New to the Site. Inherited my dad's Carver and Hafler equipment and am having some intermittent issues.

[Benjaminsswanson 11]

Hi,

 

My dad bought some Carver stuff back when I was about 10 years old and now I have some of it in my living room as a 43 year old. I am currently utilizing the HR772 and 90% of the time it is working great. Occasionally though, it will turn off a few seconds after powering up. I have it powering some Hafler Model 400 towers. I also have a Hafler DH 500 but it is giving me some trouble too. Dad used the HR772 to run some JBL L36s for a while, then the Hafler Model 400s. He borrowed a couple of my Kenwood L-07ms for a bit and then we found a DH 500 for him. When using the DH 500, he used the HR 772 as his preamp. This was my intention when I inherited them, but the DH 500 needs some work. In the meantime I have been using the HR772. Now it is giving me some trouble. I am mechanical engineer by trade and am comfortable with tools and can brush up a bit to read some electrical schematics, but make no claims to be an electronics expert. I have a Dim Bulb Tester that I built a while back, but haven't plugged it into the Carver yet. I have a soldering iron as well. I also am open to recommendations on shops if that seems like a better route. I live in Atlantic Beach FL (basically Jacksonville). Thanks in advance for any direction.

 

Grace and peace,

Ben

[4krow 7,165]

Welcome Ben,

 

 Always good to hear a story like that. 

 

 What might help is for you to pop the top and show some good photos. That isn't automatically part of troubleshooting, but you are going to be headed there any way. I can't be certain, but we have a fairly extensive set of service manuals at this site and so that is a good place to start. You will meet some folks here that know a thing or two about this gear.

[3M_Audio 2,226]

Welcome Ben. The DH-500 is a very nice performing/sounding amp and if it were mine, I would definitely consider it worth repairing.

 

And as @4krow pointed out, we have the service manual for the HR-772 here (up under the 'Manuals and Specsheets' pull-down at the top of the page), so worth downloading and reading through - particularly the references to the protection circuitry which will shut down the receiver in certain out-of-bounds conditions. It may give you a sense of what sort of repair effort might be required and if you feel comfortable getting into it. If not, there are a couple of good Carver repair sources available referenced throughout the forums. 

 

And a search here may also give you some good info from others servicing the HR-772.

[Cring08 272]

Welcome!

[Dennis47 998]

WELCOME @Benjaminsswanson!

Glad you found us.

Good luck on your equipment repair projects.

[AndrewJohn 10,700]

Welcome @Benjaminsswanson, glad you found us.  Post some pics with the cover off, as @4k, suggested.  Someone may see something.

[Receiver2000 4,359]

Welcome and good luck on the repair.

[Kurt 3,108]

Welcome to the Carver Site!  Hope you post pics of your gear and repair process!

[Rob 6,205]

Welcome to the site.

[Benjaminsswanson 11]

Thank you all for the quick responses. I hope to open it up this weekend.

[2chGearBuff 437]

Welcome to the site!  Although it wasn't the HR-772 that lead me down the rabbit hole which ended up here, it was the first piece I ever bought.  Used it for a while, then it had some troubles.  Marriage, a couple of kids, decided to get it fixed at a local shop.  Then it all started!  Now I have four Carver systems in my house, well a mix of Carver and Sunfire gear!  My son currently has my HR-772 while he is living away while going to college!  Stll a power house of a receiver.  Remote quit several years ago, but not really into remotes anyway, so not worth trying to rememdy (universal  remote may work, but felt it wasn't a need on my behalf!)

 

Enyoy the ride and the people you meet here during your audio journey!

[Butcher 744]

On 2/3/2024 at 9:59 PM, Benjaminsswanson said:

Hi,

 

My dad bought some Carver stuff back when I was about 10 years old and now I have some of it in my living room as a 43 year old. I am currently utilizing the HR772 and 90% of the time it is working great. Occasionally though, it will turn off a few seconds after powering up. I have it powering some Hafler Model 400 towers. I also have a Hafler DH 500 but it is giving me some trouble ... the DH 500 needs some work.

 

Greeting Ben, and welcome to the site. 

 

Hafler amplifiers are robust and relatively simple designs, but the work was completed with passive components that were rather, shall we say... economically chosen. I've redone my share of them and had excellent results for reasonable amount of effort and cost. Whilst you've established that your Hafler 500 has been a spot of bother for you, you've not said what that bother is. Could you please elaborate?

[kve777 6,896]

Welcome, Ben!  I hope we can help you get your gear back to proper operating condition.  Does the HR-722 fail the same way using the Remote as the power button? Maybe you don't have the remote. It could be the power switch. If Dad had the Hafler 500 plugged into the switched AC socket, the extra draw could have caused contact damage to the switch. If it's acting up using the remote, it could be the contacts in the relay on the power switch board. Also aging Power Supply Filter Capacitors could be causing it to go into protection when first trying to power it on. That's where I'd start. BTW- you will need a decent DVOM for working on these. Please be careful. The filter caps can hold a nasty charge, even unplugged. Don't try to work on the power supply switch area with the unit plugged in. Let us know what you find. Good luck!

Edited February 10, 2024 by kve777

[JohnsonVintageRepairs 8]

Hi All,

 

I serviced the Carver HR-772 with a very similar issue and may have a fix. An intermittent problem from the client was that it would power on and then power itself off after 3-4 seconds. After chasing a few rabbits, it turned out to be dirty contact switch of the "stand-by" push button. By squirting some deoxit in the crevice and actuating the switch, the Carver no longer has the issue. Had to remove the front panel to get to it properly. 

 

~Ryan J

[JohnsonVintageRepairs 8]

Hi All -

 

Well... my fix above was temporary at best, it worked for a few hours. This intermittent issue of the display turning off after 3 seconds after powerup was fixed by the following:

 

1. Check 12V power rail to the FM Tuner board. 2. Check that clock from IC LM7001 is being generated and sent to main controller IC chip TMP47C870N. The main IC shuts down after 3 seconds if clock is not present. 

 

In my case, Q944 transistor was not providing sufficient voltage to FM Tuner board. Replaced original Q944 (2SD1682) with NTE 2684.

 

~Ryan J

 

[Benjaminsswanson 11]

Thank you all for the warm welcomes and I apologize for the extended delay. The Carver began working again for a number of months. I opened up the Hafler DH-500 and could see one of the terminals (I do not remember if it was RCA in or Speaker out) had turned far enough for one of the posts to be touching another terminal or the case. It now has been working very well. Occasionally I will have to adjust the RCA in as a channel will cut out. Once I have some spare time, I will open it back up and see if I can tighten up the jacks or may need to replace them (any recommendations on replacement RCA terminals is welcomed). I was able to pick up a Hafler DH-110 preamp a couple of months back for a good price locally, so I have my Technics SL 1700 playing and picked up a second hand Apple Airport Express A1392 to use a decent streamer. 

 

I briefly opened up the Carver and will post a few photos. There are no signs of leaking caps but I do see one of the larger caps has some deformation on the top. I'm out of town for the holidays but will have to take look at the repair manual and get my multimeter out when I get home to check out Ryan's findings. 

[4krow 7,165]

 Those bulging caps look to be a warning shot to me. But if you go into this piece, it will benefit you to replace more than just these. Looks like someone already replaced the big caps, so that makes me wonder too.

 Now, it depends on what you are willing to do as far as the RCA jacks. Many of us here have replaced them something more sturdy. Personally, I use the RCA jacks from Manley Labs, but they can require enlarging the RCA jack holes to fit. Maybe not though. Anyway, it sounds like the jacks were already replaced, as they were able to be twisted? The jacks that Carver uses can't be twisted since they are connected directly to the circuit board. Properly tightened jack replacements won't easily twist either, but it sounds like yours weren't.

 

 Correction. I just viewed the photos, and it looks like these ARE original RCA jacks. What that means to me is that the jack lost connection right at the solder joint on the board, and that should inspected. If twisting the cable makes it work again, that is the problem.

Edited December 20, 2025 by 4krow
added info

[Benjaminsswanson 11]

3 hours ago, 4krow said:

 Those bulging caps look to be a warning shot to me. But if you go into this piece, it will benefit you to replace more than just these. Looks like someone already replaced the big caps, so that makes me wonder too.

 Now, it depends on what you are willing to do as far as the RCA jacks. Many of us here have replaced them something more sturdy. Personally, I use the RCA jacks from Manley Labs, but they can require enlarging the RCA jack holes to fit. Maybe not though. Anyway, it sounds like the jacks were already replaced, as they were able to be twisted? The jacks that Carver uses can't be twisted since they are connected directly to the circuit board. Properly tightened jack replacements won't easily twist either, but it sounds like yours weren't.

 

 Correction. I just viewed the photos, and it looks like these ARE original RCA jacks. What that means to me is that the jack lost connection right at the solder joint on the board, and that should inspected. If twisting the cable makes it work again, that is the problem.

Sorry, the RCA issue is on the Hafler 500 amplifier. I was responding to a couple things. All the photos are of the Carver. I believe my dad got the Carver new and never had it in the shop, so I am pretty confident it is all original. The problem with the Carver is it going into protection mode after a few seconds (except when it doesn't and works fine for a few months). 

[HoraceAnkle 10]

Welcome !