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Need help troubleshooting a Kasino U100-P [message #27089] Wed, 07 November 2018 00:48 Go to next message
muddy udders is currently offline  muddy udders
Messages: 6
Registered: November 2018
Junior Member
I recently picked up a Kasino Club PA head. It works but isn't very loud. All channels seem to be the same no difference, all knobs do what they are supposed to tone wise, Reverb works. I believe I can rule out individual channel boards as they all are equal in volume.
I have the schematics for each board and have been probing the PC900 output board for voltages and everything is close. I see no obvious burned components or bad solder joints. I do see -38v on Q2 BLU which is the base of the 36892. Would this be normal? Schematic shows -.1
I removed both Q1 and Q2 tested them Q2 was hFE=35 Vf=526mV Q1 was hFE=25 Vf=517mV
I put them back in swapping positions and Q2 BLU voltage remained -38v.
If you haven't figured it out yet my skill level is beginner/intermediate. I have built a couple pedals from scratch and in the past built a pirate FM radio station. I know enough to most likely not electrocute myself, no promises though.

Any and all help would be appreciated.

Thanks,

Robert/Muddy
Re: Need help troubleshooting a Kasino U100-P [message #27090 is a reply to message #27089] Wed, 07 November 2018 06:03 Go to previous messageGo to next message
stevem is currently offline  stevem
Messages: 4112
Registered: June 2004
Location: NY
Senior Member
That voltage would seem normal since it's being fed off of the 100 ohm resistor that has the -39.5 supply voltage on it.
I would next check the two 5 watt 1 ohm resistors to see if they are open as these just can go open yet not burn.
Re: Need help troubleshooting a Kasino U100-P [message #27091 is a reply to message #27089] Wed, 07 November 2018 13:04 Go to previous messageGo to next message
chicagobill
Messages: 1890
Registered: April 2003
Senior Member
Agree with Steve, I think that you have misread the schematic. The -0.1 volt is for the Collector of Q1 not the Base.

Have you tested all of the dc voltages from the power supplies?

I'd want to test your theory about the problem being in the power amp before you do too much work here. All of the preamps are of equal loudness, but they all go through the reverb/mixer board, so the problem could be there as well.

Feed a signal into the power amp at the monitor point. I don't remember if the Casino has a jack there or not, but in any case, there is a point on the pc board. See if you can drive the power amp to a higher loudness level than you are getting from the preamps.

If you don't have a signal generator or some sort of phone app, you can use the signal from another amp or a guitar with a boost pedal of some sort, or even an MP3 player.
Re: Need help troubleshooting a Kasino U100-P [message #27092 is a reply to message #27089] Wed, 07 November 2018 14:39 Go to previous messageGo to next message
muddy udders is currently offline  muddy udders
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Registered: November 2018
Junior Member
The 1 ohm resistors are in spec.
The PA has monitor and tape inputs. I used my phone through both and the sound was clear and louder. When I put it through the front input jacks, I tried them all, the sound was lower and very distorted. Does this mean my issue is on the reverb board?
Re: Need help troubleshooting a Kasino U100-P [message #27093 is a reply to message #27089] Wed, 07 November 2018 20:03 Go to previous messageGo to next message
muddy udders is currently offline  muddy udders
Messages: 6
Registered: November 2018
Junior Member
The 1 ohm resistors checked in spec.
I hooked up my cell phone to the Monitor jack on the back and the audio was real clear and seemed louder.
I connected through the front inputs and it was quite distorted and not as loud.

The DC voltages on the PC900 board were correct for 8v and 39v. I forgot to check the reverb board voltages.

Does this confirm your theory Chicagobill?
Re: Need help troubleshooting a Kasino U100-P [message #27094 is a reply to message #27089] Thu, 08 November 2018 06:02 Go to previous messageGo to next message
stevem is currently offline  stevem
Messages: 4112
Registered: June 2004
Location: NY
Senior Member
On the Reverb board ( pc803) lift either end of C804 and see if the volume level goes up .
Re: Need help troubleshooting a Kasino U100-P [message #27095 is a reply to message #27093] Thu, 08 November 2018 13:09 Go to previous messageGo to next message
chicagobill
Messages: 1890
Registered: April 2003
Senior Member
muddy udders wrote on Wed, 07 November 2018 19:03
The DC voltages on the PC900 board were correct for 8v and 39v. I forgot to check the reverb board voltages.

Does this confirm your theory Chicagobill?
Yes, it seems that the power amp is working correctly and the problem is either the reverb board or the low voltage power supply. I don't think that all four preamps would fail at the same time in the same way, unless something unusual happened or was done to the amp.
Re: Need help troubleshooting a Kasino U100-P [message #27096 is a reply to message #27089] Thu, 08 November 2018 15:49 Go to previous messageGo to next message
muddy udders is currently offline  muddy udders
Messages: 6
Registered: November 2018
Junior Member
Sorry for the double post. I didn't catch that all my posts need to be approved. I thought I had hit the wrong button when the first post had not shown up.
I ordered parts and I will recap the reverb board and see what I get. Where does everyone source parts? I have been using Mammoth, Mouser and circuit specialists even amazon for some stuff. Just looking for vendors.
Thanks for all the help so far i will post up what o find.

Robert/Muddy
Re: Need help troubleshooting a Kasino U100-P [message #27097 is a reply to message #27089] Fri, 09 November 2018 12:53 Go to previous messageGo to next message
muddy udders is currently offline  muddy udders
Messages: 6
Registered: November 2018
Junior Member
One more question. It appears that most of the caps are 10uf except the single 1.0uf. Am I reading this right?
Re: Need help troubleshooting a Kasino U100-P [message #27098 is a reply to message #27089] Fri, 09 November 2018 23:12 Go to previous messageGo to next message
muddy udders is currently offline  muddy udders
Messages: 6
Registered: November 2018
Junior Member
I recapped the 803 reverb board all the electrlytics replaced. The sound is better, not distorted like before. I still don't believe it is as loud as it should be. I am putting this into a crate 412 cabinet, if I put my stereo into the cabinet it is much louder.
Any thoughts?
Re: Need help troubleshooting a Kasino U100-P [message #27099 is a reply to message #27089] Sat, 10 November 2018 06:21 Go to previous message
stevem is currently offline  stevem
Messages: 4112
Registered: June 2004
Location: NY
Senior Member
Yes, you have the caps right!
What impeadance is the 4-12 cabinet?
The amp wants a 8 ohm load to output its full clean 50 watts of RMS audio output.
If your 4-12 cab is 4 or 16 ohms then you will only have 25 watts of clean output to work with.

You should be seing some 18 to 20 volts of unclipped audio output at the amps speaker output into a 8 ohm test resistor / speaker load if all is well!

[Updated on: Sat, 10 November 2018 06:24]

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