My dad gifted me his Adcom system and I cannot get it to produce sound

F

faktory4

Audiophyte
My dad has had an Adcom system since the early 90s. I've lusted after it since he got it and the other day he asked if I wanted it (I of course immediately said yes).

He gave me a:

GFP-555
GFA-545
GFA-535

Am I correct that the 545 and 535 are both amps, and only one is necessary? I have no idea why he had two of them and neither does he. He was not an audio enthusiast but wanted a nice system at some point and isn't familiar with the connections.

When I brought the system home I was foolish enough to disconnect everything and now I can't get it to produce sound. My dad said he used it within the last five years or so.

I am attaching two photos - one showing the rear of the system, and one showing the front.

From the Video/Aux port, I have an RCA cable connected to the headphone jack of a laptop. The laptop has "Stereo Speakers" as the output type. I also tried connecting it to my phone to no luck.

The Main Out of the 555 (lab port) is connected to the Input of the 545. I only have one speaker connected in the photos for testing purposes. (the cheap speaker cable is just temporary for testing). I also tried the "norm" port as well to no luck.

I also tried plugging in some headphones into the headphone port but I still didn't hear anything.

Any idea what I'm doing wrong (if anything)?

Also, if I can get it to work, how can I connect a subwoofer to this system?

My local repair shops charge $125 just to look at something, so I am trying to avoid that.

I have not yet tried the 535 and the 555 because I don't have thick enough speaker wire to use the terminals on the amp.

In in Fairfax, VA if anyone local can look at it in person.
 

Attachments

Last edited:
everettT

everettT

Audioholic Spartan
Do you have something other then your laptop you can check, phone or cd?
 
adk highlander

adk highlander

pessimistic optimist
Do you see the light for each channel change color? Do year the relays click? Did you try both amps?
 
TLS Guy

TLS Guy

Seriously, I have no life.
My dad has had an Adcom system since the early 90s. I've lusted after it since he got it and the other day he asked if I wanted it (I of course immediately said yes).

He gave me a:

GFP-555
GFA-545
GFA-535

Am I correct that the 545 and 535 are both amps, and only one is necessary? I have no idea why he had two of them and neither does he. He was not an audio enthusiast but wanted a nice system at some point and isn't familiar with the connections.

When I brought the system home I was foolish enough to disconnect everything and now I can't get it to produce sound. My dad said he used it within the last five years or so.

I am attaching two photos - one showing the rear of the system, and one showing the front.

From the Video/Aux port, I have an RCA cable connected to the headphone jack of a laptop. The laptop has "Stereo Speakers" as the output type. I also tried connecting it to my phone to no luck.

The Main Out of the 555 (lab port) is connected to the Input of the 545. I only have one speaker connected in the photos for testing purposes. (the cheap speaker cable is just temporary for testing). I also tried the "norm" port as well to no luck.

I also tried plugging in some headphones into the headphone port but I still didn't hear anything.

Any idea what I'm doing wrong (if anything)?

Also, if I can get it to work, how can I connect a subwoofer to this system?

My local repair shops charge $125 just to look at something, so I am trying to avoid that.

I have not yet tried the 535 and the 555 because I don't have thick enough speaker wire to use the terminals on the amp.

In in Fairfax, VA if anyone local can look at it in person.
You have connected it correctly. You need to try another source. If that does not work, then one of the units is not working. If you can't hear anything from the headphone jack, that suggests that the preamp is not working.

I have researched this and find that the power supplies of those 555 preamp units are somewhat trouble prone. If the on light comes on, but you do not hear the relay click, then the power supply has failed.

Since you are not experienced in repair, you will have to find someone to service it. On DIY sites there are modifications suggested for the power supply.
 
Last edited:
P

PENG

Audioholic Slumlord
My dad has had an Adcom system since the early 90s. I've lusted after it since he got it and the other day he asked if I wanted it (I of course immediately said yes).

He gave me a:

GFP-555
GFA-545
GFA-535

Am I correct that the 545 and 535 are both amps, and only one is necessary? I have no idea why he had two of them and neither does he. He was not an audio enthusiast but wanted a nice system at some point and isn't familiar with the connections.
Yes, the 545 and 535 are both power amps, you can use either one.

I am attaching two photos - one showing the rear of the system, and one showing the front.

From the Video/Aux port, I have an RCA cable connected to the headphone jack of a laptop. The laptop has "Stereo Speakers" as the output type. I also tried connecting it to my phone to no luck.
Your photo shows you have selected the phono input, you should select the Video/Aux input, otherwise you will have no sound, because your laptop is connected to the Video/Aux input.

The Main Out of the 555 (lab port) is connected to the Input of the 545. I only have one speaker connected in the photos for testing purposes. (the cheap speaker cable is just temporary for testing). I also tried the "norm" port as well to no luck.
For you, at least in the beginning, use the NORM output, it is safer to use than the LAB output.

I also tried plugging in some headphones into the headphone port but I still didn't hear anything.
Again, make sure you have the GFP input selected to Video/Aux.

Any idea what I'm doing wrong (if anything)?
Too early to tell, my guess is, maybe something is not right about the way you setup the laptop or you have a bad cable.

Are you using one like the following:
1693480312892.png


Also, if I can get it to work, how can I connect a subwoofer to this system?
Yes you can, just use a y-splitter with the regular left/right outputs.

I have not yet tried the 535 and the 555 because I don't have thick enough speaker wire to use the terminals on the amp.
But your attached photo shows you have the GFP555 hooked up, so what do you mean by have not tried it yet?
 
TLS Guy

TLS Guy

Seriously, I have no life.
Yes, the 545 and 535 are both power amps, you can use either one.



Your photo shows you have selected the phono input, you should select the Video/Aux input, otherwise you will have no sound, because your laptop is connected to the Video/Aux input.



For you, at least in the beginning, use the NORM output, it is safer to use than the LAB output.



Again, make sure you have the GFP input selected to Video/Aux.



Too early to tell, my guess is, maybe something is not right about the way you setup the laptop or you have a bad cable.

Are you using one like the following:
View attachment 63104



Yes you can, just use a y-splitter with the regular left/right outputs.



But your attached photo shows you have the GFP555 hooked up, so what do you mean by have not tried it yet?
He has NOT selected the phono input. You are looking at the record out control. The "listening" control is clearly set to video/aux.

I see no reason why this unit should not be outputting sound, except for a fault. Anyhow my researches show, that if there in no relay click, then the power supply has failed, which I understand is a known issue on these units. So that will decide the issue. No click after turn on, then the power supply needs service.
 
F

faktory4

Audiophyte
Thank you all for the replies. I had to be away from my computer for a while yesterday after making the post.

This morning I managed to find thick enough speaker cable to test the 535 and it works. So between the 555 and the 535 I can produce sound.

It's just the big 545 unit that does not work.

Would the 545 be a big enough increase to justify getting it fixed? My speaker setup is modest in comparison to these components - I have a set of Energy CB-20 bookshelf speakers. I don't have any immediate plans to upgrade the speakers. It would be $125 just to get a shop to look at the amp, and then whatever a power supply fix would be (assuming that is indeed the issue).

Regarding the reply about the subwoofer:

Also, if I can get it to work, how can I connect a subwoofer to this system? Yes you can, just use a y-splitter with the regular left/right outputs.

Where on the back of the pre-amp do I plug in the sub? There's no specific line-out for a subwoofer.
 
Last edited:
TLS Guy

TLS Guy

Seriously, I have no life.
Thank you all for the replies. I had to be away from my computer for a while yesterday after making the post.

This morning I managed to find thick enough speaker cable to test the 535 and it works. So between the 555 and the 535 I can produce sound.

It's just the big 545 unit that does not work.

Would the 545 be a big enough increase to justify getting it fixed?

My speaker setup is modest in comparison to these components - I have a set of Energy CB-20 bookshelf speakers.

Regarding the reply about the subwoofer:

Also, if I can get it to work, how can I connect a subwoofer to this system? Yes you can, just use a y-splitter with the regular left/right outputs.

Where on the back of the amp do I plug in the sub? There's no specific line-out for a subwoofer.
Well, we now know which is the dead unit. The 545 is 100 watts per channel and the 535 is 60 watts per channel. So it all depends on how loud you want to play it. Although that is 40 watts increase in power per channel, that is a little less than 3db increase in spl. So enough to notice but not huge. Since it is a decent unit, i would encourage fixing it.

As far as a sub, you have no bass management, so you will not be able to limit the bass to your main speakers, but you can use a sub to increase bass extension. You just need a couple of Y-connectors. The single ends go to your preamp, and one of each pair of double ends goes to the power amp and the other to the sub. Then you set the sub crossover and volume level.

What are your speakers? Generally when doing this, a good starting point to set the crossover is the F3 of the speakers plus 50%.
 
F

faktory4

Audiophyte
Well, we now know which is the dead unit. The 545 is 100 watts per channel and the 535 is 60 watts per channel. So it all depends on how loud you want to play it. Although that is 40 watts increase in power per channel, that is a little less than 3db increase in spl. So enough to notice but not huge. Since it is a decent unit, i would encourage fixing it.

As far as a sub, you have no bass management, so you will not be able to limit the bass to your main speakers, but you can use a sub to increase bass extension. You just need a couple of Y-connectors. The single ends go to your preamp, and one of each pair of double ends goes to the power amp and the other to the sub. Then you set the sub crossover and volume level.

What are your speakers? Generally when doing this, a good starting point to set the crossover is the F3 of the speakers plus 50%.
Thank you - my speakers are budget in comparison - they are Energy CB-20 bookshelf speakers.

I'm sorry to be dense, but I'm still unclear on the sub hookup. I understand I can't cut out bass to the bookshelf speakers, but I don't know where the plugs would go. My sub is an Infinity R12. It is currently hooked up to my Yamaha receiver with a single cable from the sub to the sub-out port on the receiver.
 
TLS Guy

TLS Guy

Seriously, I have no life.
Thank you - my speakers are budget in comparison - they are Energy CB-20 bookshelf speakers.

I'm sorry to be dense, but I'm still unclear on the sub hookup. I understand I can't cut out bass to the bookshelf speakers, but I don't know where the plugs would go. My sub is an Infinity R12. It is currently hooked up to my Yamaha receiver with a single cable from the sub to the sub-out port on the receiver.
Your sub has right and left line inputs. So you connect one end of the left Y-connector to the left input on the sub and one end of the right Y-connector to the right input on your sub. The sub will have a buffer circuit so it does not common the left and right channels of you preamp, but will combine them for the sub.

I think you are due for a speaker upgrade all the way round, to get the best from that gear.
 
highfigh

highfigh

Seriously, I have no life.
Thank you all for the replies. I had to be away from my computer for a while yesterday after making the post.

This morning I managed to find thick enough speaker cable to test the 535 and it works. So between the 555 and the 535 I can produce sound.

It's just the big 545 unit that does not work.

Would the 545 be a big enough increase to justify getting it fixed? My speaker setup is modest in comparison to these components - I have a set of Energy CB-20 bookshelf speakers. I don't have any immediate plans to upgrade the speakers. It would be $125 just to get a shop to look at the amp, and then whatever a power supply fix would be (assuming that is indeed the issue).
The problem has nothing to do with the thickness of the speaker wire. This would work if the wire was very thin.

The 545 has at least one fuse holder n the rear- unplug the power cord and check the fuse (replace it if it failed). Once the fuse has been checked/replaced, plug in the amplifier's power cord and without touching anything else, press the power button. Do this without speakers connected. If the fuse doesn't fail, shut it off and connect the speakers- press the power button and if it doesn't fail, shut it off and connect a source. If it works, you may not have to take it in. However, it wouldn't be a bad idea to take it in for a checkup- be careful about your choice- service shops are a dying breed and many people make claims they can't back up.
 
davidscott

davidscott

Audioholic Ninja
Wow that is some nice vintage gear. Good luck getting it working right. :)
 
P

PENG

Audioholic Slumlord
Thank you all for the replies. I had to be away from my computer for a while yesterday after making the post.

This morning I managed to find thick enough speaker cable to test the 535 and it works. So between the 555 and the 535 I can produce sound.

It's just the big 545 unit that does not work.

Would the 545 be a big enough increase to justify getting it fixed? My speaker setup is modest in comparison to these components - I have a set of Energy CB-20 bookshelf speakers. I don't have any immediate plans to upgrade the speakers. It would be $125 just to get a shop to look at the amp, and then whatever a power supply fix would be (assuming that is indeed the issue).

Regarding the reply about the subwoofer:

Also, if I can get it to work, how can I connect a subwoofer to this system? Yes you can, just use a y-splitter with the regular left/right outputs.

Where on the back of the pre-amp do I plug in the sub? There's no specific line-out for a subwoofer.
As suggested, check the fuse. If it is blown and not due to a fault, then it is a quick fix. The 545 is a decent power amp. The 535 is weak for a power amp, it has a small power supply, it is not bad for speakers with good sensitivity, and in that case you can count on its generous headroom.
 
F

faktory4

Audiophyte
I got the 555 and 535 paired up, working, and integrated into my meager 2.1 setup.

There's a very noticeable difference in sound compared to my old basic Yamaha receiver I replaced.

As to the other amp - for now it will hang out in storage until I decide what to do. I doubt my current speakers are nice enough to justify the repair cost. I'll invest in some nicer speakers down the road and then I'll get the 545 fixed.

Thanks for all the help!
 
BMXTRIX

BMXTRIX

Audioholic Warlord
I got the 555 and 535 paired up, working, and integrated into my meager 2.1 setup.

There's a very noticeable difference in sound compared to my old basic Yamaha receiver I replaced.

As to the other amp - for now it will hang out in storage until I decide what to do. I doubt my current speakers are nice enough to justify the repair cost. I'll invest in some nicer speakers down the road and then I'll get the 545 fixed.

Thanks for all the help!
What issue did you find you were running into? Might be helpful to others who are running into a similar problem in the future. Even if you just did something dumb, that can be the worst kind of problem to have to try and fix.
 
lovinthehd

lovinthehd

Audioholic Jedi
Just for kicks, do you have the manuals? Long ago I lost the manual for my 30ish year old ADCOM GTP-500 preamp but in just the last year or so I was able to find a PDF of it on the internet.

Here is the GFP-555 manual
A great source for manuals, often including service manuals and other literature, is hifiengine.com https://www.hifiengine.com/manual_library/adcom/gfp-555.shtml
 
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