Babbar
Member
Last Activity: 11-16-2024, 05:12 PM
Joined: 11-25-2023
Location: Stockholm
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Checked these for open and short circuit, they passed those tests at least but didn't do a proper job checking the ratings. If you think them being bad might explain the symptoms I'll take the machine apart again and have a proper look/measure!... -
Exactly, with maximum i mean the speed control turned all the way. The trigger switch is just on/off so speed control is implemented via the pot etc. Attaching some more pics, one of the board traces. I didn't do a very good job checking the other resistors, just confirmed that they were not open or short which they were not. If the "thermistor" is actually something else and behaving as intended then I don't know what to focus on, might just try to buy replacements for all the components but would be nice to narrow it down a little bit....
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Yep, it is supposed to be a 220k pot and i measured it going between around 12 Ohm and 114 kOhm so should be good.
Just using the symptoms of the machine i.e. it works fine on maximum speed setting but not at all otherwise. Does that point to a capacitor issue most likely or could it as well be the triac not working correctly?...Leave a comment:
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1980s Holz Her 2420 belt sander - Only works when speed control at maximum
My fathers belt sander from the 80s which i very much would like to continue using has an issue with the speed control. The machine works fine on maximum speed but will not turn or give any sign of life when on any other setting. The speed control is a dial going from 1-6 although implemented as a potentiometer without distinct steps. I took the machine apart and measured each component individually, all components and measurements have been captioned in the attached pictures. The Triac did not get identified correctly using my cheapo component tester, i don't know if this is user error, if the...
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Taken the amp apart again and looking at the power supply board but not getting anywhere =). At the moment feeling like i'm out of my depth with this repair as i don't know what to expect. It's confusing that the device seems to work fully; powering on and allowing bluetooth connection etc but at the same time i get the feeling that the PSU has some major issues.
Having the PSU plugged in but disconnected from the main board, what should i expect from the various connectors on the power board? If it says on the MB +12V and G on a connector which leads from the PSU, should i expect...Leave a comment:
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Parts arrived today, put in the new rectifier and power MOSFETs and nothing blew up, the lights come on and i can connect my phone via Bluetooth. So far, so great =). But... there is no sound. I've tried two different BT sources and connected via line-in. Also tried two different speakers. All seems to work without issue but without any sound coming to the speakers. Have no idea how to continue at the moment, any ideas welcome! Also, what do you think, should i focus my energy on the PSU or the motherboard at this time? From what i can tell using my IR camera there is nothing getting hot on the...
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Ok cool, will remember that if/when i come across it! Going to order the parts now, should show up in a couple of days so then the fun continues =)....Leave a comment:
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Ok, just checked and AC line and neutral still have good connections to the AC inputs of the rectifier....Leave a comment:
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The rectifier doesn't look blown in any way that i can see but when i use my multimeter it measures dead short on both +\~ and -/~ so i'm thinking it is gone for sure. My main fuse did blow when i plugged in the amplifier, wrote that in my initial message that both the device fuse and wall fuse blew.
I appreciate all your help on this little project which hopefully leads somewhere, if nothing else some new knowledge!...Leave a comment:
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Followed the gate of the MOSFETs back through some resistors and diodes to an ST L6599A IC which is a high-voltage resonant controller according to the spec i found. Don't know how to check it fully for faults but at least didn't find any shorts on the way to it or on the connecting pin (nr 15 HVG). Planning to order replacements for the MOSFETs and bridge rectifier this evening and hope to get the amp running again without more bangs =)....Leave a comment:
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You live you learn =P. Thanks for the clear info on do's and don'ts of replacing MOSFETs! Would it have been a better idea or maybe even good idea if i had replaced the two broken ones with two matched K10A60D or two K12A50D? Or should you always aim for an exact replacement with original?
How do you check the gate drive circuit state? Will it always blow if it is stuck in the on state?...Leave a comment:
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Good suggestion! I checked the rectifier and it is indeed borked as well. Measures open on both +/~ and -/~. Need to source a replacement now, model GBU606 (6 A 600 V)....Leave a comment:
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Argon SA1 audio amplifier power-supply - fuse blown after fixing the short?
I found a project in the electronics trash yesterday. A nice Argon SA1 audio amp with some electrical issue. Took it apart and saw that the 4A250V fuse was blown so started lifting components to find the short. Eventually got to two MOSFETs (model FTA14N50C) that are shorted and when i took them out the short was gone.
Now i didn't have any replacements of the same model of course but i found a couple with pretty similar spec i thought (K10A60D & K12A50D) and put them in. Also replaced the blown fuse with a 3.5A250V one. Checked another time for short circuit and plugged it in.... -
And the results are in! Both X2 yellow film caps were borked on both boards. I had some replacement 224 (220 nF) ones from scraps but will need to wait for the 334 (330 nF) replacements.
Many thanks again [USER="15329"]stj[/USER] and [USER="29541"]redwire[/USER] for the tips!stj...Leave a comment:
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Much appreciated! I will have a look ASAP =)...Leave a comment:
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Electrolux Ultrasilencer and UltraOne vacuum cleaners not starting
Hi all!
New to the forums, this is my first time posting so hoping to do a good enough job making sense.
I have two vacuum cleaners having the same issue of not being able to start on their own but when they get going (by manually shorting power to the motor on the internal PCB) they will keep running and also allow me to switch on and off again for a while using the power switch until the issue returns.
The models are below and i will attempt to attach pictures of both sides of the PCB from one of the machines (they look basically identical).
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Hej från Stockholm!Leave a comment:
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