| Kasino Concert Guitar Head/ Model Con-L [message #26685] |
Sun, 06 May 2018 20:53  |
leejy
Messages: 1
Registered: May 2018
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Junior Member |
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To all of you last geniuses of the analog era.
I have a Kasino Concert Guitar Head that I am trying to restore. The reverb is not working. The pan is OK everything is connected and I am able to hear the reverb output but the input is not being fed into the unit. The reverb works great if I feed it from an external device... Also the tremolo section is not working. All I get is a few db volume increase when I turn the depth potentiometer.
I got the feeling that a chip is dead or a capacitor...
Any suggestion?
The chip says 5558. Where can I find a replacement?
Any input would be greatly appreciated.
Thanks for reading
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| Re: Kasino Concert Guitar Head/ Model Con-L [message #26686 is a reply to message #26685] |
Mon, 07 May 2018 06:53  |
stevem
Messages: 4775
Registered: June 2004
Location: NY
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Senior Member |
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I think your Tremolo not working is a result of what's wrong with the reverb send also.
If you can read the schematic on this site in our technical section for the PC5068 board and have a voltmeter then check for the minus 12vdc on that 5558 chip , as a bet a bad electrolytic cap on that board is sucking down that -12 volts.
You can also do a simple test of the drive amp to the pan if you have another amp.
Feed the signal from the rca on the input side of the pan and see if you get signal into the other amp.
Hopefully you will not have to track down a expensive NOS 5558 chip!
You might also plug and unplug a few times the white multi pin connectors that feed both power and sign in and out of that board as the Aluminum connector pins used in them get can get very tarnished up with age and not make connection.
In other words the needed drive signal may not even be getting into that 5068 board!
[Updated on: Mon, 07 May 2018 07:41] Report message to a moderator |
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| Re: Kasino Concert Guitar Head/ Model Con-L [message #26687 is a reply to message #26685] |
Mon, 07 May 2018 12:34 |
chicagobill
Messages: 2006
Registered: April 2003
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Senior Member |
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Welcome to the place.
As Steve suggested, check the connectors and the power supply voltages first. I will assume that the PC board in question is the PC5068.
The standard way to test op amp chips is to read the voltages on the output pins. In the case of the 5558 that would be pins 1 and 7. There should be little or no voltage on either pin of IC3, which is the reverb chip. If there is, it may be bad.
The 5558 is a dual op amp also known as a 4558, etc. It can be replaced with almost any standard 8 pin dual op amp like a 4560 which is the reverb driver chip that Fender likes to use.
The tremolo/vibrato has two parts to the circuit. One, the low frequency oscillator and two, the modulator. The LFO is based around IC6 and the modulator around IC4 and IC5.
Check to see if the LFO is working by measuring the ac voltage at pins 1 and 7 of IC6. If you have access to a scope, you can also look for the waveform at these pins. The schematic lists an 18 v.a.c. signal at these points.
If the LFO is working, see if the LFO signal is getting to the modulator chips at pin 5 of IC4 and IC5. If the signal is getting to the mod chips, then they may be bad. It would be unusual for both to go bad at the same times, so be sure to test power supply voltages first.
Good luck.
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