Help!! My Mcintosh c2500 preamp not working

**Audiophilehi** · September 14, 2016, 09:19 PM

Hi, All

I am having a problem with my Mcintosh c2500 preamp. The left and right output level lights are on as well as all the bottom red led lights except for the mute. The display in the center does not light. The unit is frozen. The only way to turn it off is to unplug it. When I plug it in it automatically turns on. I tried resetting as per page 26of manual with no luck.

See below.

Reset of Microprocessors
In the unlikely event the controls of the C2500 stop
functioning, the microprocessors can be reset by performing
the following:
1. Press and hold the STANDBY/ON Push-button for
approximately ten seconds and then release.
2. To switch the C2500 back On press the On
STANDBY/ON Push-button.
Note: This can be performed with the C2500 On or in
the Standby Mode.
Resetting the C2500 to default settings
If it becomes desirable to reset all the adjustable settings
(Setup and Trim Settings) to the factory default
values, perform the following steps:
1. Press both the PROCESSOR and OUTPUT 2
Push-buttons until the Front Panel Display indicates
“FACTORY RESET”.then release the two push-buttons. Several seconds
later the Front Panel Display will indicate “FACTORY
RESET, -COMPLETE-” and the C2500 will
switch Off

**Mike** · September 14, 2016, 09:53 PM

**jdandy** · September 14, 2016, 10:40 PM

Audiophilehi.......Try unplugging the C2500 for more than just a minute or so, like maybe 15 minutes. Then try pressing and holding the STANDBY/ON push-button while you plug the C2500 back into power and hold it for ten seconds to see if that will reset the microprocessor.

Were your trying to update the firmware when this situation popped up?

**Mike** · September 14, 2016, 10:42 PM

Sent from my iPhone using Tapatalk

**Audiophilehi** · September 14, 2016, 11:05 PM

Originally Posted by Double-D

Audiophilehi.......Try unplugging the C2500 for more than just a minute or so, like maybe 15 minutes. Then try pressing and holding the STANDBY/ON push-button while you plug the C2500 back into power and hold it for ten seconds to see if that will reset the microprocessor.

Were your trying to update the firmware when this situation popped up?

HI Dan,

That didn't work. I wasn't attempting any firmware update. It was working fine a few days ago. Really bad timing as I just received the latest Beatles vinyl Mono Box set.

**jdandy** · September 14, 2016, 11:49 PM

Audiophilehi.......Did you experience any outages or surges in utility power? Do you have a surge arrestor installed on your service panel?

I looked at the C2500 schematic and only see a single 800mA time delay fuse, so it isn't some additional internal fuse that has blown. It appears there has been a microprocessor or firmware failure. This is going to require your C2500 to be serviced. I wish I could have been more help.

**Audiophilehi** · September 15, 2016, 09:51 AM

Originally Posted by Double-D

Audiophilehi.......Did you experience any outages or surges in utility power? Do you have a surge arrestor installed on your service panel?

I looked at the C2500 schematic and only see a single 800mA time delay fuse, so it isn't some additional internal fuse that has blown. It appears there has been a microprocessor or firmware failure. This is going to require your C2500 to be serviced. I wish I could have been more help.

Thanks Dan, I was afraid of that. I have the unit plugged into a PS Audio Power Plant Premier. I didn't notice any surges and there was no power outage.

Thanks again!

**Audiophilehi** · September 15, 2016, 06:54 PM

All,

Good news!! I contacted Chuck Hinton at McIntosh and followed the below procedure and all is good again.

Thanks Dan for your help and if Chuck checks in Thanks to you as well.

McIntosh is truly the best!!

a. Disconnect the AC power.
b. Remove the bottom cover – Yes turn the unit over.
c. Locate the main microcontroller. It is the square IC approx. 1cm across on the control PCB.
d. Locate the two buttons adjacent to the microcontroller labeled “PROG” and “RESET”.
e. Press and hold the “PROG” button while also plugging in the AC power cord. This will take some dexterity.
f. Hold the “PROG” button for at least 10 seconds to properly load the default boot loader.
g. After 10 seconds remover the AC power cord and release the button.
h. Re-apply the AC power once again.
i. The unit will be on – sort of… The front panel display will be dark and all the red LEDs will be lit. This is expected. The unit is now in update mode and should accept the firmware update.
j. NOTE: When the update software is run and the unit is discovered, the attached device model will be listed as “unknown”. This is expected. Just answer all prompts in the affirmative.

**jdandy** · September 15, 2016, 08:30 PM

Audiophilehi.......That is fantastic. One more tidbit of useful information to fill away for future use. I am happy for you that McIntosh and Chuck had a solution for the problem that worked.

Happy days are here again.

**Audiophilehi** · September 15, 2016, 08:55 PM

Originally Posted by Double-D

Audiophilehi.......That is fantastic. One more tidbit of useful information to fill away for future use. I am happy for you that McIntosh and Chuck had a solution for the problem that worked.

Happy days are here again.

Thanks Dan!

Happy day's are most definitely here again! Just in time to listen to my just delivered Beatles vinyl mono box set.

Below is the full document for all who need. It's for the C50 but also applied to the C2500.

Solutions to common C50 Software update problems:

1. Choosing a computer
The right computer unfortunately means everything. The proprietary driver used by the IC manufacturer to communicate with the microcontroller has some difficulties running in Windows 7 on an AMD computer. It seems that any other combination works just fine. The good news is that this is only a temporary problem until the IC manufacturer resolves its issues.
If you attempt to perform the update using a WIN7 OS on an AMD computer, the software will cause the C50 to lockup and not recover without removing the bottom cover!!

2. Unlocking a ‘Bricked’ C50
So if you did not heed the warnings above and the C50 is now unresponsive do the following:

a. Disconnect the AC power.
b. Remove the bottom cover – Yes turn the unit over.
c. Locate the main microcontroller. It is the square IC approx. 1cm across on the control PCB.
d. Locate the two buttons adjacent to the microcontroller labeled “PROG” and “RESET”.
e. Press and hold the “PROG” button while also plugging in the AC power cord. This will take some dexterity.
f. Hold the “PROG” button for at least 10 seconds to properly load the default boot loader.
g. After 10 seconds remover the AC power cord and release the button.
h. Re-apply the AC power once again.
i. The unit will be on – sort of… The front panel display will be dark and all the red LEDs will be lit. This is expected. The unit is now in update mode and should accept the firmware update.
j. NOTE: When the update software is run and the unit is discovered, the attached device model will be listed as “unknown”. This is expected. Just answer all prompts in the affirmative.

3. I loaded the software and connected the C50 but the computer could not find the drivers:
When Windows tries to find the driver and fails it will give the user two options:

a. Find the drivers automatically (which just failed).
b. Allow the user to specify the location of the driver.
Select the second option and browse to the following location (this may vary depending on OS): C:\Program Files (x86)\McIntosh Laboratory\McIntosh C50-V2.00 Firmware Update\driver
Now let Windows load the driver.

4. I loaded the software and connected the C50 but the computer loaded a GPS Camera Driver:
If Windows does not find the update drivers on its own and the computer is internet connected, it will automatically look elsewhere for a driver.
For this application we are using the default CDC driver provided by the microcontroller IC manufacturer. Unfortunately, there is a GPS Camera manufacturer who did the same thing but also registered theirs with Microsoft.
The good news is that it doesn’t matter. It is precisely the same driver under a different name and will work fine with our updater.

5. I loaded the software, put the C50 in update mode, connected the two via USB cable, and discovered and loaded the correct driver but the updater still says “scanning”.

This is actually a rare occurrence but it can happen. By all accounts everything should work but does not. Follow these steps in this order and retry along the way:

a. Exit the updater and disconnect the C50.
b. Restart the computer ( let it fully boot up)
c. Reconnect the C50 (listen for the tone or verify the driver is loaded in device manager)
d. Restart the updater.
e. If this fixes the problem you are done.
f. If the updater is still stuck in “scanning”, go to item #2 above and follow the procedure for unlocking the C50.

**NorthernEscape** · January 21, 2017, 10:57 PM

Got a brand new c2500, and was playing around with settings,
nothing connected, and except for the fact that the front panel on/standby switch would not turn on the unit, but the remote did, everything seemed to work, i.e. Changing settings etc.. Just for fun hooked up my iPhone thru a Dragonfly Red, and headphones, and this worked fine.

Today I was connecting it up For real integration into audio system, first setting and using it as a passthru for my Pioneer Sc-lx701 avr, and connecting the c2500 to my xpa-1 monoblock/B&W cm10s2. I go to the home theater pass through trigger to work turning the unit on. And that turns it on----Now however, nothing works on the front panel or the remote. I can only get the unit to turn on and off using the trigger, i.e. through the passthru rear trigger jack, nothing else ----and I disconnected everything when I first noticed that nothing worked.

i tried the two resets in the manual and as above, but not the turn over, setereset and program as described above, because I am also little unclear what those steps are.

Can anyone clarify that reset mechanism for me? Also I use MacBook IOS, not window although if pushed I must have some old cpus with windows, maybe, somewhere....help if possible?

thanks

**joeinid** · January 22, 2017, 11:22 AM

Welcome to the forum forum NorthernEscape, thank you for joining.

**Audiophilehi** · January 22, 2017, 01:16 PM

Welcome to AS!

Do you have the latest Firmware update? You can download from McIntosh website. Must be on Windows PC. then see post #10 in this thread. That's what worked for me when my c2500 was hosed up. Good Luck!

**NorthernEscape** · February 10, 2017, 07:15 PM

Welll........

Thank you so much for responding. I called Chuck Hinton, at Macintosh and lo and behold, he told me to go ahead, basically as described above. He forwarded to me new software driver set for the C 2500 and I dug up an old Windows laptop. Took off the bottom, found and hit the reset button, and managed to load the new software. Hit the reset button and things began to light up

.

However, I had tried the on/standby button when I first got the unit, and nothing happened. The button felt sticky and "funny", and was definitely different from the other front panel buttons. With the bottom panel still removed, I tried that button and noticed that the circuit board to which the button functions, had an obvious deviation away from the front panel, and hence "locked out" because of this increased extension. The board is not really well supported or tethered at this end. Chuck says he has seen this in about 10 or so c2500 preamps. To fix I would need to take in for repair, but there is really no good dealer here( I moved the amp from where I bought it, so the original dealer can't really help. Since the remote works fine, and I wanted to get up and going finally with this new pre, I buttoned it up and will use only the rrremote, and not take a chance on the button locking, which it would if used. So kind of a design fault by Mac, that should be corrected, and I wonder if they changed that in the c2600? Anybody know?

Thanks....

**Audiophilehi** · February 11, 2017, 08:52 PM

Originally Posted by NorthernEscape

Welll........

Thank you so much for responding. I called Chuck Hinton, at Macintosh and lo and behold, he told me to go ahead, basically as described above. He forwarded to me new software driver set for the C 2500 and I dug up an old Windows laptop. Took off the bottom, found and hit the reset button, and managed to load the new software. Hit the reset button and things began to light up

.

However, I had tried the on/standby button when I first got the unit, and nothing happened. The button felt sticky and "funny", and was definitely different from the other front panel buttons. With the bottom panel still removed, I tried that button and noticed that the circuit board to which the button functions, had an obvious deviation away from the front panel, and hence "locked out" because of this increased extension. The board is not really well supported or tethered at this end. Chuck says he has seen this in about 10 or so c2500 preamps. To fix I would need to take in for repair, but there is really no good dealer here( I moved the amp from where I bought it, so the original dealer can't really help. Since the remote works fine, and I wanted to get up and going finally with this new pre, I buttoned it up and will use only the rrremote, and not take a chance on the button locking, which it would if used. So kind of a design fault by Mac, that should be corrected, and I wonder if they changed that in the c2600? Anybody know?

Thanks....

I have the same issue with my on/standby button as well. I've using the remote as well. Guess I'll get around to getting it repaired. Hate to be without it.

Funny thing it works to reset the microprocessors when the Dac freezes. Go figure!

**petek** · December 18, 2018, 11:13 PM

Mine just developed the problem. Both Mc and AC sent me the firmware but it was a no go. Even though I made both places aware that I knew about the removal of the bottom and the prog button to reset, neither
gave me that option. I sent to AC this morning which promises a quick turnaround. The 160$ shipping is ouch though.

**petek** · January 11, 2019, 08:17 PM

Been back for while now. Un locked and upgraded. I wonder how it locked up in the 1st place.

**Audiophilehi** · January 11, 2019, 09:39 PM

Originally Posted by petek

Been back for while now. Un locked and upgraded. I wonder how it locked up in the 1st place.

I can’t say for sure but since I preformed the procedure and did the firmware upgrade my c2500 has worked flawlessly without any incident.

**petek** · November 1, 2019, 09:21 PM

Originally Posted by Audiophilehi

I can’t say for sure but since I preformed the procedure and did the firmware upgrade my c2500 has worked flawlessly without any incident.

Came home tonight and same issue.
It seems like I get exactly 10 months use and then same lock up occurs.

**MG Music** · January 26, 2020, 07:34 PM

Hi Paul, same thing just happened to my C2500. I did as you instructed but still locked up. Blue meters are lit, all red lights are on except mute. I did the reset - pressed PROG button, etc. How long did you have to wait before the unit came back on? Thanks

**petek** · February 4, 2020, 04:36 PM

I forgot to update this 2d occurrence. Turn around was very quick again..less than 5 days and with AC covering shipping charge both ways. This time they sent me a different C2500 unit.

Now last night this unit portrayed the same behavior momentarily but I did get it to function by turning off the Dectet and switching it on. The rest of the items connected to the Dectet was functioning fine however.

The unit seems to have its peculiarities. Maybe it hates to play with power conditioners.

I know one of the AC guys has problems with his mcIntosh preamp too as he told me he has to keep the firmware upgrade ready to go for his unit at home.

Originally Posted by petek

Came home tonight and same issue.
It seems like I get exactly 10 months use and then same lock up occurs.

**Penthouse-D** · February 4, 2020, 04:51 PM

ugh..

**joeinid** · February 4, 2020, 05:59 PM

Welcome to the forum!

Originally Posted by MG Music

Hi Paul, same thing just happened to my C2500. I did as you instructed but still locked up. Blue meters are lit, all red lights are on except mute. I did the reset - pressed PROG button, etc. How long did you have to wait before the unit came back on? Thanks

**Bones13** · February 4, 2020, 06:20 PM

Check your cables for shorts, even intermittent ones.

I had several issues with some of my boxes, including repairs to a power supply on a pre-amp, and had a DAC returned with no fault. Turns out it was a commercial XLR cable, from a well known company, with an intermittent short, that was at fault for my 2 problems. No issues since replacing it.

**Scotty** · February 4, 2020, 07:19 PM

I have a Mac C2300 pre in my home theater system. A few years ago, I got upgradeitus, and bought a C2500 from Audio Classics. When I received the C2500, I got a continual buzz, like a grounding problem, and I could never resolve it. Audio Classics graciously took the unit back and refunded my $$, and I have been very happy with the problem-free C2300 since then. Not sure whats going on with the C2500.

**Scotty** · February 4, 2020, 07:24 PM

I might add that I am also a big Chuck Hinton fan - he has helped me, very promptly and professionally, with several situations with my vintage MC225 amps. I hope he gives us all his cell phone number when he retires.

**Audiophilehi** · February 4, 2020, 08:16 PM

Originally Posted by MG Music

Hi Paul, same thing just happened to my C2500. I did as you instructed but still locked up. Blue meters are lit, all red lights are on except mute. I did the reset - pressed PROG button, etc. How long did you have to wait before the unit came back on? Thanks

After following the procedure my c2500 came on right away. It’s been awhil but if I remember correctly there are 2 Prog buttons in the c2500. There’s a Prog button just to the right of the reset button and another up a bit or north of it.

**esalvg** · February 14, 2021, 11:36 AM

Hey every body! Any one know the way to get firmeware?

**esalvg** · February 14, 2021, 11:37 AM

Today I follow the instruction and forgot that need firmware...Any body Could help me?

**Pigreco3** · July 25, 2022, 01:22 PM

Hi guys,
I have the same issue in my C2500 don't work Display, remain on all the red leds and Vumeters.
Could you help me for fixed the issue.
Thanks

**Audiophilehi** · July 25, 2022, 03:15 PM

See post #8

a. Disconnect the AC power.
b. Remove the bottom cover – Yes turn the unit over.
c. Locate the main microcontroller. It is the square IC approx. 1cm across on the control PCB.
d. Locate the two buttons adjacent to the microcontroller labeled “PROG” and “RESET”.
e. Press and hold the “PROG” button while also plugging in the AC power cord. This will take some dexterity.
f. Hold the “PROG” button for at least 10 seconds to properly load the default boot loader.
g. After 10 seconds remover the AC power cord and release the button.
h. Re-apply the AC power once again.
i. The unit will be on – sort of… The front panel display will be dark and all the red LEDs will be lit. This is expected. The unit is now in update mode and should accept the firmware update.
j. NOTE: When the update software is run and the unit is discovered, the attached device model will be listed as “unknown”. This is expected. Just answer all prompts in the affirmative.

**Pigreco3** · July 25, 2022, 04:52 PM

Hi NorthernEscape,
I have read that you have the files for reload the firmware, I have contact Chuck Hilton but him can't send me files, I don't why.
Could you send me these files by PM?
I appreciate a lot your help, thanks in advance

**Pigreco3** · September 3, 2022, 02:24 PM

Upgrade my situation, at the end I have sent to service assistance, at the moment there are broken some ICs of the digital card and another issue in the main PCB.
Then will be cleaning front glass whit special procedure, it has an incoming of oxidation.
I haven't now exactly information about the two issues, I keep in touch.
Bye

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Help!! My Mcintosh c2500 preamp not working

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