JVC SEA-20 SEA Graphic EQ

fairlyodd45

New Member
Okay mates this is my first post and sorry if it isn't in the proper place, but not really sure where to post just yet. Okay here is the deal...I own a Vintage JVC SEA-20 EQ and the bloody thing will not power up although all of the inline fuses seem to be in proper condition due to my multimeter. Any suggestions as to what I should do next as far as testing her out would be greatly appreciated.

Thank you in advance !

Charlie \m/
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Have you used your meter to check and see if power is getting to the power transformer? And after that, check and see if there is any power coming from the secondary side of the power transformer.

If you have power through out the circuit, them maybe the power light bulb is just burned out?
 
Have you used your meter to check and see if power is getting to the power transformer? And after that, check and see if there is any power coming from the secondary side of the power transformer.

If you have power through out the circuit, them maybe the power light bulb is just burned out?

After further testing and a bit of eyeballing. I noticed that the 2 50V Caps on the power board were leaking, not bulged, but leaking from the bottom. There are at least six Caps in the entire unit that are leaking. 2 I already mentioned above ad at least 4 other lesser value Caps on the logic board itself. The sliders test out and the values are within tolerance, but I tested the power transformer and it failed low, which is a blessing actaully. I am gong to replace all the Caps with good quality Panasonics' and I may as well replace the VR's as well. I have a new power transformer with the same value, so I will be installing that as well. I would share photos, but alas my Android does not play well with OSX sadly..I will keep you all informed as to my progress, but I am seriously wondering why on earth all these components failed so miserably in such a nice unit. JVC was known for their quality products back in the day. What gives with this issue ? Any comments would be greatly appreciated.

Thanks again for all of your support and suggestions,

Cheers !
 
The "leaking" on the caps is probably assembly glue.

If you haven't owned the unit since new, who knows what its been through.
 
No power suggests bad power transformer, bad power switch, blown fuse, blown diodes, or all of the above.

Capacitors don't usually leak their fluids unless there is a catastrophic break down event or an over powering event such as a voltage surge which might lead to their heating up. Almost all capacitors I have seen in vintage SS equipment have been made from the factory with slit tops so that when they do vent, they do so from the top and you will see them split open.

People who see what looks like a wet look on their circuit boards, automatically assume that the cap has leaked over their boards and have not tested them with either a capacitor checker or basic DVM. 99 times outta 100, it is just glue! Plus it is highly unlikely that 2 or 3 or more just happened to spew at the same time.

So for the moment, forget about the capacitors and concentrate on the main power problem and look at the suspects mentioned first. Once you get it working again, it may not need any capacitors replaced but people do so just because it is 30 years old or older.

I am still using some 50 year old amps with their original cans. They are still holding up but who's to say what tomorrow will hold.
 
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I had a JVC 125w integrated in my possession (AX something IIRC), that had obviously leaking main filter caps. Wouldn't reproduce bass for crap.
 
The "leaking" on the caps is probably assembly glue.

If you haven't owned the unit since new, who knows what its been through.
leakage.jpg
Notice the brown material under the 50volt Caps just to the left of the power transformer ? Is that not leakage or is that discolored assembly "glue" ? This brown material is under at least 6 of the Caps on this unit. I can't see any other damaged components. Not even so much as small pieces of ceramic from any blown wafer Caps. All fuses test good as far as continuity, but I did not test them in circuit yet.
Thanks for your response in advance.
 
I don't want to bother you all to be "spoon fed" here. The unit is relatively cheap and can easily be replaced, but then that would defeat the entire purpose of the learning experience. lol =)
 
I would check the power switch, I seriously doubt the transformer is damaged. Blaine is excellent at this stuff so I expect if this is something easy, he will figure it out quickly. If the fuses are not blown then nothing else in the EQ would affect power up of the unit, it could be the switch or a bad solder joint/connection on the PS board
 
I would check the power switch, I seriously doubt the transformer is damaged. Blaine is excellent at this stuff so I expect if this is something easy, he will figure it out quickly. If the fuses are not blown then nothing else in the EQ would affect power up of the unit, it could be the switch or a bad solder joint/connection on the PS board
I guess it would have been prudent to check the power on indicator bulb. It isn't any good. lol Damn how easy is that ? Now the receiver I am using does not have a preamp out, so from what I understand is I am supposed to connect my RCA cable from source to TAPE/REC OUT on EQ and then connect my RCA cable from TAPE/ PLAY BACK from the EQ to VCR/TAPE 2 MONITOR IN on my receiver, am I correct by this assumption ?
 
Or tape 1, unless you already have a tape deck there, but yes! :thumbsup:

Lol, I'm too lazy to go back and read the thread, but didn't someone mention a bad bulb? :p

I have a Marantz EQ that was given to me where the person said it wouldn't work or light up. I just plugged it in and connected it to my stereo and it worked. :D Just a couple of burned out bulbs behind the panel.
 
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If the bulb is burnt out the negative side of the power supply voltage is affected. I too had one that appeared to not power up. I replaced the bulb and after some playing with dirty switches, the record switch especially, it works just fine.

I get this thread is OLD but someone may find this useful.
 
They were on a AK list of potential problematic one's. 14 (two per slider) on each band and a couple others. New Ksc1845's mostly.
 
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