dkneyle
Badcaps Veteran
Last Activity: 04-07-2024, 07:35 PM
Joined: 12-16-2013
Location: Tathra, New South Wales
-
Dagav, if your LED tester says the panel LEDs are busted, then what is the point of going further? Those testers are pretty good at firing the LED string if there's nothing wrong with them. From what you have described, I'd certainly also suspect a failed mainboard if you aren't getting any turn backlight on voltage signal. I assume you have +5v standby supply?... -
Re: GP0812LD SMPS IC possible substitute?
My man, Larry, ran the local electronics repair shop until it became uneconomical to do so any longer. So he recently joined our team and we are the only service available to people to get their stuff repaired.
Larry knows repairs better than me because he's had more recent practise doing so. But as you well know, when a SMPS has stopped it can be difficult to track down why because of the feedback circuit. But I'll pass all this onto Larry and let you know how we go.
Cheers, DLeave a comment:
-
Re: GP0812LD SMPS IC possible substitute?
Hi RJ,
The SMPS is in at the Repair Cafe - a volunteer organisation that only operates on Fridays. (And actually, we are closed this coming Friday- so it will be the following Friday before we get back to it again.)
My plan was to photograph it and get those images through to you.
Obviously a datasheet would be helpful if we knew what the IC really is?
I'm also going to get my colleague who is doing the actual work to look and see if it might be a bad cap? Usually, if the controller...Leave a comment:
-
Re: GP0812LD SMPS IC possible substitute?
I reckon you are right about it being an in-house ic number. I too could only find a Chinese site where someone was also trying to identify it.
Can't tell output voltage as non functioning.
Will get those images through to you,Leave a comment:
-
GP0812LD SMPS IC possible substitute?
We are fixing a panel heater with a SMPS, and the switching IC appears to have failed. 8-pin DIP. Type GP0812LD with a manufacturing logo that means nothing to me.
Can't find anything on the net about it. Does anyone here have any knowledge of it?? -
Re: MK1210 chip SMPS based supply - can I fire this up?
Well, disregard most of what I said in Post #18. After quite a few hours of heat soaking the problem returned. Some careful application of heat from a hairdryer and cooling with freezing spray would seem to indicate R33 (which coincidentally in 33 ohms) is the culprit. It actually reads as 27.5 ohms, which is outside the expected 5% tolerance. When I can get my hands on a proper high wattage resistor I'll change it out and confirm if it the source of the problem. Interestingly, it is connected to D23, which was the original...Leave a comment:
-
Re: MK1210 chip SMPS based supply - can I fire this up?
The Onkyo laser player bounced. Loss of audio after about 15 minutes. I think I’ve repaired that, and I’ll detail it here, because it might help others fixing these with similar issue.
It was obviously a heat sensitive issue. When I ran without the cover, I couldn’t get it to fail. Using a hairdryer as a heat source applied to various sections I was able to track it back to the power supply. Using freezer spray seemed to indicate it was in the vicinity of the 4 motor drive power transistors, although...Leave a comment:
-
Re: MK1210 chip SMPS based supply - can I fire this up?
I’ve continued to watch YouTube videos where VFDs have failed in different types of HiFi gear. They always seem to use a very similar circuit, and referring to the VFD Manufacturer recommended circuit it appears they have all adopted it.
There is an electrolytic cap connected to ground after the resistor in question. If it develops poor ESR then excess current flows through the resistor and it fails. Nearly always the solution in every case I’ve watched is this resistor with a value of about 50 ohms....Leave a comment:
-
Re: MK1210 chip SMPS based supply - can I fire this up?
Yep, all other components downstream were checked. As a matter of course I changed out all the electro caps on the secondary and primary side (except main charge caps) to ensure longevity and upped the voltage where that meant the cap could still physically fit.
I sometimes wonder about designers of circuits? Do they just go looking through catalogues and find some exotic component and decide "I'll give that a go". You confirmed what I thought: most fast recovery diodes should do the job. This designer has used...Leave a comment:
-
Re: MK1210 chip SMPS based supply - can I fire this up?
Well, I should have listened to Momaka's advice a bit more closely about VFDs.
A VERY expensive lesson learned, after importing a replacement front panel at extraordinary shipping cost from USA and currency conversion. There was no change with the replacement panel so I had to go back to analysing what could be going on. I knew next to nothing about VFDs and assumed they were driven by high voltage AC. WRONG. It's only about 10volts to the filaments, and even though it was high frequency AC in this case I was able to...Leave a comment:
-
Re: Weltron 2007 UFO (vintage) - setting bias and crossover
Got DC offset adjusted without too much drama. Vcc is 42 volts, and was able to adjust the offset to 21 volts as per Redwire's instructions. (It was about 18 volts on both channels prior to adjustment).
Bias I couldn't get anywhere near Redwire's calculated numbers. At maximum adjustment I was getting just a fraction over 4mA. Mid point on pot was about 2mA and that was approximately where the pots had been set. So I decided to adjust bias for 2mA because that intuitively seemed about right.Leave a comment:
-
Re: Weltron 2007 UFO (vintage) - setting bias and crossover
Thanks Redwire for the comprehensive "How-To' guide. For some reason they don't include it in their Service Manual.
Yes, it's very much 1970s sexy looking machine. Owner claimed it had strange distortion in one channel, but as is so often the case, when I got it into the shop I couldn't fault it. He requested a re-cap and whatever else. The experts on here said it was a cheap and simple circuit and to leave well enough alone. But owner was insistent he wanted it future-proofed, so I did a complete re-cap...Leave a comment:
-
Re: Yamaha Electric Piano CLP550 no keyboard output
Send a Private Message to PMD who you will find on this thread. He's in Sri Lanka. He and I were discussing getting him to burn me some ROMs for this piano....Leave a comment:
-
Weltron 2007 UFO (vintage) - setting bias and crossover
Currently restoring a Weltron 2007. Have replaced all the small signal and driver transistors in the the power amp stage. In theory I need to reset the bias and crossover. The service manual provides no guidance. Anyone got any thoughts about how to do this?
[These were amazing looking all-in-one systems from the 70s.]...Last edited by dkneyle; 02-26-2022, 06:36 AM. -
Re: MP-3314 multi-voltage plugpack - fails under load
It's driving one of these cheap and nasty Chinese all-in-one Hi-Fi (actually Lo-Fi) units with a turntable, CD player, radio. The specs on the unit say 9V @1500mA.
And what you see in the images is what you get. No heatsink to speak of.
I think you are probably correct. Simply can't supply the required load.
I found a 12V 2A plugpack in my junkbox and gave that a go. It powers up and runs. But there is a oscillation tone coming from the speakers that is reasonably...Leave a comment:
-
MP-3314 multi-voltage plugpack - fails under load
I know these things are only worth a few dollars, so this is perhaps more an intellectual exercise in understanding what is (not) going on here.
The model is marked as MP-3314, sold in our consumer electronics stores, and is variable between 3V and 12V at 1.5A.
Under no load it shows as the appropriate voltage - set currently at 9V. But under load it fails, the LED flashes/blinks as it tries to restart. Meter shows volts come up but fall back with a fraction of a second, repeated continuously.
What would be a typical component that would fail, producing... -
Re: MK1210 chip SMPS based supply - can I fire this up?
I've managed to buy a complete working front panel for this laserplayer. Actually, it is from the clone of the Onkyo, a Pioneer CLD-D504. I'm hoping that by getting the whole front panel with associated electronics attached I'll be able to get the display going with a simple changeover.
What you say about repair shops is all very true. Here in Australia they are almost non-existent because there is no real way to make money.
For your interest, laserplayers never were a technology introduced into Australia. I had...Leave a comment:
-
Re: Yamaha Electric Piano CLP550 no keyboard output
Hi Haydos, If you reach out to some of the guys who are part of this thread they can probably burn the EEPROMs for you. That was what I was going to do if I still had the piano in my possession.
For your interest, I told the keyboard tech at Yamaha Melbourne that we'd recovered the code and it was now floating around on the internet. He's a good bloke, but he didn't seem at all concerned about their intellectual property leaking out....Leave a comment:
-
Re: MK1210 chip SMPS based supply - can I fire this up?
Thanks Momaka for such a comprehensive explanation of how this particular circuit works. Very comprehensive explanation for what I was observing. Answered so many questions, like what that MK1210 was doing there?
On your advice I'll ALWAYS make sure I have everything on the secondary side of a SMPS operational before attempting to fire it up.
Finally spoke to the (actual) owner to get an idea of what had actually occurred. They suffered a "brown out" event and it took out various other HiFi appliances...Leave a comment:
-
Re: Sony KDL-40BX450 LCD. Thermistor gets too hot 10 seconds after turning on the TV
CCFL TV will have an inverter circuit. I'd still be looking closely there for a problem.Leave a comment:
No activity results to display
Leave a comment: