Help needed diagnosing HRM Drive issue. Fixed

[Guitarman18]

Hi all,

I built this amp for a friend about 3 years ago (my 5th D'clone build) and until recently it has been in constant use and functioned without issues.

Now, however, when switching to the OD channel, there is no Overdrive. By matching the volume to the clean channel, the OD channel sounds almost identical.
The Drive and Volume pots both function, as do the relays and the manual switches, so does the OD trim pot.

I have traced the entire OD section and can't find any anomalies. As far as I can see the connections are still sound. V2 has been swapped, but without any change in performance. V2 voltages are all within expected range (plates @ 205V and cathodes @ 1.5V.

It literally sounds as though the switch doesn't work, because the sound stays the same with no real boost in gain, however I know it has switched because the OD controls become functional.

So, does that mean that some part of the OD section is grounding inadvertently?

I've spent the last few days scratching my head trying to figure this out, but I have to confess it has got the better of me! I can't help thinking that it must be something simple (dry joint or something) but for the life of me I can't find it.

If anyone has any suggestions or could point me in the direction of a post where a similar issue has been discussed, I'd really appreciate it.

Many thanks in advance for any help anyone can offer.

Cheers,

Paul.

[Guitarman18]

Turns out that, after a second pass on the solder joints, it was a dry joint after all.

Thanks for looking.

Cheers,

Paul.

[Structo]

Good job finding the problem.
Sometimes they can get the best of us.

Do you like the HRM better than a regular ODS?

[tubedogsmith]

What are your heater voltages running on the tubes? Just going by color it looks like you're running a rectifier 5v heater for your tubes and running your relays off the 6.3v tap.

[ToneMerc]

What are your heater voltages running on the tubes? Just going by color it looks like you're running a rectifier 5v heater for your tubes and running your relays off the 6.3v tap.

Ditto

TM

[Guitarman18]

tubedogsmith wrote;

What are your heater voltages running on the tubes? Just going by color it looks like you're running a rectifier 5v heater for your tubes and running your relays off the 6.3v tap.

It is a custom Heyboer Vibrolux PT with 2x 6.3v taps. Having the extra voltage was particularly useful at one gig I did where the generator was running under voltage. It meant that my #124 (which runs relays off a 5V tap) just didn't have enough beans to switch.

Structo wrote;

Do you like the HRM better than a regular ODS?

I haven't spent a lot of time with this amp, but I have to say the cleans are really nice (no LNFB on HRM- my preference on lower wattage setup) and the range of control over the OD is really useful. I will be building one for myself pretty soon. I have a hard time deciding which version I prefer, and so I end up having one of almost all iterations.

Cheers,

Paul.