Pioneer DEX-P99rs "No EEProm " diagnostic code.

[dmccul2698]

Hello, My head unit developed strange behaviors so I ran the built-in diagnostic package which returned "No EEProm". The service manual says there is no EEProm connected. I approached Pioneer and they said to swap out the DSP board. All said and good but the DSP board is $860 USD. I am hoping someone can help me

1). Understand the schematic and check the connections between the EEProm and DSP
2). Check the functionality of the EEProm

I don't know if this is the unit's problem but it's a place to start.

I have little to no electronic experience but I am a fast learner. I have a decent DMM and a cheap pocket O-scope. After reviewing the manual I have some thoughts but not enough to make intelligent inferences. i have included some clips from the service manual regarding the EEProm (IC651).

[dmccul2698]

Ok, Maybe Im not asking the questions properly. Please refer to the image (Fig. 1) Legs 5,6,1 and 2 go through a resister bank labeled R651. I don't understand the # configuration next to the individual resisters.

Leg 5 is Signal in from DSP?
Leg 2 is Signal out to DSP?
why does Leg 2 go to R654 then to VCC (Protection?)
Leg 1 goes to ROMCSB. What is this?
I don't know what legs 7 and 3 contribute to the circuit.

I will start w some continuity cks. please forward your thoughts about any of this.

[frankusb]

It's a SPI EEPROM. A SPI bus uses 4 signals, clock (SCK from DSP), chip select (/CS from DSP), data in (SI or slave in from DSP) and data out (SO or slave out to DSP). When CS is asserted (low) the EEPROM will accept data on SI every clock cycle (SCK) and potentially output data on SO every clock cycle. WP is write protect.

[dmccul2698]

The original problem from the diagnostic output was " No ROM Correction"(misstated earlier and I cannot edit the post)

When /CS asserts "Low" the EEPROM (IC651) accepts correction from ROM (IC641), correct or not?

If I am correct should I investigate interactions between IC651 and IC641?

I don't know which will be helpful but I am going to include some measurements I took last night, all are a learning experience for me. BTW I would be excited to use my o-scope but I am afraid I could damage the unit. Further thoughts on correct usage would be appreciated knowing I am responsible for all actions and I assume complete liability. in the next post, I will give images with labels to separate the ideas.
I am new to forums and unfamiliar with advanced formatting.

[dmccul2698]

Some measurements. there are some misspellings but I can remember how to spellcheck in paint. I do not know if the lack of continuity is normal. Continuity is seen between( the green side) resister bank R651 and associated pins 94.95,96 and 97 respectively. There is no continuity across R651 to IC601 just resistance of .670k ohms

[dmccul2698]

I have taken a magnified image of the resister if helpful, I did not want to waste space if it is not necessary 😊

[frankusb]

The original problem from the diagnostic output was " No ROM Correction"(misstated earlier and I cannot edit the post)

When /CS asserts "Low" the EEPROM (IC651) accepts correction from ROM (IC641), correct or not?

If I am correct should I investigate interactions between IC651 and IC641?

I would assume you mean "No ROM Connection"?

When /CS is low the EEPROM should be accepting data from pin 95. It's likely commands to set the address to read from but could also be an address to write to as well.

You could verify that the four SPI signals are toggling. If everything toggles except for SO then the EEPROM is not working. CLK, CS and SI are driven by the DSP. The EEPROM toggles SO.

[dmccul2698]

hello everyone, the site does not allow r posting the complete manual so here is the clip of the error from the manual.

[dmccul2698]

Looking around the web, it seems best to test this problem with a 4-channel o-scope. I don't have one of those. Is there another way?

[frankusb]

You would really only need 4 channels if you want to look at all signals at the same time to decode the chip operations. Verify whether each signal toggles individually first.

If the clock speed is low enough you can use a cheap logic analyzer.