Sony MZ-G750 Recording with blank gaps. Help please.

[Rubber131186]

My Sony MZ-G750 was recording fine now in my recordings i get gaps of no recording from like 1 second to up to like 40 seconds.

Any way to fix this or is the first sign of the laser packing in? I am very new to mini discs.

Any help or advice would be good.

Thanks

[sfbp]

Your diagnosis sounds extremely probable. It's possible you can adjust your way out of difficulty. Unfortunately the adjustment is tuffer than replacing the head. I recommend you contact Jim Hoggarth (who will probably be reading this) and see about service. He runs an MD repair-for-fixed-fee deal which you can find on Ebay UK, but will probably respond to this message too.

[Rubber131186]

thanks so much much for help and i have mailed Jim. I went into service mode and adjusted the MO Write Power, I am sure i lowered the power and the blank recordings become less as i moved the hex value to full power (FF) i think and it didn't record any thing but it wrote the toc fine i think and the default value was B9 i lowered it to AB and the recordings had less blanks in it.

[sfbp]

increasing the write power will likely blow the laser and burn your disks. Be careful. Typically it's the read that needs adjusting, and since it's very small (1/10 of write) it's a very sensitive adjustment.

[jim.hoggarth]

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

[Rubber131186]

I did a NV RESET in service mode but it didn't help at all. Then i adjusted the read and write power of the laser and on 3 volts mains power it works perfect but on battery it still records with random blank spots.

After NV RESET power to the laser was by default :-

MO READ =1D

CD READ =24

MO WRITE =B9

i changed it to :-

MO READ =24 increased it by 7

CD READ =24

MO WRITE =AB decreased it by 14

works perfect on 3v so the magnetic head must be ok right? And the laser is ok too?

[sfbp]

You must do an alignment after NV reset. This is a servo system and the adjustment is essentially automatic. You made BIG tweaks in the laser power, and even small ones can be dodgy. Did you force 2131 (or wherever the magic status byte is) to FF, then?

It could well be that your power (not laser power) settings need adjusting. Quite tricky, and for some you need not 1 but 2 regulated power supplies. Best left to Jim. If you have the gear, just follow the manual very carefully. If something appears to be missing you sometimes have to refer to the predecessor(s) of the model in question. It's always assumed that you have been repairing these for years and already know all the moves of the previous models, heheh.

[Rubber131186]

yeah its 024 to FF or i would be stuck in service mode. I do all the MO auto adjustments and some times it fails and gives me a NG no good error and other times it says MO OK or Adj OK. Think its 032 033 and 034 to do the MO auto adjust tests. I had times it passed all 3 but still had gaps in the recordings. I took the cover off and the record head sits on the disk fine.

I don't have a laser meter to test the out put only got a muti meter. Jim said he could fix it for £12 but it was off ebay for £18 it was my dads and i am sure it recorded fine when he first had it but we only did some like 20 min test recording then it was in his draw for like a month then it started playing up. Don't think its worth getting it fixed. They go for about £12-20 on ebay.

Thanks for all your help.

[sfbp]

You probably need to tweak the main powersupply settings, then. My best guess. You did pretty well to figure out as much as you have. Leave the Laser Power, and after doing the main power adjust, you might try one final overall servo adjustment (same as what you did). A clue that this is the problem may be if the display is dimmer than you would like. Even if you only crank the main adjustment 1 increment (764), that may do it. The numbers that matter are (IIRC) 762,763 and 764 (page 19).

[Rubber131186]

thanks for the help i have had to try and speed learn so much its unreal like before this post i didn't know about the magnetic head in the mini disc recorder i thought it recorded kinda like a cd.

Is there any full on guides about service mode, it only says a small amount in the service manuals. There is lots of hacks out there that add extra stuff on some models and like with the euro MZ-RH1 you can change the region to US to get the 0.5mw back in the head phones.

How do these hacks come about as its not listed in the Sony service manuals?

[sfbp]

The hack is to change the :destination: country. That much is generally documented as servicers frequently have to deal with gear that comes from :somewhere else:

Don't recommend going into service mode much on the RH1. There are a ton of extra parameters to screw up (Avrin started to explore but they are many, mysterious and dangerous). And getting into S.M can wear out the rubber on the jog lever REAL FAST. Most people with RH1's retired them to use solely for uploading (since this is the only one that allows it with "regular" disks made by legacy equipment) and purchased another model for portable use playing HiMD.