MARKBASS MINIMARK 802 - What is that relay ?

[smurtz]

Hello,

I got hold of a non working bass amp Markbass minimark 802, witch stays dead when turned on.
Before checking anything else, when opening, the first thing I see is a broken relay:



What would be the replacement part ?

I tried to look on the schematic of a similar markbass amp >HERE< but nothing is mentionned except "RL1".


On the remaining part of the relay we can still read "8A" but thats about all.

Would it be a G2RL relay (>HERE<) but which one ? (a G2RL-24 DC24 ?)


Thanks a lot for your help.

Yves

[madan1]

Re: MARKBASS MINIMARK 802 - What is that relay ?

Seems to be on the amp side and I would guess it disconnects the speaker from the amp so that there is no pop sound when the amp is turned on.

PS
Here https://cdn.badcaps-static.com/pdfs/...ceb5b3feac.pdf page 14, RL1 right next to the speaker connection. Just shunt it for troubleshooting and if it is the cause, then anything that fits the footprint and the control signal level (18v) should do the work.

[petehall347]

Re: MARKBASS MINIMARK 802 - What is that relay ?

check voltage at the 1 meg resistor R68.ideally 0v . i guess protect kicks in about 3v . maybe less .

[CapLeaker]

Re: MARKBASS MINIMARK 802 - What is that relay ?

Speaker protection relay? Should be normally open.
If you turn an amp on you should hear a click (if everything is o.k.)

The relay you chose is normally closed.

[smurtz]

Re: MARKBASS MINIMARK 802 - What is that relay ?

Thanks a lot, I ordered the relay.
Tried to shunt it, but no effect. Current goes to transformer TRANS5_1_1 but not past it.
I first thought the transformer was dead and unsoldered it to test it, but it seems ok.
However since enough room was left without the transformer I was able to test capacitor C68 (1uF/250V) which (unsoldered) reads 209nF.

Hopefully it'll work again once that capacitor+relay changed. More news when I receive the parts.

Yves

[lotas]

Re: MARKBASS MINIMARK 802 - What is that relay ?

Photo from the Internet, 12v relay.

[smurtz]

Re: MARKBASS MINIMARK 802 - What is that relay ?

excellent, thanks!
Yves

[smurtz]

Re: MARKBASS MINIMARK 802 - What is that relay ?

I changed C68, switched on, and tada ! Well, tada, now the fan starts, the on led is off.
On the board I have the +15V.
the led clip is on. I did not reconnect speakers when switching on.

I had to order a new relay since I ordered a 24V before seeing lotas' message.
Once I receive the relay I'll do some more checks.

Yves

[smurtz]

Replaced the relay, but nothing new.

When I switch the amp on, the fan starts and I hear the relay click once (r68 voltage is 0).
The led "clip" is on, the led "on" stays off.
When I turn the amp off, I hear the relay click once

On schematic page 15:

near C53 I have +15V -> ok
near C59 I have +12V -> ok
near C41 I have +19V (marked +18V on the schema)
near C62 I have 0V (marked -15V on the schema) ->I have -20V measured at Vin on regulator RG2, I checked regulator RG2, seems ok but I'm going to change it to be sure.
near C45 & C46 I have +58V and -58V (+80V & -80V on the schema)

Could the +/-58V be ok ? or the 4 RF2001s (D24/D25/26/27 marked BYV32E on the schema) should be replaced ?


Thanks
Yves

[CapLeaker]

Either you got a bad 7915 regulator RG2 or something is shorting the -15V rail to GND.

[smurtz]

Thanks,

I changed the 7915, checked for shorts, switched on and it immediately got me a fume.. Fuse F1 is now broken.

However C65 (2200uF capacitor) seems to be the one that was causing the problem, I'm going to change it as well.


Any clue of what is the value of the fuse / what kind of fuse it is ? It looks like a resistor.

Yves

[CapLeaker]

F1 is probably same as F2 and may be a fusible resistor. Size makes the wattage. Make a picture of it?

[smurtz]

Unfortunately, contrary to what is mentioned on the schematic there is no F2 or F3 fuses !

EDIT: seems to be a R = 0,22 Ω ±5 % 250 ppm/°K