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nicrt
Joined: 12 Nov 2021
Posts: 3
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| Posted: Fri Nov 12, 2021 9:25 pm Post subject: Sony G70 error 29 diagnosis |
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Hello there!
A friend of mine got a used VPH-G70QMG (Mfg Oct 1997) showing error 29 which seem to be related to the B board.
We replugged all the connectors but the error still persists. Since the boards are hard to find and he has some electronic skills (multimeter, soldering, hot air station, oscilloscope): Do you know which parts typically fail on these RGB boards?
It might be useful to (carefully) measure the voltages.
Do ICs fail, or voltage regulators? Large caps look good.
And is the error 29 also displayed when the other B according boards are faulty (BA, BC, BE etc.)
I already asked in the Buy & Sell for a replacement one.
Thank you in advance
Nico
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Boet
Joined: 10 Jan 2012
Posts: 30
Location: Netherlands
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| Posted: Thu Nov 25, 2021 3:53 pm Post subject: |
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Hi Nico,
Do you have the service manual? If not, you'll be able to find it for sale for under US$ 10 on some websites.
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nicrt
Joined: 12 Nov 2021
Posts: 3
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| Posted: Wed Dec 01, 2021 8:38 am Post subject: |
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Thanks Boet, yes we found the manual for free at Elektrotanya: https://elektrotanya.com/sony_vph_g70_sm.zip/download.html
The problem has been solved, it was a defective linear regulator IC611 type NJM78M09FA on the B board which failed to deliver 9 V although there was no short.
It's undervoltage caused the IC607 (MAX8213) correctly not to ground the "A9 B PROT" which results in error 29.
If you have the same error, it makes sense to check if all the voltages inputting IC607 are OK.
I attached the service manual snipped but in my opinion there's a typo: IC609 is not a 9 V regulator like IC611 but a 12 V regulator like IC610.
We discussed it in a different forum, if anybody is interested I can give you the link (German language).
Replacing the regulator IC611 made the projector run - stunning picture!
Nico
| Description: |
| IC611 type NJM78M09FA failing to deliver stable 9 V |
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| Description: |
| IC607 (MAX8213) voltage monitor; IC609 is not a 9 V regulator like IC611 but a 12 V regulator like IC610 |
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Boet
Joined: 10 Jan 2012
Posts: 30
Location: Netherlands
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| Posted: Fri Dec 10, 2021 9:30 pm Post subject: |
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Good to hear it's fixed. Luckily it was just an L78Mxx series voltage regulator, not an obsolete or custom part.
Yes, I'd like to look around on the German forum as well. Reading my neighbour's language isn't a problem, writing it on the other hand... 
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