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Post by mastertech on May 2, 2022 19:35:52 GMT -5
Yes, bad caps are always in the back of my mind. Have replaced so many over the years I am sick of it.
I scoured these schematics some more (these schematics are the worst I have ever seen, hate them) and I see that the USB CPU is what controls the led and also turns on the main power relay, not the main or sub CPU.
After finding this I have another question. I believe you said that once it is locked up you cannot put it back into standby. So I believe to shut it off you either release the main power switch or unplug it. If so, then my question is, when you plug it back in and/or relatch the main power switch, is it then in standby? and if so, do you have to turn it on the rest of the way with the remote or something else? And does the led go red, yellow, green?
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Post by serafis on May 2, 2022 19:53:38 GMT -5
Yes, bad caps have been a nightmare of mine too! Rejuvenated many amps by replacing electrolytics, especially around regulators.
Interesting that the USB CPU controls the LED and relay, I hadn't noticed that but it makes sense (otherwise how could it reload firmware from USB) - implication may be that main/sub CPU aren't booting.
When power is applied:
- in State 1 (working) it would go into standby (red LED) and need to be turned on with the remote.
- in State 2 (partially working), it would go yellow LED then green (no standby) and remote power button would cause relays to click but not go into standby.
- in State 3 (not working, current state), it goes yellow LED then green and no remote or front panel buttons do anything.
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Post by mastertech on May 2, 2022 20:20:09 GMT -5
It appears as though the main CPU is acting up even in partially working mode. This working and not working does sound like some bad caps. If you are going to be ordering stuff, I would probably also order a couple Eeproms. They are probably cheap and you may still end up going there also if caps don't do the trick.
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Post by serafis on May 2, 2022 20:31:02 GMT -5
OK, Thanks.... I think I have most of the capacitors I'll need in the parts bin. if I order new eeproms, do I need a programmer or anything? I don't know much about that side of things.
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Post by mastertech on May 3, 2022 9:36:13 GMT -5
if I order new eeproms, do I need a programmer or anything? I don't know much about that side of things. Well it is hard to say. In some devices the Eeprom has factory installed firmware that is required to make the CPU function. Without this firmware the device is dead. But, in some devices the Eeprom is only there to hold various information when the device is shut down or access settings during operation. This would mean if the Eeprom failed the device would still function but not correctly. However, I have had devices with shorted Eeproms that would cause it to lock up the CPU and the unit would appear dead. Replacing the shorted Eeprom with a new blank would fix the unit to function and settings would just need to be updated. According to your service manual, this Eeprom is used for retaining system settings at power down. But it is hard to be sure if it also contains firmware or not. |
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Post by serafis on May 4, 2022 19:22:11 GMT -5
I replaced all of the electrolytics on the Power board, and all electrolytics around voltage regulators or ICs on the Input and HDMI boards (how I hate lead-free solder and multi-layer boards!). Powered up and it was completely dead. I found that IC66 which provides ST+5V to the input board was delivering only 4.4V which dropped to 1.9V when connected to the Input Board. I replaced it with a 7805 with some inventive wiring to cater for the different pinout and, after testing, reassembled everything.
Unfortunately no go - turns the mains relay on after 10 seconds (LED yellow, then green), power rails all OK again, but nothing else, just like before. Have tried with a firmware USB, but same behaviour as before. So will try replacing the eeprom (when I get one, which may take a while) but otherwise it's not looking hopeful.
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Post by mastertech on May 4, 2022 20:17:31 GMT -5
Did this include the 2 caps for ic156, 2 caps for ic158 and C715 ?
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Post by serafis on May 4, 2022 23:41:25 GMT -5
Did this include the 2 caps for ic156, 2 caps for ic158 and C715 ? Yes, to all of these (3 caps for IC156: C732, C740 and C749). Also checked the output voltages of these ICs, 3.274 and 3.294 respectively |
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Post by serafis on May 5, 2022 0:41:05 GMT -5
I'm looking at IC164 on P24, marked "2.8V Reset" with output connected to pin 1 of IC162. The output voltage is the same as the input voltage, 3.265V, and there is zero voltage drop across R172. Is this how it should be?
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Post by mastertech on May 5, 2022 10:43:05 GMT -5
IC164 is a reset device, not a regulator. And since ic162 seems to be functioning properly then I would assume it is ok.
If you plug in the unit and leave it on for about 10 to 15 minutes does ic151, ic152 or ic154 get hot? Or any other component for that matter. Feel around for anything hot.
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Post by serafis on May 5, 2022 15:32:47 GMT -5
Nothing on the input board gets hot. IC154 gets a bit warmer than IC151 or IC152, but I could leave my finger on it indefinitely without discomfort. The heatsink on IC66 on the power board gets hotter than the other heatsinks.
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Post by serafis on May 7, 2022 21:15:45 GMT -5
Bit of further testing:
It recognises the insertion of the USB key (USB LED flashes, but then goes out). The USB switch IC163 has SEL=HIGH and OE=LOW which, according to the SM, switches the USB to BOLERO (IC162) for firmware loading, rather than VENICE (DAB/Ethernet Receiver) for music etc. From USB D+ to IC162 pin 79 measures around 25 ohms, as does USB D- to IC162 pin 80. IC163 has 10 ohm resistors either side, so this seems pretty close.
This indicates to me that IC162 has correctly self-booted but has received wrong responses from the rest of the system and so has caused IC63 to switch the USB input to IC162 to attempt system recovery. But that's where it stops. Whatever is supposed to happen next, doesn't.
So I suspect firmware corruption in either IC162 or IC151, but can't think of a way to overcome this. I'm beginning to think this is a lost cause and it may be destined for the landfill, which is a pity.
Any other thoughts? Also, I can't find a direct equivalent for the EEPROM (CVIM24C32WMN6TP) - will any 24C32 eeprom do?
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Post by mastertech on May 8, 2022 16:55:55 GMT -5
If you want to keep doing some testing I am fine with that. I have a little extra time.
Somewhere near ic162 locate these resistors and do a resistance test and give me the readings. Make sure unit is unplugged.
R171, R110, R111, R166, R167
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Post by serafis on May 8, 2022 19:42:34 GMT -5
Somewhere near ic162 locate these resistors and do a resistance test and give me the readings. Make sure unit is unplugged. R171, R110, R111, R166, R167 All these resistors read 0.004 ohms (same as if I join my DMM probes). I've also measured all of the resistors around IC162 and IC151, and they all read within 2% of their marked values. The only anomaly I've found so far is D805 and D806 (top right of P24 between USB_GND and Gnd) which measure as shorts (as do C860 and R682, unsurprisingly given that they're in parallel). Not sure whether this is important or which of these four components may be at fault (if any). |
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Post by mastertech on May 8, 2022 20:58:20 GMT -5
The only anomaly I've found so far is D805 and D806 (top right of P24 between USB_GND and Gnd) which measure as shorts (as do C860 and R682, unsurprisingly given that they're in parallel). Not sure whether this is important or which of these four components may be at fault (if any). This does not appear to be an issue but I will keep it in mind. Next I would like you to try a manual reset of ic162. You will need approximately a 100 ohm resistor with legs. With the unit powered up use the resistor to jump legs 1 (vout) and 3 (vss) of ic164 for about 1/2 to 1 second. While doing this, if you can, look at the green led and listen for the main relay. I would think the relay should release, the led should change color and the relay should relatch and led go back to green. Then observe if there is any change to the unit and try the remote to put it in standby or other functions. |
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