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Post subject: 2004 Blues Deluxe RI no drive function
Posted: Sat Mar 12, 2016 12:43 pm
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Hi ya'll , how r ya doing? great! I've got a BDRI here and it has no drive function. I don't like to call it a channel as it really is not a separate channel. So. I've checked all the voltages and tubes according to the repair manual, and they are all spot on. Tubes are fine. The problem is on the main board and has to do with the drive channel only.
I have suspected it has something to do with K2. I just temporarily jumpered k2 contacts 4 and 8 and 9 and 13 and now I have drive responding to the drive pot and master. But it is still subdued, not very loud. So I think K2 is bad, but why the decreased volume? Any ideas or help is welcomed.
The normal channel works fine and gets very loud. the voltages at all the test points are good. The mute is working, etc. Tubes all known good. The problem IMO is just related to the relays or the drive specific components.
thank you in advance for the help. :-)


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Post subject: Re: 2004 Blues Deluxe RI no drive function
Posted: Sat Mar 12, 2016 4:32 pm
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I believe your diagnosis is spot on. These *mode-switching* amps (which is what these designs really are) are known to malfunction periodically due to a failed relay. Replacing K2 will likely restore the "channel-switching" function.

Arjay

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Post subject: Re: 2004 Blues Deluxe RI no drive function
Posted: Sun Mar 13, 2016 4:38 am
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I would verify whether or not you have the DC voltage at the relay first. In fact, check your +/- 16 volt supplies, as the missing supplies are usually the culprit. If supplies not there, it is likely broken solder joint(s) or a broken trace in the supply area.

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Post subject: Re: 2004 Blues Deluxe RI no drive function
Posted: Sun Mar 13, 2016 5:32 am
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thanks retro - I'm ordering some relays and will let you know meantime I think I will de-solder it and pull it and just jump across the drive contacts to see if the volume level comes up. Question? since I have never heard a properly functioning drive mode, how loud can it get in comparison to the clean mode?

shimm - both relay coils are getting voltage , it's TP32 on the list to check (bottom right of the schematic page) the contacts are passing the clean signal (normal mode) but not passing the drive signal and/or not switching in/out the drive pot. The test point is TP32 and my check reveals -16vdc with drive signal in and + 7.5 out.


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Post subject: Re: 2004 Blues Deluxe RI no drive function
Posted: Sun Mar 13, 2016 8:38 am
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Why I opened this thread was because I was unsure if bluesky would be accepting of my posting in his BDRI mod thread. There is a duplicate thread ongoing there and I think this thread should be ended.
Please lets post there and not here. Mods you could delete this thread. Thank you.


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