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What is on your workbench right now?
Mount it on the wall for nostalgic memories.
A recently-acquired VTL ST-125. Previous owner gave up after the amp would chew through 807 output tubes. I traced the circuit out and was surprised/disturbed to find that this amp applies over 500V to the 807 screens (max rating is 300V). So first step, I'm putting in regulators for the screens to hold them at 300V. If that works, I'll probably end up pulling out the main board, replacing it with perf metal and terminal strips (much better thermal management), and convert the outputs to "super" 6BG6 (really, rebased 6L6GC/7027), input stage to something better than their modified Mullard 5-20 circuit, and drive the outputs into AB2.
Not a great start to my 2024 as I tested this meter more and found it was not very accurate.
The battery corrosion had migrated to the underside of the switch PCB. I hit with contact cleaner and cleaned up pretty well but the negative 1.5v connection to the board broke off and tried to resolder. This strained some other brittle wiring and lost 2 more connections so decided it was no longer worth my time. Packed it up and is headed for the multimeter grave yard.
Oh, no, I am very sorry and sad to read your post.
Even though my multimeter (ref. my above post #556) still works perfectly fine, your story urged me to check and change the battery...
Our workhorse business printer is a Canon MF229dw.
The printer has been a champ except for the ADF hinges. I replaced them once previously but this past week they appeared to fail again. I ordered replacements but after taking apart the printer (a major wiring exercise but helpful youtube videos are posted), found the springs intact but the ADF’s mating plastics were badly broken.
These powerful hinges hold open the lid when replacing the toner cartridge. Without any good way to repair the plastic enough to deal with the force of the spring-loaded hinge, was ready to buy a new printer. Then remembered how the old hinges failed -the bottom broke off and the spring pops out. Figured I could use the hinges without the spring loading. So got out my dremel with a cutting wheel and carefully cut off the bottom of the hinge. As was already wearing eye protection, just needed to be prepared for the spring to eject! If you are careful, can score the plastic and the spring does the rest of the job.
Once I had 2 modified hinges was able to remount them in the base and use some epoxy to attach them to the bottom of the ADF. Rewired and buttoned up, the printer is back in business and avoids landing in the recycle bin for now!
The printer has been a champ except for the ADF hinges. I replaced them once previously but this past week they appeared to fail again. I ordered replacements but after taking apart the printer (a major wiring exercise but helpful youtube videos are posted), found the springs intact but the ADF’s mating plastics were badly broken.
These powerful hinges hold open the lid when replacing the toner cartridge. Without any good way to repair the plastic enough to deal with the force of the spring-loaded hinge, was ready to buy a new printer. Then remembered how the old hinges failed -the bottom broke off and the spring pops out. Figured I could use the hinges without the spring loading. So got out my dremel with a cutting wheel and carefully cut off the bottom of the hinge. As was already wearing eye protection, just needed to be prepared for the spring to eject! If you are careful, can score the plastic and the spring does the rest of the job.
Once I had 2 modified hinges was able to remount them in the base and use some epoxy to attach them to the bottom of the ADF. Rewired and buttoned up, the printer is back in business and avoids landing in the recycle bin for now!
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DonR
Major Contributor
Been sitting on my shelf for over a year, time to fix this Keithley 485 Picoammeter
Best of luck, hope it's a mechanical switching issue or like.
The psb and all the surface chips scares the hell out of me.
DonR
Major Contributor
Its an issue with the A/D converter which itself is mostly discrete and generic 74HC logic. The scary part are the precision parts in red at the bottom under the ribbon cable. Teflon standoffs always scream DO NOT TOUCH to meBest of luck, hope it's a mechanical switching issue or like.
The psb and all the surface chips scares the hell out of me.
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Haflermichi
Active Member
Sony CDR-W33, Audio only CD-R recorder. This is my second unit. Listed on eBay as "drawer won't open".
Drawer belts on these stretch and/or break over time. Having done this job before and having a spare belt on-hand, I got it.
It turns out to have a completely different drive than my first unit. It was completely enclosed which necessitates practically disassembling
half the chassis to get to removal screws.
But I got in. The belt had melted into goop. Replaced the belt and all back together now.
I use them to burn vinyl.
Always loved the industrial look of these machines.
Drawer belts on these stretch and/or break over time. Having done this job before and having a spare belt on-hand, I got it.
It turns out to have a completely different drive than my first unit. It was completely enclosed which necessitates practically disassembling
half the chassis to get to removal screws.
But I got in. The belt had melted into goop. Replaced the belt and all back together now.
I use them to burn vinyl.
Always loved the industrial look of these machines.
bothu
Member
Around these teflon stands there are a lot of dust on the pc board.
Can the dust act as a a conductor for current leakage ?
Bo Thunér from Sweden
DonR
Major Contributor
That would definitely be a problem but it had this fault a year ago before it started collecting dust (and I foolishly left the cover off). Also, the fact that it uses Teflon standoffs means that the PCB underneath is not terribly critical. The issue is that it displays the same current on every range even when there is no input or the input is shorted which says ADC to me, maybe I'm wrong. The front end and amplification stage check out fine and the MCU/display seems to work fine too.
I have been using YOKOGAWA CL220 Clamp-On Tester (AC/DC Current Meter) for about 20 years mainly for checking power consumption of my audio and other electric gears as well as total house AC power consumption; it is really accurate and robust. Do you, my ASR friends here on this thread, use a similar one?
I can used it also for checking/testing the rough total house leakage current (resolution is 10 mA), and if needed to identify the current-leaking (to ground) device(s)/home-appliances.
I can used it also for checking/testing the rough total house leakage current (resolution is 10 mA), and if needed to identify the current-leaking (to ground) device(s)/home-appliances.
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Bamboszek
Active Member
- Joined
- Mar 17, 2018
- Messages
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Not exactly same, but in my previous job I used tons of Yokogawa current probes. Sometimes even 6 probes with multichannel scope for one measurement.
701918 Current Probe 120 MHz / 5 ARMS
701933 Current Probe 50 MHz / 30 ARMS
701930 Current Probe 10 MHz / 150 ARMS
701931 Current Probe 2 MHz / 500 ARMS
They were really handy as they are able to measure DC to even 120 MHz current waveforms - unlike Rogowski coil which struggles with DC and LF AC.
Resolution and noise was surprisingly good too, especially when a few turns were used to increase sensitivity.
701918 Current Probe 120 MHz / 5 ARMS
701933 Current Probe 50 MHz / 30 ARMS
701930 Current Probe 10 MHz / 150 ARMS
701931 Current Probe 2 MHz / 500 ARMS
They were really handy as they are able to measure DC to even 120 MHz current waveforms - unlike Rogowski coil which struggles with DC and LF AC.
Resolution and noise was surprisingly good too, especially when a few turns were used to increase sensitivity.
bothu
Member
- Joined
- Jul 21, 2019
- Messages
- 2,583
- Likes
- 3,808
I found this Hafler DH101 preamplifier recently in a thrift store, and small wonder no one else had snagged it before me: The top cover was badly rusted, paint was flaking off, and overall, it seemed neglected. But the insides looked like 1970s/80s factory stock. Am thinking I'd like to replace all of the original resistors and capacitors, and while I'm at it, I might as well replace the RCA jacks with a drop-in replacement offered by Akitika, because the originals are in poor condition.
Pye Type P 'portable' radio from 1932.
Uses 4 different HT voltages, 2 different grid bias voltages and 2v heaters. The batteries must have been interesting. Also has a loudspeaker of 12,000 ohms impedance! No output transformer.
Somebody cut a lot of the wires internally, and together with the powering difficulties, I may not be able to do a lot, but lovely to get my hands on something 90 years old!
S.
Sometimes, when I get nervous, I take things apart...
This is a Logitech G604 mouse. The left button occasionally does a double click when only a single click is requested. Scuttlebutt on the internet suggests that an air duster might fix it. I've tried this externally, and I think it reduced the issue, but it's not completely resolved, hence the disassembly. The white 'sergeant stripes' are the replacement PTFE feet, which took around 5 days to arrive from China
Done! I tested for double clicks on a couple of on-line tools and got zero back, the 'new boots' look nice as well
This is a Logitech G604 mouse. The left button occasionally does a double click when only a single click is requested. Scuttlebutt on the internet suggests that an air duster might fix it. I've tried this externally, and I think it reduced the issue, but it's not completely resolved, hence the disassembly. The white 'sergeant stripes' are the replacement PTFE feet, which took around 5 days to arrive from China
Done! I tested for double clicks on a couple of on-line tools and got zero back, the 'new boots' look nice as well
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restorer-john
Grand Contributor
I'm more interested in the Yamaha CR-1000 on the shelf....
LoL.... hehe.
I'm interested in the HP distortion analyzer. I had one at my bench to satisfy service agreements but never used it once. Is it difficult to operate? I heard they are a bitschy thing at times.
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