jim.hoggarth

You don't give much to go on, but there are two immediate things coming to mind. If the message appears when first plugged into the USB port, it may be that the disc read is failing. Does a similar problem appear when inserting a disc for playing, when not attached to the PC? I have also had a similar problem when using any Hi-MD unit on a flaky USB port. Some USB sockets just don't work right. You seem to be saying you have already tried a different USB port. Have you tried a different USB hub (often two USB ports on the PC will be the same USB device, so try the ports on the back of the machine or a separate plug-in hub).

The coil has a DC resistance of 3.6 ohms if I remember correctly, but take it from me the coil is not the problem. The flexible connector that feeds the head has cracked. It is a common problem on certain models, mostly the N1, R700 and G750, but the N505/707 are also susceptible and a few others. If you remove the upper casing (four screws, two each side) it should be immediately obvious to you. Needs to be replaced, or some say it is possible to wire across with flexible wire such as headphone cable core. Personally I replace, as I feel there may be problems down the line with earphone cables. Jim

4manpop - that is a typical problem with the fakes that can be found coming out of China. Usually they are too long. Even if they do fit, the maximum capacity is often way below that which is quoted and which a genuine Sony would provide. Some decent non-Sony batteries are made by Vapex and GP. Try searching for these, or send me a PM and I may be able to supply you direct with a second-user, but still perfectly adequate, battery. Jim

I have just left the guy a comment telling him what's wrong. Jim

Please see the comments I have just left re the RH1 in this thread: This should explain the two possible causes of your problem Jim

Mainly mechanical - the unit is just not built to survive actual use. It all looks very pretty when you first get it out of the box, but it quickly starts to show its faults. Here's a few examples: 1) The jog dial is a laugh. These switches were bad enough when used on the likes of the R90/91. At least in those models you could get to the switch to clean the contacts. The RH1 has the big plastic extrusion that is the jog lever that makes it very difficult to get at. The jog lever also breaks off too easily. And the miniature switches used for group, vol+/- etc were crap when they were used in the N910, so why use them again in later models? Every second N910/920 I see has a faulty End Search button. 2) The upper metalwork (ie disc lid) is prone to bending into a convex shape. This causes disc-in switch problems until the metalwork is bent back. I assume this is due to folk putting it into a back pocket. True, Sony advise not to do this, but then people are people. 3) In a similar vein, the plunger that operates the disc-in switch does so through a sprung metal tab, underneath which is a stuck-on plastic spacer. I assume this is a post-design modification to fix a disc-in switch problem discovered after the design was finalised, as there seems no obvious other reason. Which would be fine, if the plastic spacer did not slip sideways under the pressure of the plunger, causing it to come of eventually! So yet again, the unit keeps resetting itself. 4) The OLED displays are nice but everyone knows they fade with time. So what do Sony do? Put two of them in. 5) The display/switch 'block' is a plastic lump which hangs off the metalwork by three small tabs. In order that the display can actually be seen, this plastic needs to be a translucent type (is it a polycarbonate??) Unlike say ABS, the display plastic is brittle and it's not long before the three tabs break. The result is at best a loose display block. At worst it falls off. 6) The connector from display block to main board is bent to such a ridiculous extent, that removing the display block just a few times can cause the connector to crack and require replacing. I have never liked equipment that is NOT built to be serviceable. 7) The USB connection is flaky unless the board screws are fit with a torque wrench (Seriously, this one is even in the service manual) 8) The plastic end cheeks on the lower case are simply held on by melting (mushrooming) plastic pegs. This is a common technique, but not when you only have two plastic pegs to mould. Ten, twenty, yes - but not two. It only takes one to break, and the second peg follows. And then the plastic part just drops off. I hope I have not put anyone of buying an RH1. Just make sure you super-glue it to a brick before you try using it, and put it in a box so you are never tempted to use a switch or change a disc! Jim

Totally self-taught, building on my previous experience as both a bench and field engineer in the office equipment and computer trades. It has taken me over eight years to learn as much as I now know on MD units, and I am still learning (just today I gained more insight into a certain Aiwa unit). It's not just the dry facts, but getting to know the faults and fixes needed, the best procedures, and the quick tricks. For instance, I can now diagnose some faults just by the noises that the motors make. or by a pattern of fault codes. I will never stop learning, I hope. Jim

Thanks for that Stephen. I have been meaning to do this myself, since I had an AM-NX9 returned by a customer because it would not work on W7. Jim

It's not easy to tell from the photos, but it looks like the write head is beyond repair. I have had heads twisted to a lesser extent, and despite trying to bend it back into shape, it still does not perform 100%. Luckily the heads are fairly easy to obtain as loads of units with this drive were discarded due to the eject in/out and grinding gears problem. The JE320 has the same drive unit as the MDS-JE510, MDS-S38 and MDS-S39. These are the most popular units that will be found on sites like eBay. The big problem is that replacing the head on this model of drive is not as easy as with later models, and requires a major strip down of the drive unit. And in theory, once the head is replaced, the drive requires alignment but in most cases you will get away without it. My one concern would be that it is *very* easy to do further damage to the drive unit through disassembly and subsequent rebuilding. Now I may be able to supply a head, but I'm not too keen to spend hours explaining how to fit it, to be honest. Where abouts in the world are you? Jim

That depends on the model, for a couple of reasons. One is parts availability. The other is my deep hatred of the MZ-RH1. I don't like trashing Sony and especially MD units, but the RH1 is an absolute bag of &!@[. If you push me I will let you know why. Please PM me if you need help. Jim Indeed I am! Never had fans before! Anyways, I am glad you have given that unit a good test Jim

Hi y'all. Actually my listing is down because eBay have taken it down. They say it breaches their policies. And they also want me to put any rewritten version in one of their 'Other' sections, which means nobody will ever see it, so I have temporarily removed it to see how much work I get just by word of mouth alone. Ok, the NH900. I have discovered a few problems with this unit. I can confirm the Stop button problem; for some reason just this button is affected usually, occasionally a few others, and it is simply down to the switch contacts that need cleaning and 'brightening' to prevent the key value being misread. I have also discovered that the NH900 is prone to not charging batteries properly. It will cut off charging early, resulting in a battery with a low capacity. It is spurious, and I have not yet managed to determine a real pattern. Part of the reason for this is I have such a small sample of machines to test, with only two in stock and having just worked on a couple more customer's units. I have adjusted the voltage settings in EEPROM, but this appears to have no real positive effect. Still the problem persists, although possibly not as bad as prior to adjustment. The solution I have suggested to the guy who sent me an NH900 showing this problem is to to 'double-charge', That is, to let the unit charge the battery once, then take it through a second charge cycle straight away. It seems to get around this problem. (An interesting point: I discovered two of the NH900 voltage settings were 200mV out compared with the printed values in the service manual. I find this suspicious, and wonder whether the values in the manual are incorrect: a misprint?) As for jmsla's original problem, I suspect they need both voltage and mechanical adjustments, and may even have faulty optical pickups. This is actually a very common problem with the Hi-MD units I have seen so far, and in many cases there is a perceived fault on the optical pickup that alignment will not cure. To be honest, I would have to see the unit(s) before knowing for sure what the problem is. I would also welcome the ability to add to the sample of NH900s I have seen in the workshop. So you need to PM me, so we can arrange that the recorders can be posted over the pond to me here in Blighty. Jim PS - I have started to develop a simple web presence based on the gratis www facility provided by my ISP. At a later date I intend purchasing my own internet domain, but that will come when I have created a sufficiently decent web presence on the free option. Hopefully I can get Google's spiders to crawl on it soon, so I can be found with a Google search such as 'minidisc repairs'. I am adding a few paragraphs every day, hopefully it will be functional in a week or two. So the temporary home is: http://www.angie0310...ueyonder.co.uk/

Hmm... The skipping problem is symptomatic of a faulty optical pickup in the R50, that is for sure. Recordings made prior can seem fine on many units, and then one day the R50 just starts 'stuttering'. I have done this myself, using my numerous and varied test discs for Hi-MD recording, and then cleared them down for reuse as legacy MDs. But I always use an old deck for disc erasing as they do not baulk at NetMD recorded tracks that are marked as protected, as their firmware was written prior to the concept of NetMD. That said, I have seen a number of R30s giving this fault recently (same basic hardware and optics), so there may be something in it. I will, given time, do some experimenting. It would be worth my while as if this is a genuine phenomenon I will want to segregate my legacy vs. Hi-MD formatted MD80 discs. Jim

Hi Xircuits I am really digging deep into my fading memories here, but I am sure I have had this on either the MZ-N1 or the MZ-N707. Turned out it was a fault on the USB connection of the MD recorder's main board, requiring a main board swap. Further to this, I am certain I had another MZ-N1 in for repair showing that sort of fault, here the owner had cleared down the EEPROM memory. Now reinitializing the motor and optical control settings is not a too difficult task, but I had no way of resetting the USB stuff. I assume the EEPROM holds an encryption key unique to that machine, but I do not have the Windows software needed to work with the firmware this way. The solution again - swap in a known good working board. I realize all I am doing here is giving you a glimpse into the problem, but no solution. Ultimately you may need to try the NetMD recorder on another PC as you suggest, preferably with a good copy of Windows XP. Also if you could let us know what make/model of NetMD recorder you have it may help. Jim

Hi folks - thanks for the off-site heads up Christos, I missed this originally. This is caused by another of Sony's brilliant design cock-ups. The N910 was a transitional unit, from the old N710-style chassis and pickup/motors to the newer Hi-MD style chassis/motors/pickup. But, the intermediate sled transmission gear on the N910 is far too large in my opinion. Indeed, later models had a similar motor chain design but the sled motor capstan was made larger and the transmission gear smaller. I assume, because of this problem. During fast track seeks the big gear must hit some resonant frequency with the result it vibrates like hell. This only happens in one direction, because the force of driving the sled shaft helical gear causes the sled transmission gear to lift in one direction and fall in the other. Frictional components are presumably different in these two positions, hence it only resonates on the 'outward' journey to the higher tracks (this is from memory, so it may be the other way around!). The correct solution is to replace the sled gear with one with a different resonant frequency. I would assume some drastic action such as removing a small amount of plastic from the gear would have a similar effect, although I have not attempted this (I may just try now, perhaps two small holes drilled at diametric opposite positions). The other solution, which is quick and easy but not really ideal, is to add extra drag to the gearing chain. A minute smear of silicon grease does just this. I grease the part where the transmission gear drives the helical shaft gear. BUT - be aware that too much grease and you can hear the loading effect as the gearing mechanism starts slowly and gradually speeds up. A case of less is more. Jim

Yes, although I have not actually compared down to the last component. But if you take a 780, put it in a taller casing, screw a metal plate to the top to make it heavier and fit gold plated RCAs, you have a 980. On opening my first 980 I was severely disappointed to not even find a toroidal mains transformer in there! Jim PS, for Nick (fourbanks) and a blatant sales plug: if you are interested in one of the above decks, I definitely have an MDS-JE640 tested and ready for sale (once I have replaced the eject drive band I pinched off it last week). Just email me as normal.

At a guess you have a problem with the spindle motor - ie the motor which spins the disc. As the laser moves further out to the edge of the disc, the motor needs to rotate more slowly to keep the data rate the same. I am guessing the motor, or possibly the servo unit driving it, cannot produce the slower speed required without causing tracking problems. Or it could be the laser unit not properly aligned. Where abouts are you in the world? Jim

I will let you know when it arrives! Just bought it. It's worth the money just for the battery contacts, assuming they are any good. Decent battery terminals for R90/91, R900/909, N1s etc are getting really hard to find. I wish folk would stop leaving batteries inside their units - at this rate I will be replacing terminals with bent paper clips !! BTW, slugbahr, noticed your signature. I have in my possession one brand new MZ-RH710 which I intend selling soon. Only problem, it is Piano Black not Silver. Let me know if you want it, in other words make me an offer Jim

Interestingly, I have an NH900 in at the moment which is displaying charging problems. Very finicky about what battery is in, and even successive charges can differ on the same battery. As it's not a simple fix I can push out quickly, it's been in a few days now. Hopefully soon, a bit of experimentation with the voltage settings may help the problem. If I can ascertain anything concrete I will report on it further. I may also have other NH900 units in stock which I can use to qualify my findings. Jim

I have replied to your PM, Rubber131186. For the sake of all other readers, please don't mess with the laser power or you may damage the laser diode permanently! Jim

You are probably throwing good money after bad. If the head was dirty, I would expect some data to be written and playback to be intermittent. But it looks like there is no write signal to the head, or more likely the head is absent. A common problem with the disc drives in the JE510 is the head being ripped off, or just mangled, by an incorrectly loaded disc. Or in some cases the drive is stripped down to attempt a repair or modification (such as are found on the web), and the head is damaged on rebuilding. You could try taking the top off and photographing the drive unit from above. Post it here and I can quickly tell you if the write head is damaged. But I would put a claim in straight away with eBay as it is not as stated - assuming it was not sold as 'for spares or not working', of course. Jim

According to the MZ-NH1 user manual, 60 minutes for 80% charge. If left in the charging dock for a further 2 hours, the battery is trickle charged up to 100% capacity. I personally have never seen more than 'CHG: 65 mins' on the screen of an NH1. I assume the RH1 takes the same length of time. The differences in mains adapter should have no effect. And a double charger unit? I know of no external chargers for these batteries, not even for one let alone two. Jim

Hi Imran, Stephen et al. Just checked the N710 service manual and I can see from the circuit diagram that the external DC inputs and the AA add-on battery are effectively in parallel. The internal NiMH battery, however, is connected directly to IC951, the battery charging control IC. I would guess the likely culprit is this chip. So presumably the recorder will need a board replacing. I will contact you via Personal Message, Imran Jim

That's a rare problem on the R700, and something I would not expect to see. The most likely culprit is a bad joint somewhere on the main board, or the chassis is bent slightly and the disc-in switch is 'flickering' as the top case is moved. Has the unit been sat on? Usually this results in a cracked LCD unit too. Another possibility, if it only happens when run from the battery rather than the mains power adapter, is the contact between the positive terminal under the battery flap and the circuit board. This is done by a peculiar 'finger' to one side of the battery terminal under the flap. If this is dirty there will be intermittent contact, of course. If it is bent too far forward, contact will also be problematic, Roughly, the 'finger' should be in line with the centre of curve of the contact plate. You should be able to make out the metal strip (half-round shape) with which this finger makes contact when the battery door is closed. Let me know how you go on. Jim

Still here Stephen, just lurking as you say. Not a lot to respond to recently.... Jim

I have had similar faults occasionally in the past with faulty units I was working on. I seem to remember it happens when the disc is being written/verified, and could be something to do with a fault on the recorder itself. I can't be 100% sure, but a cracked write head cable may have caused this. If this is the case, you will also get problems recording from an analogue source. It may be worth trying a fresh or empty disc and recording a complete 80-minutes-worth via the line or optical input. If this succeeds 100% with no failures or an empty disc at the end, then it is not that problem, so you can at least eliminate it from the list of possibles. Don't automatically assume it is the USB connection, PC, a virus or SonicStage at fault, especially if it was all working ok before. Jim