CitroJim's AX, C3 Picasso, Cycling and Running Tales

[CitroJim]

I have recently taken up watch repair as a hobby, and have bought the tools required for basic watch overhaul.

Excellent

That's not so far removed from my camera repair side-hustle Mike Those two activities have a lot in common...

No progress on my grandfather clock these past two days due to intense activity on legal side in connection with a house purchase.

The new catgut has arrived so hopefully I can progress with the job this weekend although youngest is home for the weekend so it may not happen. I want to spend time with her...

The hoops I'm having to go through to prove I'm financially legit and not some shady drug dealer and money launderer is almost beyond belief...

They want to know, as my dad used to wryly observe, 'the in and outs of a cat's arse...'

I knew it was a bad idea to have a 'burner phone'... It's now come back to bite me on the bum

New granddaughter is thriving - not far off being a whole week old now

[xantia_v6]

This looks as though it is right up your street Jim.

I'll never know Steve, the video is broken

On the page that says its broken, there is a link to watch it on youtube, which seems to work. Quite a nice Japanese watch. I have a practice watch which is a downmarket japanese brand with too many plastic parts inside.

[myglaren]

This looks as though it is right up your street Jim.

I'll never know Steve, the video is broken

It is just prevented from embedding but if you click the "Watch On YouTube" ink it opens n another tab.

So many small parts!

[CitroJim]

This looks as though it is right up your street Jim.

I'll never know Steve, the video is broken

It is just prevented from embedding but if you click the "Watch On YouTube" ink it opens n another tab.

So many small parts!

Ahh, that's better!

I can do cameras and clocks without it although to do watch repairs I'd need some serious magnification! Although, to be honest, a bit of magnification when working on cameras would be useful at times...

I made good progress with the grandfather clock yesterday after parkrun. I've cleaned and degreased all parts of the movement and it's now 90% reassembled.

It should be ticking again later today

Speaking of parkrun, following a commencement of light physio on Friday, I was happy to see distinct improvements in my walking although I only walked a total of only about a mile in three sessions. I also successfully drove to the station to meet Sian, my younger daughter She then took over driving as that was enough for one day

I'll be spending time with her today which may impact on clock progress...

Forgot to say, on Friday I had my first shower in three weeks. It was bliss. That and sliding into freshly laundered bedding

I'm due another shower this evening. Can't wait! This is allowed now I've been trained in how to properly dress the operation site...

Or as it has been christened: 'The Shark Bite'...

[RichardW]

Good to hear you on the mend! Hopefully not lost too much muscles resulting in a lopsided run now

[CitroJim]

Good to hear you on the mend! Hopefully not lost too much muscles resulting in a lopsided run now

Thanks Richard

After a shower and re-dressing the shark bite I'm noting some good healing progress now. It's still looking a bit gruesome but not quite as much as it was!

And the clock is ticking again

Life is slowly returning to normal and to underline that, I'm going to Tesco in a bit for my weekly shopping. I've been relying on on-line shopping for a few weeks. It's OK when circumstances dictate but in no way does it beat going shopping in person.

Then I'm going for a short ramble with my running club

[CitroJim]

A good start at slowly getting back to normal yesterday

It was a very brisk walk and very good physio as well as being very social. We all met up in the café afterwards

One of the events my running club holds a coupe of times a week for those who are injured or otherwise cannot run...

I'm still a way from running as yet... Getting there though

[CitroJim]

Now the grandfather clock is now all good and much else that had been patiently waiting for me to recover a bit has now been dealt with, I could finally turn my attention to your amp. Bobins

Nothing obviously out of order found so far. The resistors that are cooking are in the headphone socket circuit. Why, I've not yet determined. Could be a large DC offset on the speaker lines. Did it by any chance kill a set of speakers when it last blew up Bobins?

I'll be dummy-loading it when I first fire it up after more checks.

The amp. has a great reputation and go for eye-watering amounts on eBay But, my goodness, the build quality is worse than a 90s British Leyland The PCB is very fragile and the whole shebang is not well designed or put together at all. Not surprising the company went bust and the original designer - who's well-known on some audio forums - denies all knowledge!

And, I'm having to do a lot of reverse engineering as there's no circuit diagrams to be found anywhere...

A good challenge. It may be a while but it'll play again

Before that, I enjoyed another very good long, brisk walk in the interests of my ongoing physio and in general I'm feeling really quite well and happy. Some difference from a couple of weeks ago

It's almost a month since the surgery and I'm hoping today will be my last visit, for a while at least, to Stoke Mandeville.

Just before the amp. occupied the bench, I replaced a broken film door latch on one of my Canon cameras... Quite a lot of disassembly needed although straightforward.

What amazed me was just how quickly the spare part arrived from China. I ordered it on eBay only a few days ago. Stuff from China seems to arrive quicker and with much less aggro than from mainland Europe. Postage was free too. Bizarre....

The part is not genuine and doubtless is just 3D printed but it does the job and cost less then a tenner. Result

[bobins]

I knew the amp. had issues, Jim, but I didn't know it was that bad inside
It never blew the speakers it was attached to (late 90s B&W P6), but I do remember it cutting one or both channels - sometimes a bit of percussive maintenance on the case would bring them back, sometimes flicking the mute (?) button on and off would work. Eventually nothing would work. I went over the circuit board with a magnifying glass looking for obvious dry joints or broken legs but couldn't find anything. Not a problem if it proves unfixable or just too much of a PITA as I'm several amplifiers down the line since that one !
Thanks for taking it on though

[CitroJim]

I've done some more work on it Bobins, and I find the left channel is OK but the right channel has a DC offset of some 40V on the speaker output. Both output transistors are rammed hard on! The fuses would have popped to protect the speakers... No wonder that resistor was unhappy!

Time was limited yesterday as I was both at hospital and spending time with family. I've now been discharged from hospital care and can now start to get back to some normality - gently and in easy stages! I'm now permitted to run and cycle short distances

I started that off well by spending a lot of time yesterday afternoon chasing Autumn around a big play park

Today I'll be making the most of my new-found freedom and will celebrate with a short, easy run and bike ride... A sort of slow duathlon

Then it'll be back to the poorly amp. One of the benefits of the late afternoons and evenings being so dark now - it gives me more time to work in my workshops...

Yesterday late afternoon I used the time profitably to develop the film full of photos I took of both my granddaughters yesterday

[bobins]

Ah, I see

Not being electrically minded, and in words of one syllable or less so I can understand, what would cause those transistors to be on ?

[xantia_v6]

Back in my youth I did contract repairs of amplifiers for a local hi fi shop, once a week they would drop off half a dozen dead amps and the following week they would pick them up. Blown output transistors were common, often for no apparent reason. Some came back several times, I usually suspected mismatched speaker impedance, or parasitic supersonic oscillation of the amplifier. My general feeling was that audio amplifiers of that era had pretty marginal design and were just waiting for an excuse to blow the output transistors.

[bobins]

........or parasitic supersonic oscillation of the amplifier.

Is that the electronics version of the phrase used to confuse the apprentice ? Similar to the engineering version of 'a bucketful of sparks for the grinder' or the painter's 'pot of stripey paint' ?

It sounds like the sort of thing Dr Who would come up with to explain why the TARDIS is malfunctioning

[CitroJim]

My general feeling was that audio amplifiers of that era had pretty marginal design and were just waiting for an excuse to blow the output transistors.

Yep, that sums it up very nicely Mike and with everything DC-coupled it's ripe for an avalanche.

This amp., and I'm sorry about saying this Bobbins, falls into the category of 'fur coat and no knickers' Looking at the underside of the circuit board it would appear they employed Stevie Wonder to do the soldering and he misplaced the decent stuff and used plumbers solder and flux instead.

I'm going to look out for parasitic oscillations as it's a well-known killer of many amps. A dead giveaway is very hot output transistors with no input...

As I say, it will work again

I had no opportunity to do any work on it yesterday as I was too busy running, cycling and assorted domestic jobs - now that I can I'm still busy trying to catch up on all that had to be neglected for a month. Today the garden calls...

I did do one little job and that was to give Bluebell's battery a conditioning charge. I can't yet get into her to get her out of the garage even if I wanted to MoT her. Besides, before that I want to revisit her slightly intermittent starter problem.

It'll be good to get the spanners out...

[bobins]

The back of the board may look like an explosion in a smelting factory, but the sound that came out of the speakers more than made up for that in my view