9090

Willy6

Willy6

AK Subscriber
Subscriber
I ran into a great deal on another 9090 today and couldn't pass it up so I got it home put it on the DBT and the 150 watt light bulb went out and the relay clicked and it powered up so then I hooked up a pair of old test speakers thinking everything was good but nope I'm getting sound through both channels but they are both very quiet with the volume turned all the way up it is as if it was only turned up to 1 on the dial.
 
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Check to see if the jumper plugs in the back are missing The pre out-- main in jumpers. verify also that the tape monitor switches aren't pusged in or the audio mute button
 
Tom B said:
Check to see if the jumper plugs in the back are missing The pre out-- main in jumpers. verify also that the tape monitor switches aren't pusged in or the audio mute button
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The jumpers are in.I narrowed it down to the power amp section I hooked it up as a preamp to my 919s power amp and everything worked fine then I used my 919 as a preamp and found the same symptoms.
 
Make sure the tape monitor is set correctly. Also, try other positions of the rotatory switches. The knobs may not be indexed correctly.

- Pete
 
So you probably need a new relay, but the contact welded could be caused by a bad amplifier (outputs). Are they welded together on the normally closed side, or the normally open side (Normally open contacts are the movable contact as well as the contact it touches when the relay energizes)
Mouser sells a relay like that (MY3-02-DC24). To see if you have an output issue check the contacts that come from the amplifier to the protect relay. the easiest way is to measure the voltage on pin 3 and pin 4 of the protect board (where the relay is mounted)
 
Tom B said:
So you probably need a new relay, but the contact welded could be caused by a bad amplifier (outputs). Are they welded together on the normally closed side, or the normally open side (Normally open contacts are the movable contact as well as the contact it touches when the relay energizes)
Mouser sells a relay like that (MY3-02-DC24). To see if you have an output issue check the contacts that come from the amplifier to the protect relay. the easiest way is to measure the voltage on pin 3 and pin 4 of the protect board (where the relay is mounted)
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It is welded together at the normally closed spot and with the relay removed I'm getting around 34mv at the pin 4 hole and 3.4mv at the pin 3 hole.
 
You may have had a short in the power amp. That NC contact that the wiper welded to is supposed to be ground connection to dissapate the power so that DC doesn't develop on the speakers after you shut down. There may have been heavy DC, the trpe which appears when you lose part of an output stage.
I just looked at the service manual and schematic again. I am not sure if that unit uses a MY3-02-DC24 relay or a MY4-02-DC24 relay. The schematics shows a 3 contact set relay, and other 9090DB's use a 3 contact set relay, but the pictorial of the board shows a MY4-02-DC24 relay with 4 sets of contacts. @ sets are paralled together for 1 speaker, and the other set is single set for the other speaker, and the last set is for the red and green protect LED's.
If the wires going to the protect board on pin 3 and 4 are only measuring that small amount of millivolts, it doesnt appear there is an amp issue now. The only way to find out is replace the relay, or free the welded contact, clean and polish making sure the contacts are all making and breaking properly and try the unit out, without speakers connected first. see if the relat now engages properly, and measue the DC at the speaker terminals. If its still low you can try with headphones or speaker, I would just suggest you use a dim bulb tester.
 
does your unit use the MY3 relay, or MY4?? MY3 has 3 contact sets, and MY4 has 4 sets
 
Tom B said:
does your unit use the MY3 relay, or MY4?? MY3 has 3 contact sets, and MY4 has 4 sets
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The relay came and I installed it and now the right channel is working correctly but the left channel is still very quiet
 
Check all fuses and make sure they are ok. The 9090 also has fuses on the driver board as well as on the power supply board.
Check the relay connections and make sure the foil didn't break anywhere while you were removing or reinstalling the relay.
Exercise the tape monitor switches, mono/stereo, and speaker switches to make sure one is not spotty.
Check different functions such as AM, and FM and aux or phono input.

If you still can't get sound on the left, remove the 2 "U" shaped jumpers in the back. (Pre Out, Main In). Use a set of audio cables with RCA plugs at both ends similar to the ones you would use for connecting up a tape deck. They are color coded so you will know matches on both ends. Cross the cables so that the Left pre out goes to the Right Main in, and the Right pre out goes to the left main in. Turn on the unit. If the left is still out, you probably have a driver board or output transistor problem (expected due to the welded relay contacts). If the right channel is now inop, suspect a really dirty switch, or a tone amp/preamp problem like an open capacitor or bad transistor or BA312 IC.
 
Tom B said:
Check all fuses and make sure they are ok. The 9090 also has fuses on the driver board as well as on the power supply board.
Check the relay connections and make sure the foil didn't break anywhere while you were removing or reinstalling the relay.
Exercise the tape monitor switches, mono/stereo, and speaker switches to make sure one is not spotty.
Check different functions such as AM, and FM and aux or phono input.

If you still can't get sound on the left, remove the 2 "U" shaped jumpers in the back. (Pre Out, Main In). Use a set of audio cables with RCA plugs at both ends similar to the ones you would use for connecting up a tape deck. They are color coded so you will know matches on both ends. Cross the cables so that the Left pre out goes to the Right Main in, and the Right pre out goes to the left main in. Turn on the unit. If the left is still out, you probably have a driver board or output transistor problem (expected due to the welded relay contacts). If the right channel is now inop, suspect a really dirty switch, or a tone amp/preamp problem like an open capacitor or bad transistor or BA312 IC.
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Hey Tom thank you for the help sorry it took so long to get back to ya ( they're running Me ragged with overtime at work)I checked over everything on F-2543 & F-2544 accept the BA-312s because I wasn't sure on how to test them so I found some on eBay and ordered two needless to say I replaced the one on F-2543 and I now have both channels working properly after I got the problem fixed I went ahead and recapped all of the boards accept the tuner section and everything is working fine now.Thanks again.
 
Tom B said:
Glad it worked out
Tom
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I spoke to soon now I noticed that the front panel lights go out when I turn it to phono or aux the meters and the aux or phono light up but not the full blue tuner section I can't remember if that is normal or not?
 
Willy6 said:
I spoke to soon now I noticed that the front panel lights go out when I turn it to phono or aux the meters and the aux or phono light up but not the full blue tuner section I can't remember if that is normal or not?
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It is normal, and there is a mod about it.
 
Willy6 said:
Also i noticed someone on ebay is selling an upgrade kit for the BA-312 anyone have experience with this upgrade and is it worth the $100 they're asking for?
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Original it was a project between the guy of sparkos labs, and guy with (well deserved) bad reputation. Lately is just from sparkos labs. Some people say that they are noticeable upgrade on marantz 2275.
But who knows
 
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