Player had stopped reading discs - I recallobrate the laser - here's how

Crocodile JD

Active Member
Warning::lesson: Firstly let me say that I take no responsibility if anyone follows this, they do so at their own risk. Both in terms of damage to the player or injury. Note that even with the mains plug out, if the power has just been turned off, a heavty charge is still present in the capacitors on the power board. Before attempting any calibration the player should be unplugged and I would strongly recomend leaving it 5 minutes or so for the capacitors to discharge. Also be aware that damage to electronics can occur due to static transfer from your body so try to ground your self by touching something that is earthed before you start and don't drag your feet on the carpet!

A question of economy: My player is a Harman Kardon DV2550s (Same as the DV25 apart from colour). I bought it new for £250 but decided that it would be too costly to repair, as it was £50 minimum charge just to send it and have it looked at plus what ever the repair would cost. So given that prices on new players have fallen since then, it was fix it or bin it! If your player is a £500 player it is most likely worth sending it for repair.

Symptoms: Over a period of a couple of years, the player got more and more picky about which DVDs it would read until it finaly gave up bar one favourate DVD (Ice Age 2). I understand this to be a common problem with these and other players. Apparently, over time, certain components loose a little power or the calibration slips, but the difference is enough to upset the fine balance that allows the laser to distinguish Ones and Zeros in the data. I'm sure there are many articles across the web if not this forum on the technical ins and outs of optical readers and possible faults, but this is my personal account of my very crued approach.

On to the nitty gritty: On taking the lid off, I found that the disc loader in my player is a Sanyo and I was lucky in that I could see the laser lens and the calibration potentiometers (pots) without having to move the laser mechanism out along its track, you might have to move it to see it. My player had 2 pots, 1 for CD and 1 for DVD. Some have just 1 and a few even have 3. Sometimes I believe they are identified, but mine were not so it was trial and error. I should have taken a picture, but they are little square components with a circular bit in the centre on a small PCB adjacent to the laser lens. There is usually not much else on the PCB so they should be conspicuous. they are only about 3 or 4 mm across and they are very delicate. I used long nose plyers and I have damaged the rotational outer bit on the pots but fortunately they still work. I would think that there are proper tools to make these adjustments and a magnifying glass would have been useful too.

Lens Cleaning: Before attempting calibration it is probably worth cleaning. My player wouldn't play lens cleaning discs but if yours does it is worth a try before doing anything else. If not then with the lid off clean the lens with a cotton bud and some CD cleaning/lens cleaning fluid. One quick wipe and leave it to dry for 3 or 4 minutes is enough.

On to the calibration: If that doesn't work, it is time to start messing if you want to take the risk. Armed with the last working DVD, a notoriously difficult DVD and a CD I set to. On my player it turns out that the CD pot was on the left and the DVD pot on the right. I found out by process of elimination that the left hand pot was the CD pot. This is because, on tweaking, there was no change to DVDs (good one worked, bad one didn't) butCDs which prior to my messing were working properly, stopped working. I had tweaked the left hand pot initially in a clockwise direction. So I tweaked it back anti clockwise and CDs started working again. On to the right hand pot. I tweaked this anticlockwise based on my experience with the CD pot, to find that previously working DVD had now stopped working, so clockwise was obviously the way to go. I got the good DVD working again by returning it to its previous position and eventually after about 5 clockwise tweaks(remember that I was powering off after each attempt) I managed to get the bad DVD working for the first time in a long time. In all I don't think I went more than a quarter or third of a turn. So remember it is only tiny tweaks that are needed.

Finally: I put everything back together and gave it a full work out and it played everything I threw at it. I don't think the pots can stand any more of my hand fisted approach, but at least the player is working .:clap:

I'm sure that with the right pot adjustment tool, I could have effected the recalibration perfectly. A task that many will have payed alot of hard earned for in the past. I'd speculate that many have payed for new laser units or even complete loaders along the way, unnecassarily (whether they were even fitted or not). Either that or another player dumped and a serious bout of upgraditus!

Good luck
Croc:)
 

sparticus

Active Member
Well I guess you have discovered the tweak then. I haven't known anyone to do it without a multimeter and a pot trimmer though. Still I always admire someone prepared to have a go.

It only works for a while though as the new, much higher laser current usually burns out the laser even quicker than before. Could be time to sell it. Really there is no way around the fact that the laser is stuffed. Good luck with it though.
 

Crocodile JD

Active Member
Hi Sparticus

The player showed signs of being temperamental from an early age so is it possible that it was always just badly calibrated from the outset? Although there has been an obvious worstening over time.

Croc
 

sparticus

Active Member
Yes mate perhaps you are right. Although a lot of manufacturers use lasers that are a bit marginal to start with. Ive had to look at loads of Denons for instance and they seem to be pretty shaky at an early age. Sometimes you can adjust the laser current to make them better and sometimes not. I think its unlikely people are being charged for new lasers that dont get fitted though. Sometimes you can tweak these and two months later the customer is banging on your door again. Its often easier to fit a new laser, and not see the thing again. I hope you get lucky though as it isnt as if you had much to lose, and as I say, I always admire someone who will have a go. Its not as if its dangerous or anything and the more you do, the more you learn. Just for info you can sometimes find the same laser in many different products. The transport can be different but sometimes the laser is the same.
 

Crocodile JD

Active Member
I don't suppose you know what is in the HK DV2550s by any chance. I know the Loader is Sanyo, I did write down the only code/serial type numbers I could find and google them but drew a blank. I couldn't see any reference on the laser assembly. If thought I could get an ecconomical repair I would still contemplate it.

Croc
 

sparticus

Active Member
I havent seen inside a HK so wouldnt know. If you know anyone with a sanyo dvd player or drive you could take the lid off and have a look. The numbers wont mean much except to Sanyo. You need to start a collection of broken dvd players! Whats in your PC?
 

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