Citrojim's AX, Saxo, Pixo, Running and Cycling Tales

Tell us your ongoing tales and experiences with your French car here. Post pictures of your car here as well.

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CitroJim
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Re: Citrojim's Skoda, Saxo, 207 and Bike Tales

Post by CitroJim »

These past few days I've done nothing with cars at all - too cold! Except drive Sally the Saxo... She's proving extremely good in this adverse weather with a brilliant heater, excellenmt demisting and a sure-footedness in the old slippery stuff :)

She really is one very fine motor car...

The new fuel pump is here but I'm deferring fitting it until she's low on fuel... She's not far off full at the moment and it's never a good idea to go round swapping pumps with such a lot of fuel slopping around...

The new pump cost £40 and is a complete unit with fuel gauge sender and all - that's good as the fuel gauge is very pessimistic at the moment...
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So instead of playing cars I'm playing vintage electronics and getting stuck into a couple of duff CD Players I have, first on the bench today was a vintage Philips CD150...
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The test gear is pretty vintage too but it does the job. That baby oscilloscope does a remarkably good job...

Having great fun :) Not quite fixed yet but I'm on my way after studying exactly how it works...

The other CD Player I have for repair I'm having some trouble locating a service manual for it... The Philips was easy but the Sanyo I'm fixing for Zel is proving very tricky to find any information on at all...

I keep trying... And I'll succeed :)

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Zelandeth
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Re: Citrojim's Skoda, Saxo, 207 and Bike Tales

Post by Zelandeth »

That ties in with the issues I had finding data for it back when I got it. I *did* eventually find one - sadly it was a victim of the Great Hard Drive Corruption of 2007 it appears.

It's a complex beast of a thing so a manual would no doubt be helpful...

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CitroJim
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Re: Citrojim's Skoda, Saxo, 207 and Bike Tales

Post by CitroJim »

Zelandeth wrote:
12 Dec 2017, 21:35
It's a complex beast of a thing so a manual would no doubt be helpful...


It will but if push comes to shove I'll just work from first principles...

Manuals used to be a luxury for me anyway but on complex things like CD Players they do help!

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Mandrake
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Re: Citrojim's Skoda, Saxo, 207 and Bike Tales

Post by Mandrake »

What is the problem with the CD player Jim ? Difficulties with tracking I'm guessing ?

Repaired a few CD players back in the 90's, interesting work if you have the service data, but ultimately sometimes frustrating when the problem turns out to be a weak laser which you can't (economically) do much about, which is what happened to a lot of them...

Those early units all had manual tracking offset, gain adjustments etc..which modern players don't have. I remember a JVC player we had had a voice coil operated lens for fine adjustment and a belt driven DC motor operated sled for coarse adjustment - so there were two nested feedback loops for radial tracking!

The first feedback loop controlled the horizontal position of the lens, but if that one got too far to the side a second feedback loop pushed the belt driven carriage along to let the lens recenter itself. Radial tracking was usually sensed by two side by side optical sensors straddling the focal point of the lens (sometimes a 4 quadrant sensor) - if the lens was too far to the left or right the signal from the two sensors was imbalanced in amplitude and gave a tracking error signal to correct it. The tracking offset adjustment would let you correctly centre the lens radially to line up with the tracks and the gain adjustment affected the gain of the feedback loops and therefore their stability and ability to lock onto a challenging disc. (Such as one with a slight offset in the centre hole)

Then there was the focus loop, controlled by the "eye" signal, (raw data from the main sensor) which basically adjusted the height/focus of the lens to get the maximum high frequency detail from the eye signal! :) (Very much like simplistic video autofocus that adjusts focus to maximise video signal bandwidth and therefore detail) It also had a gain and offset adjustment for its feedback loop.

Initial focus is found by spinning up the disc then sweeping the focal adjustment of the lens up and down through it's full range using a sawtooth drive until an eye signal is recognised then the feedback control loop is switched in to take control from that point. If you deliberately put a disc in upside down so it can't focus you'll see the lens sweep up and down about 5 times before it gives up.

We had a "test" CD that was basically just a scratched CD that was challenging to play - when all the adjustments were right most players would play it, but when they weren't adjusted right, they would skip...a good confirmation that the factory recommended adjustments were indeed doing as expected.

Even when working properly the difference in tracking ability on challenging discs from one model of player to another was huge! Some would play flawlessly a damaged disc that other players wouldn't even recognise...

Another thing you'll find is that a lot of those older players really did not like playing CD-R discs - either not at all, or they would have great difficulty with them as the reflectivity of CD-R's is only about 70% of a commercial disc, so you need a lot of spare headroom in the laser output and sensor sensitivity for them to play. Some models had lots of optical headroom and could thus play them even though they predated the invention of CD-R's, others without much headroom could not!

Different colour CD-R's had different reflectivity as well. If I remember right the silver backed "blue" CD-R's were more reflective than the Green/Gold type and were thus easier to play on old CD players, (our JVC could play the blue ones well but struggled with the green/gold ones...) but unfortunately the blue ones didn't seem to last as well - a lot of the blue CD-R's I burnt in the early 2000's are now flaking away at the edges so the song/data at the edge of the disc is lost...

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CitroJim
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Re: Citrojim's Skoda, Saxo, 207 and Bike Tales

Post by CitroJim »

No, the tracking, optics and all related are absolutely fine on this one Simon.. It reads the TOC perfectly and plays but there's no audio... Just a crackle at the start of playing a track (as the mute signal goes high) and on track changes...

All waveforms look normal but the reason for no audio is clear - the digital signal going into the DACs on both channels is static which will of course result in silence... You can se a little change to it at the start of play which is why you hear a little crackle! ... I'm currently tracing the signal path from the demodulator through to the error corrector and filter to see where it's all going wrong...

It's a voyage of great discovery as I'm having to learn exactly how these functions work... The structure of the data written on the CD is more complex than you might at first think...

I might even have to read the 'Red Book' to completely understand it all...

I will report back on how it goes....

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Re: Citrojim's Skoda, Saxo, 207 and Bike Tales

Post by Mandrake »

Ah - interesting. Never came across a problem like that. Nearly every faulty CD player I encountered had an issue with either the laser unit, or the servo tracking systems. Very unusual that it is able to track and "play" the disc but no audio data is being provided to the DAC... I will be most interested to hear the result. :)

Yes the data structure on the disc is interesting - EFM (eight to fourteen ?) modulation.... I'm assuming that the eye signal looks good and detailed, and the tracking servo signals and lens position are stable ? Does it seem to fast forward and rewind ok ?

Interesting comment about the mute signal as well - usually if there are sufficient read errors that the error recovery can't sort out it will trigger the mute signal to avoid blasting your speakers with nasty pops and clicks...

Does the mute line activate if you touch the edge of the disc to deliberately slow it down ? If you slow the disc just enough on a working player it should mute the audio.

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CitroJim
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Re: Citrojim's Skoda, Saxo, 207 and Bike Tales

Post by CitroJim »

The eye signal looks perfect Simon as does the HFD signal - the one that detects problems on the disc...

Manually slowing the disc does indeed elicit the expected response on the HFD signal and results in a mute...

The derived mute line that mutes down the audio also works entirely as it should...

Also, the next and previous functions work fine as does pause... All the timing signals look good and I can dee the demodulator PLL locking and the VCO working as expected...

I'm suspecting a problem with the Error Corrector and that's my next line of enquiry...

It certainly is an interesting one one but great for learning about how they work...

I will report soonest...

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Re: Citrojim's Skoda, Saxo, 207 and Bike Tales

Post by RichardW »

And I thought I was doing well replacing the belt for the disc load drive on ours.... :rofl2:

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CitroJim
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Re: Citrojim's Skoda, Saxo, 207 and Bike Tales

Post by CitroJim »

RichardW wrote:
13 Dec 2017, 23:23
And I thought I was doing well replacing the belt for the disc load drive on ours.... :rofl2:


Knowing how fiendishly complicated it can be to get inside some modern ones that's an achievement Richard; most modern stuff is not amenable to repair sadly..

Luckily, this 30+ year old player is... No more progress as I was too brain-dead yesterday after work. I only have about three hours a day when I'm blessed with reasonably clear thought and cognition; then the fog descends and remains...

Hopefully more progress today...

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Re: Citrojim's Skoda, Saxo, 207 and Bike Tales

Post by RichardW »

It took me rather a long time to figure out how to manually release the tray - there isn't any obvious latch, eventually solved by rotating the gear wheel, which firstly winds down the disc clamp, and then puts the tray out. not figured out how to get the tray back in with the drive in the correct alignment, but it can't be that hard can it!?! New belt was 63p from CSC - except that for orders <£5 there is a £2.50 handling charge :roll: and I'm not sure I've got the right one yet :lol: Ours is relatively modern TEAC Reference 300 - but realised it is now nearly 20 years old - we got it before we got married in 2000.... :shock:

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CitroJim
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Re: Citrojim's Skoda, Saxo, 207 and Bike Tales

Post by CitroJim »

If you manually would out the tray it'll realign itself automatically when it next powers up.. The mechanisms are quite rugged and designed to cope with all kinds of anomalies from jammed/stuck discs and power fails with the tray half-in or out...

Or manually wind it back in...

That's a nice looking CD Player Richard and well worth a bit of maintenance :)

Simon, I studied how EFM (Eight to Fourteen Modulation) encoding works... Very clever and in the case of a thing such a CD which can suffer all kinds of calamities that can corrupt the data it makes a lot of sense...

The brain is quite good today so more work on the CD player later today...

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CitroJim
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Re: Citrojim's Skoda, Saxo, 207 and Bike Tales

Post by CitroJim »

No work done on the CD Player today - or anything else for that matter...

The weather down here has been so lovely I went for a really gorgeous 32 mile bike ride :) It was cold and windy but beautifully sunny... Almost perfect for a good ride...

That completed an excellent triplet of physical training today :) Earlier I'd ran 5Km and then swam just over a mile (50 lengths of our pool)...

The only small downside was I picked up a puncture in my front tyre, maybe as a result of two instances of farmers butchering hedges today.

The tyre that punctured was old OE one from a previous bike of mine and not a fully puncture-proof one - only nominally puncture-resistant...

Luckily, the puncture was a relatively slow one and with two pump-ups I just made it home...

I had to wash the bike before I could properly fix it as it was filthy...

I fixed the puncture by replacing tyre and tube - no mucking around with patches for me - and fitting a nice new Conti 'Gatorskin' I'm not too keen on punctures and try to take all reasonable precautions to avoid them as far as is possible...

I did the job in my nice warm and cosy winter workshop :)
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And finally today, I walked up to the town and finished off my Christmas shopping :) All done!

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CitroJim
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Re: Citrojim's Skoda, Saxo, 207 and Bike Tales

Post by CitroJim »

It's been a fun morning :)

I ran our annual Santa Dash and thoroughly enjoyed it.. It's a fun run in support of our local hospice and it has to be run wearing a full Santa outfit :)

I ran to the event and back and gave a lot of people a great deal of pleasure and raised a lot of smiles amongst the good people of Newport Pagnell - I think the last thing they expected was to see a Santa out running on a wet Sunday Morning...

Many hundreds of Santas ran and here's just a few...
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I also adopted Suzy the Swan today in support of the hospice ;)

Here she is...
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And finally, I've entered a MK to Amsterdam and back bike ride today. It will take place in late June and is again a fund raising event for the same hospice..

I was looking for a big cycling challenge in 2018 and now I've found it :) can't wait to get cracking on it...

https://www.willen-hospice.org.uk/get-i ... -challenge

Anyone fancy joining me and making a gentle, social holiday-type return journey through Belgium and France?

I should add that I do a lot of fund-raising for this hospice and have for a long while... It's our local one and they do a sterling job of caring for those who sadly have reached the end of their lives for whatever reason... I'm staggered that all of their running costs comes from fund-raising; they get no help from government at all and they need to raise something approaching a tenner per minute every day of the year just to keep going...

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bobins
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Re: Citrojim's Skoda, Saxo, 207 and Bike Tales

Post by bobins »

CitroJim wrote:
17 Dec 2017, 15:38

And finally, I've entered a MK to Amsterdam and back bike ride today. It will take place in late June and is again a fund raising event for the same hospice..

I was looking for a big cycling challenge in 2018 and now I've found it :) can't wait to get cracking on it...



You'll be needing one of these to cross the water then :lol:
Floating bike - BBC fair use
Floating bike - BBC fair use
floating bike.jpg (34.24 KiB) Viewed 53 times

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Re: Citrojim's Skoda, Saxo, 207 and Bike Tales

Post by Hell Razor5543 »

When I was in Lymington last Sunday there was a Santa dash planned. I saw more Santas' then people in normal clothing. If I ever decide to take part in such a run I might go dressed as a demon. When people complain I will say "I am dyslexic, and I thought it was a Satan run!". :D