Thanks all for the kind words.
The amp was a repair but owner decided to offload it. Speakers, reverb tank,
OP tubes replaced + electronic tweaking as previously noted. Due to the poor
cosmetic condition I decided to do a complete refurb to increase odds of selling.
A studio owner client asked to try it in a session and it never left there.
I guess that's job done. 🙂
TCD
Today I had two hypex plate amps on the bench that are part of some ADAM monitors. The customer complained about different sound between both. As the "reference" was unknown I had to investigate both. Measuring supply voltage the pos op-amp rail showed -0.7V instead of +15V. This is a strong indication of 7815 latchup I experienced with ST 78M15 and 78L15. Indeed I found ST 78M15 on these boards. Adding a Schottky diode antiparallel to the output did the trick. But the function test still showed big differences between both. Tracing the audio signal path the pre-amp section seemed to be ok from input jack to the coupling caps of the UcD-power stages. Behind the coupling cap signal dropped significantly. So I removed these black sleeved 22uF/50V caps and measured them. Not a single one showed more than 5nF, these caps were as dry as the Sahara. After replacing 2x2 coupling caps on both modules things looked fixed. Having another look on the modules I discovered more of these infamous caps in the power area between the heat-couplers. Desoldered them all - and all these black 22u/50V were dead! The blue 100uF/16V showed about 70% of their capacitance - not too bad in a module aged 16 yrs. As the bigger caps did not show problems I replaced all these thin caps by new 105C variants and everything is fine now. Drying out over the years seems to be a matter specially of thin electrolytics exposed to higher ambient temperatures. Considering these caps and the al-cheapo trimpots made from Piher my impression is that the penny pinchers at hypex did a decent job.
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B&D Workmate.
Background - got it when married & first house 30+ years ago. Abused it & it was well knackered but kept it thinking I might fix it up.
Meantime bought a couple of the cheap folding workbenches which I disliked. Jaws tilt under clamping pressure. Unstable unless you can keep your foot on the frame. Geometry wrong so they don't fold flat.
Finally decided enough was enough & sourced the parts. Full spares pack ordered. 24mm Birch ply piece ordered big enough to do the job (full sheets are very expensive!).
An evenings drilling & cutting including routering the groove along the jaws and hard waxing. A quick spray of black gloss over the frame (it had paint overspray from using it as a painting bench, another couple of hours fitting the new leg clips, vice handles, reassembly & new feet. Now better than new since originally it had particle board jaws. Also, the rear jaw is now 50mm deeper - if I don't like it I can cut back to standard. Just need to glue the feet on because I remember them always falling off.
Background - got it when married & first house 30+ years ago. Abused it & it was well knackered but kept it thinking I might fix it up.
Meantime bought a couple of the cheap folding workbenches which I disliked. Jaws tilt under clamping pressure. Unstable unless you can keep your foot on the frame. Geometry wrong so they don't fold flat.
Finally decided enough was enough & sourced the parts. Full spares pack ordered. 24mm Birch ply piece ordered big enough to do the job (full sheets are very expensive!).
An evenings drilling & cutting including routering the groove along the jaws and hard waxing. A quick spray of black gloss over the frame (it had paint overspray from using it as a painting bench, another couple of hours fitting the new leg clips, vice handles, reassembly & new feet. Now better than new since originally it had particle board jaws. Also, the rear jaw is now 50mm deeper - if I don't like it I can cut back to standard. Just need to glue the feet on because I remember them always falling off.
Wowza. Impressive! 🙂
Coincidentally, the longest distance I've ever cycled in one day was 37 miles ...just reverse the order of the two digits in your ride to get my longest. And that was many years ago, when I was much fitter than I am now.
-Gnobuddy
just asking any other full-time professional techs on here?... we are normally a bit quieter this time of year, but now with Covid-19 restrictions easing I am getting up to 15 jobs a day just for audio work come in...its gone absolutely crazy...is it because they cant afford new things or are they are bored at home?
And yes I cant keep up lol
And yes I cant keep up lol
73 miles is just plain awesome.
I think I managed to get in a 52-miler once around seven years ago. Like you, I was much fitter then. But hope springs eternal; I'm currently embarking on a "disemporkulation" regime, mainly through improved diet and running.
And to stay on topic, I was able to fix my Garmin watch today. It croaked mysteriously after this morning's run, but I was able to revive it through a mysterious combination of "button jive".
I think I managed to get in a 52-miler once around seven years ago. Like you, I was much fitter then. But hope springs eternal; I'm currently embarking on a "disemporkulation" regime, mainly through improved diet and running.
And to stay on topic, I was able to fix my Garmin watch today. It croaked mysteriously after this morning's run, but I was able to revive it through a mysterious combination of "button jive".
not repairing anything at the moment after breaking my arm.
left hand typing is very slow.
very frustrating as i have 3 new pcb's for new projects and cant get started.
left hand typing is very slow.
very frustrating as i have 3 new pcb's for new projects and cant get started.
Hi deadpool,
Yes. I'm a professional tech and I'm turning away work because I can't keep up. Then there are the industrial jobs ...
-Chris
Yes. I'm a professional tech and I'm turning away work because I can't keep up. Then there are the industrial jobs ...
-Chris
> What did you last repair??
Seized brake caliper on 1996 Honda Odyssey minivan (really an Accord built tall).
Never get many years out of these.
What galls me is the Core Charge is up to $83!! For maybe $20 of steel castings. OK, there's a large precision bore (which they should re-hone) and some hardwares.
This iron core costs more than beef.
Seized brake caliper on 1996 Honda Odyssey minivan (really an Accord built tall).
Never get many years out of these.
What galls me is the Core Charge is up to $83!! For maybe $20 of steel castings. OK, there's a large precision bore (which they should re-hone) and some hardwares.
This iron core costs more than beef.
The son of one of my friends is a guitar tech, and a very good one. He lives in the USA, the country worst hit by COVID-19, so so he's had a very, very rough time financially. But apparently there's recently been a complete U-turn, and now he's getting so much work that he's got some 19 guitars backed up, waiting their turn.
Keep in mind, this guy is so good he gets the challenging and time-consuming jobs - like complete re-frets on very valuable vintage Gibsons. We're not talking ten-minute string changes here. 🙂
Why the sudden rush of work? My guess is that more people are turning to their music for personal fulfillment in these dark times. If true, it's a small silver lining to this very large cloud we're all living under.
-Gnobuddy
Me too although I'm semi retired these days, work part time as a tech in a Hospital. Been quiet for us as the hospital was not doing elective surgery.
I'm surprised people are getting audio gear repaired as we are a throw away society today. BTW I did my apprenticeship with Marantz.
The last think I repaired, or better, modified, is a personal ultrasound physiotherapy unit. There was a bad connection which made the equipment work incorrectly and intermittently.
In the modification, I moved the PCB from inside the hand held ultrasound applicator to a separate box. This was contrapted out of a 6"x3" wall socket box and a 1mm aluminium sheet to cover the top. The PCB was bolted to the aluminium sheet using hard insulating washers as a spacer. The output NPN NEC D882 transistor was moved from the PCB to a small heatsink that was bolted to the aluminium sheet for better heat transfer and convenience. Three push to make switches where mounted on the aluminium sheet to turn on/off the device, another to increase the ultrasound intensity and another to decrease it. The power connector was removed and wires were soldered instead.
Needless to state, the contraption works better than the original.
Doing some research reading about how medical ultrasound piezo sources are driven, I found they are connected to oscillate freely after being excited by a powerful pulse. The driver delivers these pulses at a much lower frequency than the piezo's free frequency.
In the modification, I moved the PCB from inside the hand held ultrasound applicator to a separate box. This was contrapted out of a 6"x3" wall socket box and a 1mm aluminium sheet to cover the top. The PCB was bolted to the aluminium sheet using hard insulating washers as a spacer. The output NPN NEC D882 transistor was moved from the PCB to a small heatsink that was bolted to the aluminium sheet for better heat transfer and convenience. Three push to make switches where mounted on the aluminium sheet to turn on/off the device, another to increase the ultrasound intensity and another to decrease it. The power connector was removed and wires were soldered instead.
Needless to state, the contraption works better than the original.
Doing some research reading about how medical ultrasound piezo sources are driven, I found they are connected to oscillate freely after being excited by a powerful pulse. The driver delivers these pulses at a much lower frequency than the piezo's free frequency.
Ceiling fan.
Came with the house. Too large for the hall so someone trimmed the blades. It has always wobbled.
Last week it started a mild banging. Shopped for a new fan. Then got less-dumb and played with the fan. Yup, one of the 2 box-screws was coming loose.
I thought maybe it unscrewed from the shake but it now seems the hole is nearly-stripped. There's another next to it and that also strips! Plastic box, not a surprise, but this is an old beefy one and they were hard to strip. I wonder if the screw is buggered enough to be tearing the threads out.
Of course a decades-old fan is a dust-disaster. Yuck.
After washing the blades I put them on the postage scale. Two were 0.415lb and two were 0.410lb. 2 or 3 grams difference. I hadn't kept them straight coming down, but when I put them up in matched pairs the first-order wobble is much less. There's a high-order shimmy which may be air-forces, but teeny.
I would not object to $40-$99 for a new fan. But the mounts have changed and really it should be a fan-approved box. So a replacement becomes too much work on top a ladder at the top of the stairs, in the dark. Nah, big screw, sort blades, let it go another decade.
Came with the house. Too large for the hall so someone trimmed the blades. It has always wobbled.
Last week it started a mild banging. Shopped for a new fan. Then got less-dumb and played with the fan. Yup, one of the 2 box-screws was coming loose.
I thought maybe it unscrewed from the shake but it now seems the hole is nearly-stripped. There's another next to it and that also strips! Plastic box, not a surprise, but this is an old beefy one and they were hard to strip. I wonder if the screw is buggered enough to be tearing the threads out.
Of course a decades-old fan is a dust-disaster. Yuck.
After washing the blades I put them on the postage scale. Two were 0.415lb and two were 0.410lb. 2 or 3 grams difference. I hadn't kept them straight coming down, but when I put them up in matched pairs the first-order wobble is much less. There's a high-order shimmy which may be air-forces, but teeny.
I would not object to $40-$99 for a new fan. But the mounts have changed and really it should be a fan-approved box. So a replacement becomes too much work on top a ladder at the top of the stairs, in the dark. Nah, big screw, sort blades, let it go another decade.