20 Most Recent Adcom GFA-5802 2-Channel Amplifier Questions & Answers

Remove the output transistors and measure each of the sets of 3 pads and report the voltage readings here. I suspect that you have either a blown driver circuit or output transistors. The voltage readings will give me an idea on where to start looking for specifics.

Thanks,
Dan

Possibly. Most amps filter out line hum via low-pass filters. If you can locate a schematic, those would be the caps to check.

It should run hot to touch at idle, about 120F, because it is MOSFET type amplifier.

Sounds like it could be feedback hum. Is there anything near it that could cause a reaction when unpluged? Such as a turntable, cassette etc. If so move them and see if it goes away. Even then it won't hurt the amp. I think otherwise worry when there's a hum when they are plugged in. PS check any earth connections too!

Hi Allister...

Check for fuses and make sure that the speakers are solidly connected at both ends

I can suggest a repair place if needed

Flip Window Relay Fuse 29 Fog Lamp Relay Fuse 9 Fuel Pump Relay Fuse 19 Headlamp Relay Fuse 8 Heated Grid Relay Fuse 27 Horn Relay Fuse 5 Engine Fuse Module (Fuse 1) Fuse 24 Engine Fuse Module (Fuse 2) Fuse 16 Engine Fuse Module (Fuse 3) Fuse 6 Engine Fuse Module (Fuse 5) Fuse 6 This will help. Thanks please keep updated. please do rate the solution positively .thank you for using fixya.

Have it serviced. Do you know what GFA stands for. People at Adcom do have a great sense of humor. Take it only to a high end audio servicer. Contact Adcom. This is good stuff you wouldn't want a hack working on it.

Running an amp in bridge mode requires a specific circuit design. It is not possible to combine 2 amps in this fashion.
Dan

It sounds as if there is a broken solder joint somewhere that slowly opens up with heat. The other possibility is that an input or driver transistor is dying. Since the whole channel is dying, I would guess the broken joint and/or dying transistor are near the very input of the channel.
A tech can very easily find the spot by playing the amp until it starts to die, then spraying small bursts of freeze spray, one component or area at a time, until the amp suddenly comes back to life.
 

If your Adcom GTP-450 preamp is only working through an external processor, there could be several potential reasons for this issue. Here are some troubleshooting steps you can take to try to identify and resolve the issue:

1. Check Input Selection: Ensure that you have selected the correct input source on the preamp. Sometimes, if the incorrect input is selected, it may seem like the preamp is not working.
2. Inspect Cables and Connections:
   • Make sure that all cables (audio, video, power) are securely connected to both the preamp and the external processor.
   • Check for any loose or damaged cables. If you find any, replace them.
3. Verify the External Processor's Settings:
   • If you are using an external processor, ensure that it is set up correctly and functioning properly. Check its input and output settings.
4. Check for Mute or Volume Levels:
   • Verify that the preamp's volume is not set to zero or muted. Also, check the volume settings on the external processor.
5. Test Different Inputs and Outputs:
   • Try using different input and output connections on both the preamp and the external processor to see if there is any change in behavior.
6. Reset to Factory Defaults:
   • Consult the user manual to see if there is a way to perform a factory reset on the preamp. This can sometimes resolve software or configuration-related issues.
7. Firmware or Software Update:
   • Check if there are any available firmware or software updates for the Adcom GTP-450 preamp. Updating the firmware/software can sometimes address compatibility or performance issues.
8. Consult the User Manual or Manufacturer's Support:
   • Review the user manual for troubleshooting tips specific to your model. If the issue persists, consider reaching out to Adcom's customer support for further assistance.
9. Consider Professional Repair:
   • If none of the above steps resolve the issue, it may be a hardware problem. In this case, consider seeking help from a qualified audio technician or contacting Adcom for repair options.

Please be cautious when performing any troubleshooting steps, especially if they involve opening or modifying electronic equipment. If you're unsure about any step, it's best to seek professional advice to avoid potential damage.

There are several things that could be causing the lack of sound output from your Adcom GFP 710. Here are a few things to check:

1. Check the cables: Make sure that the cables connecting the preamp to the power amp and speakers are securely plugged in and in good condition.
2. Check the input selection: Make sure that the correct input is selected on the preamp.
3. Check the volume: Make sure that the volume is turned up and not muted.
4. Check the balance: Make sure that the balance is set correctly and not all the way to one side.
5. Check the output jacks: Make sure that the output jacks on the preamp are functioning properly.
6. Check the power supply: Make sure that the power supply is providing the correct voltage to the preamp.

If none of these solutions work, it is possible that there is an issue with the preamp itself. It may need to be serviced or repaired by a qualified technician.

Thanks for your suggestions. However I am using carefully boxed clean CDs and the skipping is on all. The Laser glass is clean. Since submitting the problem I removed case and the CD is lifted off tray by a lift motor which has a round nylon top on the shaft which "sandwiches" the CD against a freely rotating plastic piece in a lipped cylinder container. The lift motor then rotates the CD which is read by a separate fixed laser. My current suspicion is that the CD is slipping inside the rotating "sandwich". Hopefully someone who has worked on an Adcom GCD 600 can suggest a fix.

Back in the late 1980's the GCD-575 was about as good as you could get in CD players. Today it likely can still hold its own when rejuvenated to original operating condition when it left the factory (but can't play SACD's hires layer). Main problem... deteriorated main board soldering, a few hours with a solder sucker, (best to resolder use 2% or 4% silver solder everywhere) and replace 32 year old caps, and this set should equal the sound of a mega-buck player (also change the open/close belt). Modern caps are likely smaller so a 2,200 can be replaced by a 3,300 or 4,700 uF. part at the same voltage, etc. the output cap value should be doubled, and a bipolar used, or bypassed with a polypropylene or Teflon, IIRC plenty of room is available inside the case for either (or both). That is a lot of work. Well worth it. -Steven

https://www.diyaudio.com/forums/solid-state/236765-adcom-gfa-555-ii-blowing-main-line-fuse-ideas.html

Hello Curtis, comment that teams accompany the Adcom, to know where the signal arrives at the entrances of the GFA6000, I ask you this, to make a map of your sound system and try to find the possible place of failure Try the left and right speakers, in the outputs that work, it can be the Surround, to check that they are working I await your comment Greetings Franco Dosil Hola Curtis, comenta que equipos acompa?an al Adcom, para saber de donde llega la se?al a las entradas del GFA6000, te pido esto, para hacer un mapa de tu sistema de sonido y tratar de encontrar el posible lugar de falla Prueba los parlantes izquierdo y derecho, en las salidas que funcionen, puede ser las de Surround, para comprobar que est?n funcionando Espero tu comentario Saludos Franco Dosil