A Real Barn Find - Marantz 2325 with a Puzzle

Yes more pics please .... check the condition of the relay and also verify PS voltages. I acquired one with a blown power amp AND one side of the relay contacts were burnt.
Thanks, I will get more as I go. And yes, the voltages on the PS all look good. Relay is new. Still digging in...
 
Scott,

This is a good time to download the 2325 service manual. It contains a short section on adjusting the power supply. You can find it several places including here:
hfiengine.com.

Check out section 20 on page 11 of the service manual for instructions on where to test the power supply output and how to adjust it.
Thanks Randy - I'm back from 3 days at work and I had a look and adjusted everything to spec. right channel is still dead quiet. PS voltages all good too. Something disconnected maybe? Two of the big output transistors had red X's on them and tested shorted when I got this thing. Are there other components that could have been taken out when that first occurred? Should I check all resistors or some other transistors? Or would those components not take a channel out so completely? The right channel is absolutely gone.
 
I am not an electronics expert at all. Can't do crap. But I was wondering if your item had pre-jumpers? Are they in place? Just a guess.
I can't do crap either, but I'm learning good crap! No, this one has 'jumpers' internally. But missing stuff like that would be my speed.
 
There was no mention of it in a previous post, but do you have a DBT? If so, it'd be a good idea to use it and find out if you have a short somewhere and it'll help prevent the issue from cascading. Your dead channel can be a variety of things, but those red X's on the output transistors might be a clue. Sounds like maybe someone couldn't afford the repairs so they dumped it. Your score! :thumbsup:
Thanks! I'll make a DBT and start using tomorrow. I'll keep everyone posted...
 
There was no mention of it in a previous post, but do you have a DBT? If so, it'd be a good idea to use it and find out if you have a short somewhere and it'll help prevent the issue from cascading. Your dead channel can be a variety of things, but those red X's on the output transistors might be a clue. Sounds like maybe someone couldn't afford the repairs so they dumped it. Your score! :thumbsup:
Well, made simple dim bulb tester, and plugged the 2325 into it (after verifying the DBT worked with another device). There is a problem: the bulb went full brightness instantly and then after about 3 seconds it goes into a steady low glow. I turned it off and repeated again with the same results.
Now I know why my basement lights blinked every time I turned the 2325 on! I don't understand why it changes from bright to soft, however. Isn't a short a short?
I'm going to pull the PS board and have a physical look but not sure what to check with the DVM. Any ideas out there?
 
That is the way a DBT is supposed to work. It is bright for a few seconds as those big caps charge up (high current flow), and then it dims as the current flow decreases. If there is a short, the current stays high and the bulb stays bright. If it's bright after 8-10 seconds, time to turn it off and go looking for the problem. If yours dims, that is good news.
 
What wattage bulb are you using in your dim bulb? For a high power amp like that you need a minimum of 150 watt bulb I normally use a 200 Watt on really high power amps.

If it goes to dim that's the main caps charging up not a problem. Where both transistors marked with an X on the same amp board? If so you need to check all the transistors on the driver board.

You will probably need a signal tracer of some sort from this point on. You can make one with a set of earbuds. Just cut the end off and strip the wires back, connect an alligator clip with about 6 inches of wire to the ground wire, and connect the two signal wires together with a probe. Connect the alligator clip to ground and you can use the probe to trace the signals through the amp be careful not to short anything. When I am using a probe I connect the unit to my Dim bulb tester. this give a little bit of assurance that if you slip you won't blow everything up.

I have found that the tone boards and tone switches can cause this problem. For simplest testing use AUX or TAPE inputs These inputs connect directly (through switches) to the Balance control, then Volume control, then tone board, then filter switches.
Good Luck.
 
That is the way a DBT is supposed to work. It is bright for a few seconds as those big caps charge up (high current flow), and then it dims as the current flow decreases. If there is a short, the current stays high and the bulb stays bright. If it's bright after 8-10 seconds, time to turn it off and go looking for the problem. If yours dims, that is good news.
I didn't think of those filter caps charging up - that's good news. Thanks, Steven!
 
What wattage bulb are you using in your dim bulb? For a high power amp like that you need a minimum of 150 watt bulb I normally use a 200 Watt on really high power amps.

If it goes to dim that's the main caps charging up not a problem. Where both transistors marked with an X on the same amp board? If so you need to check all the transistors on the driver board.

You will probably need a signal tracer of some sort from this point on. You can make one with a set of earbuds. Just cut the end off and strip the wires back, connect an alligator clip with about 6 inches of wire to the ground wire, and connect the two signal wires together with a probe. Connect the alligator clip to ground and you can use the probe to trace the signals through the amp be careful not to short anything. When I am using a probe I connect the unit to my Dim bulb tester. this give a little bit of assurance that if you slip you won't blow everything up.

I have found that the tone boards and tone switches can cause this problem. For simplest testing use AUX or TAPE inputs These inputs connect directly (through switches) to the Balance control, then Volume control, then tone board, then filter switches.
Good Luck.
Thanks for the help!
I only have a 75W bulb here - ramifications of using that? Burn out the bulb,I would guess.
Those bad output transistors were on the same board. Unfortunately, I didn't keep track of which board they were on - I was so sure new transistors and caps were going to bring everything back to life - troubleshooting error #1 of many.
Not sure I have the experience to trace signals through. Do you mean connecting a CD player to Aux and then listening to points throughout the unit? Wouldn't know where to begin, and looking at the schematic (which doesn't fit together all that well from page to page as found on HiFi Engine) I could only identify a few partial signal paths at best. I'd do better with a list of test points.
Oh, and BTW, I can use a CD player in Main In and get both channels just fine. Problem precedes that. Back to controls and Tone Board?
 
The 75W bulb will glow at idle, and probably light up with very little load applied to the amplifiers. I use a 100W which works fine with the 2325, there is just a dim glow at idle. As suggested above, a 150W would be nice, but we can't even purchase the 100W incandescent lamps any more.
 
The 75W bulb will glow at idle, and probably light up with very little load applied to the amplifiers. I use a 100W which works fine with the 2325, there is just a dim glow at idle. As suggested above, a 150W would be nice, but we can't even purchase the 100W incandescent lamps any more.
Go to a true value, or any mom and pop hardware store I just bought a 150, 200, and 300 at Ganal lumber. I use the 300 for Sansui BA 5000, and Marantz 500s.
 
The 75W bulb will glow at idle, and probably light up with very little load applied to the amplifiers. I use a 100W which works fine with the 2325, there is just a dim glow at idle. As suggested above, a 150W would be nice, but we can't even purchase the 100W incandescent lamps any more.
Thanks, Randy. I was wondering what size bulb to use on the 2325. I'll talk to you later today.
 
If you can’t trace signals, I will put a thing together tomorrow and post.
Great! I really wish I knew how to step through a signal path somehow. Any clues you can provide will be put to use - I'm really determined to get this thing operating properly.
 
About those bulbs.....we still have to use old-style incandescent bulbs for a Dim Bulb tester, right?
 
About those bulbs.....we still have to use old-style incandescent bulbs for a Dim Bulb tester, right?
Yes. This was discussed somewhere before. LED's and fluorescents don't present the resistance that incandescents do, and that resistance is critical.
 
Yes. This was discussed somewhere before. LED's and fluorescents don't present the resistance that incandescents do, and that resistance is critical.
Got some 100W, 150W and 200W bulbs at Walmart. There weren't many left. Time to get some for your DBT's !
(really bugs me that the incandescents are being eliminated - and notice that word is questioned by your spell checker as if it doesn't exist. WTH?)
 
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