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.

[dmccul2698]

The EEPROM IC 651 takes ROM correction from IC 641. IC 641 is not offered for purchase from Pioneer. You can only source it by purchasing the PCB @ $860. There are more ICs not offered for this unit. Is this a common practice in the industry? IS there a way to source a doner chip?

[dmccul2698]

I'm waiting for the analyzer to come from China. In the meantime, I wanted to check out IC 641. Its got the pads on the top side, I thought it was through the board but it is not! There is nothing on the other side of the board in that place but a bunch of labeling for the chipsets that are on side B.

[dmccul2698]

In the first image I posted, the diagram shows IC 641 labeled "NM". I went to look for it and its not there. I am missing something.

[lotas]

"NM" this may be missing components in the circuit (not obligatory)

[dmccul2698]

Hello everyone, sorry for the delay in the follow-up.
I was able to obtain a 341A SO8 chip reader and used the AsProgrammer software to create two .bin files of IC651 (EEPROM). Using Guify software, I confirmed there were no differences between the two files. Based on this, I am assuming IC651 is functioning correctly.
Next, I connected the unit to power, fingers crossed, and used a D-shell single-channel oscilloscope to test voltages. I observed that the EEPROM is receiving 3.5V at pin 8. There are signals present at pins 1, 2, 3, and 5, but no signal at pin 6 (SCK). A quick Google search indicated that an EEPROM chip without a clock signal cannot operate properly.
At this point, I shifted my focus to IC601 (the CPU) and checked pins 94 through 97:

• Pins 95, 96, and 97 tested good.
• However, pin 94 (ROMSCK) showed no signal.

I located a datasheet for the M32C chip, but given my current level of understanding, it didn't clarify the acronyms or functions as I'd hoped. From examining the diagram, it appears that ROMSCK is not shared with any of the buses. Is ROMSCK generated directly by the CPU?
With no clear direction, I did some additional probing on IC601 and found the following:

• Pin 1 (BSO, output): No signal
• Pin 2 (BSCK, output): Signal present
• Pin 7 (DSPCLK, output to DSP Vol Bus): No signal
• Pin 18 (ROMDATA, output): Signal present
• Pin 42 (CLK, output): No signal
• Pin 43 (BUSY, output): No signal

Based on these findings, I suspect the CPU is faulty. My question is: Have I overlooked anything in my workup? Any insights would be greatly appreciated!

[stj]

NM is a prefix used by National Semiconductor on their chips.
that pinout is a 93'series so it probably says "NM93LC???" on it.

[lotas]

NM is a prefix used by National Semiconductor on their chips.
that pinout is a 93'series so it probably says "NM93LC???" on it.

NM

[dmccul2698]

Thank you for your input, STj. A note on the schematic clarified the NM abbreviation. NM stands for Non-Mounted. It's a placeholder for a component needed for the board's construction, testing, etc., but it serves no purpose in the end product and is removed before the unit is sold, as I have been told.