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Re: Kenwood CS-4035 Oscilloscope repair questions
So, when going to measure across the cap it became apparent that there was abreak in the trace where the cap had been. Fortunately it was on the Gnd pin side which makes reconenction easier.
It'll have to wait a few hours now though as the day has arrived.
I'll also take some readings at the pin holes with the IC removed and then we can compare how much the hybrid is affecting things.
Back laterComment
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Re: Kenwood CS-4035 Oscilloscope repair questions
Apologies for the delayed response but had an accident and lost a day.
It reads -4.9v
Testing the zener with a component tester comes back as 5.2v
Double checked the voltages just now and that is what they are...What really doesn't make much sense is pin 11 (-8V feedback pot) reads more negative when pin 10 is more positive.
I suppose the next step must be to replace the op-amp?Comment
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Re: Kenwood CS-4035 Oscilloscope repair questions
Quick progress report on the Kenwood KMA 01 Hybrid IC repair
Replaced the TL 072 Op-Amp and now have variation on the -8 voltage.
It currently swings from -9.50 at one extreme, down to -8.86 around the middle region, and back up to -9.50v at the other extremity.
I am hoping that the voltage is high due to no load on the output, however, we do seem to be getting somewhere with this hybrid IC.
The voltage across the capacitor is now 5.03v (the zener is 5.1)
Gonna now move on to the main board and see if whatever is bringing the rails down can't be located and resolved.
Wish me luck!Comment
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Re: Kenwood CS-4035 Oscilloscope repair questions
Excellent news to report...
These Kenwood Cs 40xx series are repairable.
The scope is fixed and working!!!
The reference voltage is now adjusting properly, so just need to calibrate it.
Thanks for the help and suggestions.
Now I have to get the second one done, and I think it only right to document and photograph the repair process of the KMA01 on that unit and post it on BadCaps for future reference.Last edited by Crystaleyes; 05-08-2022, 04:23 PM.Comment
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Re: Kenwood CS-4035 Oscilloscope repair questions
Hey that's great news
I could only see a few voltage readings implying the IC was bad.Comment
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Re: Kenwood CS-4035 Oscilloscope repair questions
Hi fella.
Yeah, I'm chuffed.
On other threads people had given up on finding the IC's. The general vibe seemed to be to scrap the Kenwood scopes, but it was straightforward on this one, even if I still don't understand exactly how it all works.
These two scopes here have had considerable repairs and tweaks and the short on the main board turned out to be where whoever had changed an electrolytic, had bent a leg (to hold it for soldering) and had almost invisibly shorted that to Gnd.
All good now, just calibration and some noisy switches to resolve.
Big respect and thanks to you and stj. You have literally saved two scopes from the scrapyard
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Re: Kenwood CS-4035 Oscilloscope repair questions
i knew the hybrids would be bad.
in the arcade business Konami uses ceramic hybrids with smd electrolytics on them - and they ALL fail!!Comment
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Hello
I have now same problem with -8 V adjust
Pls check power supply ac from transformer
on 120 V ac have 87 Vac - 157 Vac - 9,51 VacComment
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I am looking at an A2337 and found this for the order of power rails and what they do. Can this be confirmed before I dive into hunting down power rails that do not exist or are not neccisary?
- PPBUS_G3H (12.6V-12.8V)
- This is the main power rail that supplies power to the entire system. Check this rail first, as it must be present for other power rails to work.
- PP3V42_G3H (3.42V)
- This power rail is derived from PPBUS_G3H and is used to power the SMC (System Management Controller) and other essential circuits. It should be present if PPBUS_G3H is working correctly.
- PPVRTC_G3H (3.3V)
- This
- PPBUS_G3H (12.6V-12.8V)
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Hello all. I'll try to keep this short. I have no knowledge of electronics. I can use a multimeter and am familiar with caps to some extent. I bought a Kenwood KR-6030 vintage stereo. It need work and so I thought I would recap the thing since I get power to the on switch but nothing else is working. No lights, no sound and so forth. I went to Mouser to order caps and I find I am way over my head. I not only do not know the type of capacitors I need but Mouser and digikey do not accept Kenwood part numbers. I have the info such as 220uF 63v and such but no place to put it. I could buy a recap...08-08-2025, 03:16 AM -
Hello everyone,
I'm currently diagnosing a MacBook Pro A1707 motherboard that does not power on. I've gathered some data but am stuck and need expert advice.
Note that i'm a beginner in electronics and i'm trying to learn while trying to repair this macbook that my work gave me. I'm really curious and love understanding how thing works and i already learned so much.
Only one usb c port is taking 20v and have 12.5v on PPBUS_G3H. when trying other ports, 2 are not going to 20v and one is going to 20v but the CD3215 is getting really hot.
Observations... -
Hello.
I have jut got my first analogue oscilloscope. An Isotech 620 20MHz.
I want to learn how not to damage it, and I found instructions on the internet obscure.
They talk about ground, earth, floating ground, this, that....
But they don't actually say anything anything useful so far.
I want to know:
Don't connect exactly this to exactly there or it blows up.
For example, I am tracing a signal from a function generator in an audio amp, or testing for voltages in different parts of a circuit.
I want to know what not to connect... -
Hello there, does anyone have info about AMD Ryzen 5 7535hs power rails or an schematics from a compatible CPU?. I have a quanta G3PR from a HP victus laptop, I suspect cpu is damaged but I would like to know what power rail is the one I guess is damaged. There are 4 coils aprox 4.2 ohm to gnd in parallel next to CPU (I guess vcore) ,one coil same size next to those 4 around 0.7ohms to gnd (damaged rail I guess), and other two smaller I guess associated to less current power rails for CPU logic purposes. Anyone have more specific info? I attached picture.
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