Yamaha RX-V475 DC_PRT H error 100 - Page 1
Forum section: electronics / repair

author: enzo-9552
author_rank: Newbie
timestamp: August 29, 2025, 04:32:29 pm
content: Preface, I have experience repairing electronics - but mostly scientific equipment.I have not repaired audio equipment beforeI purchased a Yamaha RX-V475 off marketplace, and the seller assured me it was working before she took it to her parent's house... They had it stored in the garage (maybe important?)Anyways, when I got it home it was going into protection mode - DC-PRT 100H (high value of 100/255) it also had a PS1 H error.I found the service manual, and opened up the receiver. It was quite dusty, so i cleaned it up best I could with a brush. Since doing a general clean up, PS1 error is gone, but have a consistent DC H error.As a side note, I got a refund as the seller said she was using the receiver before packing up to move out... So this error or damage is recent.Anyways, there is a lot going on here. I have cleaned everything up, and my visual inspection does not find anything obvious (burn marks, bulging caps, etc)... I checked the main transistors on the heat sink and they appear ok (diode checker).While powered on, I found a spot to measure DC_PRT and indeed it was about 1.3V where it should be 0.7 nominal.Since all the boards are stacked, I have not done any live testing on the bottom main board.So preliminary testing: measured resistors and transistors and compared each amplifier channel... so far everything looks good.I took out C2076 as in my experience, electrolytics go bad and can affect powerAt work we have an LCR meter and it is showing about 180uF (spec is 220/10) and losses capacitance as the freq goes up and ESR is close to 1... So I am thinking this could be it...I will swap it in tonight and see what happens.Also - when powering up, I do not measure any voltage on the speaker outputs... I dont know how quickly the relays click on, or if it goes into protection before enabling outputs...When going into service mode - there is nothing on the outputs (again, do the relays turn on?)If anyone has experience fixing the DC_PRT issue I would appreciate any help or guidance.

author: Swake
author_rank: Frequent Contributor
timestamp: August 29, 2025, 07:00:06 pm
content: Quote from: enzo-9552 on August 29, 2025, 04:32:29 pmIf spec is 220µF and you measure only 180µF then it is indeed time to replace it.Please report back after the swap.

author: mbz
author_rank: Contributor
timestamp: August 30, 2025, 05:50:54 am
content: Quote from: enzo-9552 on August 29, 2025, 04:32:29 pmAllowable range is 27-89 (0.35 - 1.15Vdc) so only a small departure, might be the cap/

author: David_AVD
author_rank: Super Contributor
timestamp: August 30, 2025, 09:53:18 pm
content: Check R2204 (100K) which is across C2076. If this goes high in value, the DC_PRT line goes higher. Remove to test or simply replace.Have you checked for any DC offset on the amplifier channels? You can measure between ground (0V, chassis) and one of the bias test point pins on each channel.For PS1 and PS2 errors, replace all of the SMD resistors on tha main amp board and regulator boards. They do fail and can become intermittent.

author: enzo-9552
author_rank: Newbie
timestamp: August 30, 2025, 10:16:36 pm
content: Replacing the cap yielded no difference. I will start digging again and try and get to that resistor... Hopefully this weekend I will get some time again. Thanks for the pointers

author: enzo-9552
author_rank: Newbie
timestamp: August 31, 2025, 10:47:40 pm
content: As mentioned previous, I put everything back together and dc_prt was still at 100.Looking at the schematics, there is another cap C301 on the main digital board. This is a surface mount electrolytic 33/10. Based on my work experience I decided to swap that as well before doing anything else.Once I powered up again, the receiver stays on and going into the service menus my reading is well within spec (59). PS is 050/064/151. PS1 dropped from 81... So all looking very good.Now I am getting a "version error". Not sure why or how to fix it...