Hey All,
I've had the Hot Rod Deluxe to ODS drop in board for a little while now and finally took it to a tech because I don't have the time or the skill to finish it up. The mods that were done were the Voltage Bias Mod and the PAB HRM Mod. That's it.The tech told me that he can't find 15v anywhere but has -24v everywhere and that none of the relays work. The clean works but no relays function at all. Please Help!!
Bought the board around this time last year; I think it's a Rev. A. (Verified: Definitely a Rev. A)
jinx1499 wrote: ↑Tue Mar 24, 2020 12:20 pm
Hey All,
I've had the Hot Rod Deluxe to ODS drop in board for a little while now and finally took it to a tech because I don't have the time or the skill to finish it up. The mods that were done were the Voltage Bias Mod and the PAB HRM Mod. That's it.The tech told me that he can't find 15v anywhere but has -24v everywhere and that none of the relays work. The clean works but no relays function at all. Please Help!!
Bought the board around this time last year; I think it's a Rev. A. (Verified: Definitely a Rev. A)
Some photo's of the board connections, and that type of thing would really help. The schematic I have is for Rev B, but basically look at the schematic for yours. You should see 15V coming out of the voltage regulator. on mine I have a TP5 that says it should be 15V.
Basically the 60V winding that comes off of the brown wires on the amp is the bias winding, and it pulls that into a few diodes and droppers etc before feeding into a voltage regulator that drops it to a consistent 15VDC out
Another thing to ensure you got right is to have jumpered the board section for the seelction of which footswitch features to use on the footswitch vs on the panel only. The foot switch uses a stereo jack so it can only switch two things on/off and so you must select to do one of OD/Mid/PAB and leave the one you don't want on a footswitch as the 'panel only' jumper if you did those wrong or didn't do them, it may leave it not working.
Let me know what looks off or if you need more details of a certain area.
I haven't touched anything since getting it back from the tech, so this is exactly what he was seeing when he told me about the voltage issue.
Let's look at the low voltage (switching) power supply. Please report AC voltage with respect to ground at point indicated by 1 on the attached schematic, and measure DC voltage at points 2 and 3.
snip1.png
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I build and repair tube amps. http://amps.monkeymatic.com
It is impossible for there to be 0.05 VAC at point 1 and then 18VDC at point's 2 and 3.
Did you set your multimeter to VAC when testing point 1 as he asked? I'm thinking you left it on VDC. 18VDC is a bit high and maybe part of the problem? you're also showing -18.5VDC. Did you accidentally put the red lead on the chassis and the black lead on that point? Because if you're really reading negative volts there's even more going wrong there.
I see you have jumpered out D15, which is correct for the HRD converstion. D16 is reversed biased (attn: Phil) so the DC voltage after D16 is supposed to be negative voltage, as that's what U10 wants to see.
Please double check DC voltage at point "2" and make sure it's negative, WRT ground. If it's not, I suspect D16 is fried.
I build and repair tube amps. http://amps.monkeymatic.com
From the pictures, it looks like all three relays are plugged into their sockets backwards. Please confirm. It also looks like the OD entrance trim pot (TR2) is wired to a panel mounted pot with non-shielded wire. This will likely prove to be problematic, and you should consider replacing the three wire runs with a shielded, twisted pair cable. Use the shield for the GND connection (bottom, left terminal when viewing the board as right-reading - I tried to post a screen shot, but it looks like it didn't come in. But if it did, the GND terminal is highlighted in yellow).
Also, you can feel free to connect with me via email (in my profile) as you most likely bought the board from me and I am happy to help out with the build.
