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DavidBelgium
Posts: 9
Joined: Sat Nov 15, 2014 1:11 am

Post by DavidBelgium »

Andy,

I removed ALL diodes at the secondary and checked them each with a lamp and a PSU in forward and reverse direction. None of them was broken.

I also injected the respective output voltages by means of an external lab powersupply and measured at the same time the current consumed and the charge/discharge cycle of every capacitor. All currents are normal (what is wasted in the discharge resistors) and the caps are all fine. It should be as they are all new.

I'm now back looking at the primary side and that's for me unknown terrain given that the datasheets of regulator KA1M0680 are very little detailed on the functioning.

I checked the VCC circuit resistors after having them soldered out (R1/R3) Both are fine and perfectly in spec.

When I measure at the cathode of D2 (VCC), I see voltages between 10,4 and 14.8V. Ramp up from 10.4 to 14.8 in 136ms and ramp down in 17.6ms.
So total period = 153.6ms = 6.5 Hz, which is well below the oscillating frequency listed in the datasheet (+- 65Khz)

But as the voltage on D2/VCC/C9 + is sawtooth like, I presume the thing wants to start but fails to (overload/overtemp/no feedback/...)
The coil seems to be energized for a brief period hence the output voltages at the secondary are also considerably lower than expected ; about 1/3 to 1/4th of what you would expect.
On the anode of D1, I see that the voltage is 312, slowly ramping up to 320V and then peaks to 356V for a duration of 15-20ms. This happens every 150ms in line what I measure on D2. So the FET in U1 seems to be on for 130ms and then is off for 20ms.

The heatsink is cold, so overheating can be excluded
C7/C9/C24 were also new elcos, so I will exclude that too
I also checked C6 and C8 with an LCR meter. Their capacity is ok and the resistance not measurable.


The startup treshold for a KA1M0680RB is between 14 and 16V an typically 15V. So the top of 14.8V is just or just not enough to start the PSU. Maybe it browns out all the time.

Leaves me:
-Check the transformer, but how to do that in a correct way
-Check the shunt regulator U2
-Check the optocoupler
-Change the U1 component

I just don't understand how the chip U1 works and I don't have anything to compare it with.
All switched PSU's I have laying around use other components for the oscillator and other feedback systems.

I might try to order a new U1 chip, but they seem to be made of unobtainium and are considered obsolete.

Any hints/comparable measurements are welcome.
alan_m
Frequent contributor
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Joined: Wed Oct 18, 2006 12:11 am

Post by alan_m »

DavidBelgium wrote:
I'm now back looking at the primary side and that's for me unknown terrain given that the datasheets of regulator KA1M0680 are very little detailed on the functioning.

.

Application note
ftp://radiozona.myftp.org/radiotehnika/ ... n-4104.pdf
Ex Toppy 5800 user - now migrated to Xtrend ET10000 Enigma 2 box with 2 terrestrial and 2 satellite tuners. Second box Zgemma H9S (Enigma 2, satellite)
DavidBelgium
Posts: 9
Joined: Sat Nov 15, 2014 1:11 am

Post by DavidBelgium »

Thanks Alan

The link was dead however I found another one thanks to the name of the file

https://www.usbid.com/datasheets/usbid/ ... n-4104.pdf
DavidBelgium
Posts: 9
Joined: Sat Nov 15, 2014 1:11 am

Post by DavidBelgium »

alan_m wrote:
DavidBelgium wrote:
I'm now back looking at the primary side and that's for me unknown terrain given that the datasheets of regulator KA1M0680 are very little detailed on the functioning.

.


Looked at the old U1 that I replaced when I changed the caps. There was a short between Fbk and VCC and as result of that, the internal voltage sources are broken.
Then replaced optocoupler, the snubber cap C6, Diode D1 and C8 too.

Soldered out the new U1 and when applying VCC at 15V, I get a nice 7.5V on pen 4(Feedback) and a nice 5V on pen 5(soft start) and a the current is approx 0.01A. When I drop VCC around 9.8 it stops consuming current, so I think it shuts down more or less as indicated in the datasheet. So it seems fine imho.

So except for the transformer, inductors, some resistors and the shunt regulator U2, I almost replaced or checked the entire psu.

I could not imagine that T1 would be gone.
Somebody a spare lying around ?
andyfras
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Joined: Mon Jul 25, 2005 2:41 pm
Location: Fleet, Hampshire
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Post by andyfras »

DavidBelgium wrote:Somebody a spare lying around ?
I can offer an exchange PSU - I like a challenge.
Toppy PSU repair service or capacitor kits for DIY available - PM me for details.
MyStuff 6.6 : Little Clock : MHEGOnOff : Extend : EPG2MEI : SecCache : EIT_Sub : TSSaver : Prune EPG
Channel Organiser : Tap Commander : HDD Info : PCControl : Signal Monitor : MyInfo
URC-7555 remote: TF5800 320GB 2.5", Recommended_5800.tfd + CfPePsScUUuWfZ
DavidBelgium
Posts: 9
Joined: Sat Nov 15, 2014 1:11 am

Post by DavidBelgium »

andyfras wrote:
DavidBelgium wrote:Somebody a spare lying around ?
I can offer an exchange PSU - I like a challenge.
Andy,

Can you give me a quote P&P included.
It's not mine, so I have to check with the owner if he is willing to spend any money on "old" hardware
andyfras
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Post by andyfras »

I have recently repaired an Icecrypt T2400 PSU for a forum member. It uses the poor quality Sam Young capacitors as used in the Toppy.

If anyone is interested, I could provide a kit.
Toppy PSU repair service or capacitor kits for DIY available - PM me for details.
MyStuff 6.6 : Little Clock : MHEGOnOff : Extend : EPG2MEI : SecCache : EIT_Sub : TSSaver : Prune EPG
Channel Organiser : Tap Commander : HDD Info : PCControl : Signal Monitor : MyInfo
URC-7555 remote: TF5800 320GB 2.5", Recommended_5800.tfd + CfPePsScUUuWfZ
arrow57
Regular contributor
Posts: 27
Joined: Sat Jun 27, 2015 8:33 pm

Capacitor set to repair my TF5810

Post by arrow57 »

andyfras wrote:My website has information on every Toppy fault that I have come across and found a solution to; including self-inflicted.
Hi, my treasured toppy that has served me well for many many years is failing, the signal is becoming ever more pixelated and fragmented. I am assuming conventional wisdom dictates a capacitor replacement.
Do you or anyone have a set I could purchase, I have had several toppys over the years including one from Australia ( long story) and would be devastated to have to bury my last remaining toppy.
Regards arrow57
arrow57
andyfras
Frequent contributor
Posts: 3484
Joined: Mon Jul 25, 2005 2:41 pm
Location: Fleet, Hampshire
Contact:

Post by andyfras »

PM sent.
Toppy PSU repair service or capacitor kits for DIY available - PM me for details.
MyStuff 6.6 : Little Clock : MHEGOnOff : Extend : EPG2MEI : SecCache : EIT_Sub : TSSaver : Prune EPG
Channel Organiser : Tap Commander : HDD Info : PCControl : Signal Monitor : MyInfo
URC-7555 remote: TF5800 320GB 2.5", Recommended_5800.tfd + CfPePsScUUuWfZ
arrow57
Regular contributor
Posts: 27
Joined: Sat Jun 27, 2015 8:33 pm

Post by arrow57 »

andyfras wrote:PM sent.
Hi, received new capacitor set, replaced all of them and yayyyy my tf5810 is as good as new, thanks Andy.
arrow57
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