Hi Guys,

I've learned so much reading here, from time to time I come back here to read the new posts.
My Sub died on me, time for the overhaul, going to mod the PSU like the (legendary) MichaelD did. Parts arriving next monday I hope.
My only question so far is, what is the recomended wattage to remove the snapins? I don't want to rip the lands or the tracks and do a bad job.

Thanks for all the teaching!!!

I used a 60w iron, the snapins are a pain to remove, but I did it. Unfortunately the glue damaged alot of tracks that I have to rebuild also caused some shorts, I have to replace D9 with a 1N4007 instead of a 1N4004. The tracks between C70 and C69 are gone. Is there any type of Lacquer you recomend to increase insulation?
On the mosfets on the primary side, can I use silicon insulation or do have to use the ceramic ones due to capacitance? They are too britle.

Thank you.

Relay doesn't click. On CN6 I have 5vdc on pin1, maybe C53 is pulling the voltage down or 7809 is not working properly (I have 12Vdc on the input).
Also missing +-24 on CN4 and 5
Some pointer would be great, I can't remember the last time I had to repair a circuit.

Thanks once again.

I have a green light on the control pods

I have the proper voltage on the input of 3 voltage regulator, on U6 there is no input voltage, I checked R45, no voltage either, is possible I have a broken transformer?

When I get home with a soldering iron I measure them outside the circuit.

Thanks.

Working again! My problem was a shorted D9 (replaced to 1N4007)
C53 was pulling 9vdc down, no voltage to drive the relay.
Also had a broken track before R45, reason why I had no -24vcd
U3 was dead, but I had a 24V Psu lying around, easily fixed.

This is a PSU from hell!!!
Ordered your part list and some other stuff I want to change, Do you recomend any silicone to hold the caps in place?
Now to take all of the glue from the remaining boards

Correct me If I'm wrong, long time I don't repair anything like I said, Looking at the schematic I would say these are 3 psu on a single pcb, correct? AUX psu controls the power up of PSU1 and PSU2, I could remove the control board and drive the amps directly. (my control board looks awful, full of brown glue)

Thank you!

Hi,

New problem, I hae voltage, relay clicks, power goes in the amps, but no sound, not even noise om any of the channels
Dead APB?.
Control pod looks to be working, leds go up and down, but no sound.
How can I troubleshoot this?

Thanks

Hi,

Thanks for the quick reply.

I think I still have problems with the PSU, no noise, no hissing, on both Amp boards.

Can you tell me what are the proper voltages and pinout of CN5 and CN4? I don't have the complete shcematic of board.

Thanks.

Hi,

Exactly what I needed.
24Vdc to CN5 comes from the track in CN4, It was broken. When I measured it was fine, when I insert the plugs it opens, that was easily fixed, but ground pin in CN4 was to oxidized (too many years with crappy soldering I guess), impossible to solder.
I end up placing rivets on the holes of CN4, solved the problem and increased the resistance.
I recaped the APB, that is working great

On to the AMPS

Thanks

Hi,

It is partially working.

PSU is working ok, but I don't have the socket to insert in CN4, so I'm testing one board at a time.
I have distortion in one of the boards, I know it is the amp because I swaped the signal cable between the amps and the distortion stays in the amp card.
I suspect some bad caps.
I'm waiting now on parts, caps for both amps and psu, also waiting for plugs and sockets to replace most of the connections.

Here you have a pic of what I did on CN4

Thanks

https://ibb.co/jfmx6sD

Hi guys,

Broken again, even before the new parts arrived.
Now I have no voltage on both 70V rails

Relay is clicking and control pod works perfectly.

Whats the usual suspect in this situation?

Thanks.

Hi,

Q4 is shorted, is that enough to kill both rails?

Thanks

Never mind, had a look at the schematic.

No need to answer.

Thanks MichaelD!!!

haha

Going to replace all of them, if this happened to one, can happen to the others.

https://www.digikey.pt/product-detail/en/vi...BPBF-ND/4437991

or

https://www.digikey.pt/product-detail/en/vi...0APBF-ND/812040

What would you recommend?

Going to replace the diodes also, is this a good replacement? Looking at the specs it looks like it, right?

https://www.digikey.pt/product-detail/en/vi...45GI-ND/2152878

Thanks for the help!

Thank you for the recomendations.

I'm going to modify and replace the heatsink of the PSU and both amp boards.
Going to connect the 3 boards directly to the backplate to better dissipate heat, also going to installl a temperature controled fan on the outside of the sub.
Is there any reason why I should't connect the 3 heatsink to the backplate?

All the voltage regulators, mosfet and diods are insulated thru the ceramic lumina, right?


Thanks

Hi MichalD,

I was starting the refurbish of the amp boards and I noticed something that I would like you to comment.

I always thought the RCA output on the back were center pin positive, but I see center pin negative.

On the output of the amp boards you have the pcb marking -+ but the connection for the sub are the other way around, is it just me or is this a fault? could explain why so many damaged subs

Thanks

Hi,

True, I always forget speakers are AC not DC, but I didn't mentioned the other issue I was thinking, phase shift, since they are wired the oposite way, the speakers can cancel part of the sub frequency.
I'll rewire everything the same way, thanks for the reminder.