Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Thread Like Summary - 861v4 + HD621 + DSP8000 — No audio any channel, centre PCM NL, comms chain issue

Hi,

I hope someone can help with a persistent and escalating fault on my Meridian system. I'll try to be as precise as possible.

SYSTEM CONFIGURATION
- Processor: Meridian 861v4 (firmware 4.25/4358)
- HDMI interface: Meridian HD621 (recently added)
- Front L/R: Meridian DSP8000 with Performance Pack
- Centre: Meridian DSP8000 with Performance Pack
- Subwoofer: Meridian D55HC repurposed in SW5500 role
- Sources: Kaleidescape Strato E, PS5, plus others via HD621

COMMS CHAIN (DIN/BNC)
861 comms out (DIN-BNC) → Centre DSP8000C → (BNC) → Left DSP8000 → (SpeakerLink) → Right DSP8000 → (BNC-DIN) → SW5500

IMPORTANT NOTE ON COMMS CABLING
The DIN-to-BNC cable running from the 861 to the centre speaker was originally a DIN-to-DIN cable that was cut and resoldered with a BNC connector added by audio electrician. At the time this was done I was not aware of the distinction between M5 (master) and S5 (slave) comms cables and he was unfamiliar with Meridian gear. I do not know whether the original cable was an M5 or S5, or whether the resoldering has affected the pin connections. I am aware this could be significant and would welcome guidance on this specifically.

DIGITAL AUDIO ROUTING (OE12 card)
- D1-2 → Left/Right DSP8000
- D3-4 → Centre DSP8000 (sub daisy-chained from centre)

ORIGINAL PROBLEM
After integrating the HD621, video worked correctly but there was no audio from the centre or sub. Left and right worked fine. Speaker calibration tones worked correctly on all channels including centre and sub.

Diagnosis identified that sources were not correctly assigned to MD1 on the 861, resulting in only 2-channel PCM reaching the processor. Once corrected, the 861 reported MHR Movie6 96k, confirming 6-channel PCM was now arriving. After this correction, the centre speaker began showing PCM NL continuously. Left and right continued to work, no sound to sub. It was identified that the centre DSP8000C was defaulting locally to Left channel and SpeakerLink input. These were changed to Centre and Coax respectively via MConfig but still no success.

COMPLICATING EVENTS
A diagnostic cable swap was then attempted — the D1-2 signal was temporarily fed into the centre speaker's digital input. This caused the system to split into two separate controller domains and no sound worked. After recovery efforts, all speakers now wake together, but audio has been completely lost from all channels including left and right.

CURRENT STATE
- All speakers wake together and display source names ✓
- 861 shows Auto Controller when Clear is pressed ✓
- HD621 video switching works correctly ✓
- No audio from any source on any channel ✗
- No calibration tones from any speaker ✗
- Centre DSP8000C shows PCM NL continuously ✗


STEPS ALREADY TAKEN
- Multiple full mains-off power cycles (3+ minutes)
- MConfig file re-uploaded (confirmed successful)
- 96kHz/24-bit capable flag corrected from No to Yes for all 8 speaker outputs in MConfig — this was set to No for all outputs despite the global Fronts/Rears 96/24 capable flags being set to Yes
- All speaker output types confirmed as DSP in MConfig
- Cabling restored to original routing after diagnostic swap

KEY QUESTIONS
1. With left and right DSP8000s waking and displaying correctly but producing no sound, and no calibration tones from any speaker, is this consistent with a fault on the 861 OE12 digital output card, or is there a configuration state that could cause this?
2. The centre DSP8000 shows PCM NL. D3-4 is confirmed as the output pair feeding the centre. Could the diagnostic cable swap have disturbed the centre speaker's internal input lock state in a way that persists through power cycles?
3. Is the cut-and-resoldered DIN-to-BNC comms cable from the 861 to the centre speaker likely to be causing comms instability, and how can I determine whether it is wired correctly as an M5 master cable?
4. Is there a reliable factory reset procedure for the 861v4 at firmware 4.25 that would clear all stored state? The Display button shows firmware info only and no reset option is apparent.
5. Would moving the comms master from the centre to the left speaker be advisable at this stage?

I have the full MConfig .msl file available if anyone would like to review it.

Many thanks in advance for any guidance.

Cheers
David

If this was a G series (most likely applies to 8 series), would say remove and clean the PCIE style connector on the card with some contact cleaner or isopropyl. Hopefully the card is not failing.