, so maybe I've made some schoolboy errors here. What does anyone else think?
  4. And all players can play SP discs written with a Type R machine.
  5. Another aside - I notice some schematics note to use slightly different capacitor values in the circuits like that above, noted "UK" and "Except UK". Such capacitor changes would slightly alter the analogue sound as the filter characteristics are slightly modified. I wonder if this aligns with units with the "UK Tuned" badges? (Note not the case in the 980 schematic above on C143/C243, they are just reservoir/decoupling caps on the op-amp power supplies. That won't change the analogue sound. No idea why they would spec the increase to a 25V cap rather than 10V on a 6V power supply, other than for long-term reliability.) I just noticed this looking at the analogue output schematics for a Sony CDP-XE530 CD player. Example below, C807/C907 are 1.5nF in most models but 1.2nF in the UK model: Note: JB930 is claimed to have a "UK Tuned" version but the schematics don't claim any cap value changes for the UK model. Possible the "UK Tuned" variant came out later and the SM schematics don't reflect that. Sometimes there is a SM supplement (like I have for the E10). Mods - I'd like to delete the following image, but seem unable to...
  6. This is the analogue I/O section if you wanted to check the +/-6V rails from IC141 and IC241. Unlikely to be wrong I know, but as you appear adept enough with you test-tone stuff I'm thinking you're up to this check! This looks like fixed gain buffer stages so any attenuation control will be in the digital domain prior to the DAC. (As an aside, for anyone who is interested in electronics, there are some nice simple op-amp configurations here that one could analyse and research - unit gain non-inverting buffers/followers (around IC101), differential to single ended buffers with stability compensation (around IC111) and active low-pass filter around IC112.)
  7. I'd agree that does sound weird and I don't really have any other ideas at the moment. Clipping in the analogue world (on a well designed circuit) is usually due to inadequate power supply headroom (power supply rails too low). I'll need to take a look at the schematics. Do you think this is a new phenomenon or that you've only just noticed it? Does the 980 support SF (Scale Factor)? Probably not relevant as I read the above that you used "monitor" mode in your testing and I don't think SF would affect this.
  8. I expect that will be mostly Play rather than Record hours. Play uses a very low laser power. It's 10x at Record. I suspect there are plenty of hours life in your deck yet. I'd hate to think how many hours are on my 520. As we've been discussing widely on other threads recently, a replacement drive is an easy to swap and with a little luck, a low end deck with the same drive can be had for sensible money.
  9. Go for it, it it's convenient! Then we can compare and contrast and see if yours is doing anything out of the ordinary!
  10. Have you tried with different discs? If the disc is heavily edited or was scratched/dirty at the time of recording then the data could be fragmented causing the mech to keep reseeking for the next chunk. Try a new from the packet, or if needed a fully erased disc and see if it still happens. I'm not sure any of my mechs are fully silent (with the lid off). Some are definitely more clicky than others and some discs definately worse than others.
  11. These look interesting for the ribbon cable style. They are 1.0mm pitch. For MDM7 drives, 27 core and 23 core cables are needed (neither of which are on this listing) with "forward" contacts depends on the machine. https://www.ebay.co.uk/itm/0-5mm-FFC-FPC-Flexible-Flat-Cable-Ribbon-4-6-8-10-12-16-18-20-24-26-30-32-34-40P/143053978948?hash=item214eae7d44:m:msRnpKBebcuZOCrMN4r_6ug Having had a good search of eBay I can't find any 23 or 27 way FFC ribbons. I've found some 7 way for the IOP test jig cable so have ordered a couple of styles of those to see what might fit. ETA: I did find the required 23P and 27P ribbon cables after contacting the seller - see my linked post below.
  12. I think they use an off-the-shelf JST connector, so maybe. For the ribbon cable, different lengths and folds are used in each machine and some might need the exposed contacts on opposite sides when flat due to the fold. The folds are the cause of the "reverse numbering" that was reported on one of our recent threads. I'm going to have a look around for these ribbon cables because I want to make an IOP jig for my MDS-E10/E12 machines. On the MDM7 they've changed the JST GH1.25 6pin (as on the MDM5) for a 7pin version of this flat ribbon cable connector. ps So far so good with the 530! Suitably enthused I've pulled down my problematic E10 again in the hopes of a breakthrough. I can confirm this one isn't down to the ribbon cables (or the MDM7SC)!!!
  13. Absolutely! That’s the power of community! :-D
  14. Yea...! So far so good this morning!
  15. Still looking promising! I just took both ends of both ribbon cables out (MDM5 was out of the chassis as the connectors are underneath) and then reassembled it. Totally surprised when one after the next disc tried read perfectly. So no, I didn’t use any solvents. I can’t believe I’ve not done this before I’ve had the machine for a few years - it was the first I’d bought since 2000 (?) when I bought my MZ-R700 portable. Let’s see what tomorrow brings! Even my wife says she’s sick of seeing the inside of this particular machine, so I’m hoping it really is fixed!
  16. Fingers crossed the 530 is behaving so far. Just done a bunch of track divides on one of the MDs I dubbed from cassette last week so played/FF and done a number of TOC updates. Read fine in my MD-CD1 where I’ve just titled it up. Sounds like we’ve all had a decent day!
  17. Well at the risk of speaking too soon... and despite all of the mucking about above it’s possible the only problem was oxidised ribbon cable connections!
  18. I’m getting cocky now. Stevie Wonder’s Secret Life of Plants, couple of quid from the second hand shop. Double CD. So my first LP2 in the bag now! (Dubbed from 2 CDs in LP2 using my Tascam MD-CD1 then track-labelled very quickly using PS/2 keyboard). And as a bonus I got my hair cut too ;-D (see my earlier post if you don't know what this is all about...!)
  19. On the stuck disc issue I’ve had this lots of times trying to fix various decks (pain of well documented here!). As ever the main thing is not to force. Depending on the drive usually you can get a finger onto one of the gear wheels involved in disc load and rotate it bit by bit with a finger to eject the disc. My experience is with the MDM5 family of drives (520,530 1998-99 type vintage) and the MDM7 family in my E10/E12 and x40/x80 ranges we’ve been talking about more recently. MDM5 can be done in-situ as there isn’t a belt and all the gears are clearly accessible at the rear of the drive.
  20. ...and my 530 has just read 4 for 4 discs first time having removed the drive and reinserted the ribbon cables. ok so tomorrow it will probably refuse to read again. If it behaves we could be on to something here chaps...!
  21. Great news! It’s quite possible a ribbon cable connection oxidised over the years and the act of withdrawing and reconnecting them cleans them up sufficiently. So much so that after typing this I’m going upstairs to do just that with my errant 530 because I’m not sure I ever did the same! On your initial survey it would be interesting if the same subset of discs read and the same set don’t or whether reading was just generally intermittent. It’s great the JB drive is working in the 470. Give it a good soak test. Then check again tomorrow! (Because with my 530 I’ve thought it all working only to find the following day it doesn’t!).
  22. It was only a few months back. Just prior to the Techmoan MD revival I think! :-D
  23. Indeed! Not much use for music I understand, although with a Type-S player apparently LP4 can be quite acceptable. Prior to my more recent spate of desk acquisitions I only ever had my trusty MDS-JE520 from new, which is just prior to Type-R and MDLP, so I never really got into LP2/LP4. All of my discs prior to this story are SP. At least my MZ-R700 portable at work is MDLP so I’m game on for the audio books now! I’ll be paying more attention in the dusty back sections of Charity shops from now on!
  24. Absolutely! I bought my 480 for £9.99 as a ‘broken’ donor deck, but it just needed a belt, so it works now too... And actually it’s my only Type-S deck!
  25. Great story, so glad you have both of your machines working now! Also I think you’ve found your way around your machines a bit so I think you’ve learned a lot. Same for me - 18 months ago I didn’t know an MDM from a... mmmm Malteser! Kevin
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