CARVER C-500 Repair Questions....

[Dallas797 12]

Hi Everyone,

I am new to this site when hope I landed to the right place for Carver matter and have been reading some valuable posts & info about Carver amplifiers that I have one particular C-500 model. It's been quite some time since I had it but never had connected to any system until recently when interconnected it with the preamp.  It sounded great for no more/less 5 minutes then the Left-Channel started with cracking sound intermittently distorted then completely silent.  By checking the 3 fuses, the AC line is good while the Left-Channel fuse was already burned!....At that point the R-Channel was still functioning but I didn't have time to check further around early 2022... Last week, turned it on and heard a a light pop which is the R-Channel fuse!.... Fast forward, I checked the power transistors and it seems to be at least one if not more is/are shorted!... I would like to see if I could learn from anyone who has experiences with C-500 repair and I have some questions below if anyone could help?

1- What is the proprietary code name of  the Power Trans Motorola C1000 (7952) equivalent to Motorola's conventional # MJ15024?

2- What source could I purchase the transistors nowadays with reliable (original) trans

3- In some post I read, someone mentioned to replace all 20....while my C-500 has 16x C1000 and 4x RCA410 (7916), what does that mean?

Appreciated!

[BobTFM35 2,251]

@Dallas797 Welcome to the Carver site!!

 

I am no expert on this amp nor any other for that matter. 

 

In looking at the service manual that is available here on the Carver Site I can possibly see why that poster mentioned to replace all 20. The RCA410 comes before the C1000's, so it might have some control over the four, so replacement might be necessary. That one looks to be some sort of gate keeper or gate driver for the other four in the line. Please someone correct me if I'm wrong.

 

Here is a picture of the back of the C500 showing the items and hopefully what you have on yours,

 

 

I don't have any cross reference on what to replace those items with.

 

I would reach out to Greg here Carver Amplifiers - Services - Nelion Audio to see if he can restore this amp.

 

I hope someone comes along to better help in the repair of your unit and give you guidance.

 

Wish you well with the repair of your unit.

 

Edited November 9 by BobTFM35

[AndrewJohn 9,170]

Welcome, @Dallas797, so glad you found us.

 

At the seminal days of Carver Corp (post Phase Linear), Bob modeled this amp after the PL-400, with additional row of transistors.  Like other designs, Bob Carver used existing parts - many of which were for automotive applications.

 

By now, some of these are no longer available, so it becomes a task of finding more recent replacements that fit the purpose.

 

there is a thread on c1000 on DIY Audio..., https://www.diyaudio.com/community/threads/replacement-transistors-for-long-tailed-pair-please.326664/

 

A little more googling, might turn up more discussions.

 

Another source would be to go to White Oak Phase Linear, as they provide full upgrade kits to the Phase Linear precursor to this amp..., just google WOPL.  I'm short of time at the moment, or I'd look a bit more for you.

 

And, someone here might also have the answer.

[Dallas797 12]

Hi AndrewJohn 

 

Thank you and I will search based on the info you provided. Have a great weekend! 

[Dallas797 12]

BobTFM35

 

Thank you and I will search based on the info you provided about the upgrade.

[AndrewJohn 9,170]

@Dallas797, be sure to come back here, and post what you found, and where.  

 

There aren't very many threads on the c-500 amp, and your experience may help others.

 

We LOVE pictures, share some of your gear if you can 😉 

[jvandyke_texas 436]

I worked on one of these for a friend.  It was formerly Bill D's amp.

There were wrong value resistors stuffed in one channel around the bias trim pot.

I suggest checking all part values against schematic.

We replaced all output transistors, but I don't have records what we used.