HT-20 Head problem with volume stability on overdrive channel

[ai3time]

I have noticed very annoying volume issue on my HT-20 head. It appears on overdrive channel only.
When I'm playing with gain, then volume seems to be unable to keep given level of loudness. Initially it goes very noise then after few moments of playing instantly get significantly lower. Does not matter what level will be set on override volume knob - effect will be respectivelly the same. You can only imagine how much iritating that is. Recently I recognized that pushing or moving a bit OD volume knob restores initially set volume. Unfortunatelly this does not help for long time; soon after volume decreases. For me it seems to be kind of short circuit, but I'm not expert. Maybe someone of you had similar problem and can give me a piece of advice what should to be done?

My equipment has more than two years already, so I believe that guarantee already expired. I bought this wonderful head amp in Thommass.De store. Here in Poland, where I live, there is no chance to met any blackstart service partner. Any help would be welcome.

With best regards

[majikmojo]

tube check ? - 2 years on original tubes?

[ai3time]

tube check ? - 2 years on original tubes?

Yes, the same tubes from begining. Two years, already.
Sorry for lame question: how to check tubes?

Thank you

[majikmojo]

tap on the power tubes with a pencil to see if you have a microphonic one...you will hear a strange sound coming through
if so...

you may just need some new valves - i dont know how much you use it or how hard but after
2 years of steady hard use they may be a bit weak

[IM4Tone]

I had a similar problem w/ my HT20 Head. I initially blamd the tubes and changed them, but it turned out to be a bad solder joint. Warranty repair station fixed it for me. Don't know if B* warranties are the same in all countries, but in the USA, warranty is 3 years if registered. Tubes are only 90 days.

[I Wanna Rock]

Doesn't happen on the clean channel?

It could be a bad solder joint on that volume pot, or even a failing or dirty volume pot. Try turning the suspect volume knob all the way left and right a bunch of times and see if it helps stop the volume loss temporarily.

[ai3time]

Doesn't happen on the clean channel?

It could be a bad solder joint on that volume pot, or even a failing or dirty volume pot. Try turning the suspect volume knob all the way left and right a bunch of times and see if it helps stop the volume loss temporarily.

Thank you for advice.
Not, this issue does not appear on clean channel. It is a metter of overrdrive only.
Done what you have suggested. I also applied compresed air cleaner to clean volume pot. No positive results. Most probably as you wrote it may be broken knob or bad solder joint.
I have to contact with Balckstar to get information about service support in my country. Will let you know about results.

Best regards

[ai3time]

I had a similar problem w/ my HT20 Head. I initially blamd the tubes and changed them, but it turned out to be a bad solder joint. Warranty repair station fixed it for me. Don't know if B* warranties are the same in all countries, but in the USA, warranty is 3 years if registered. Tubes are only 90 days.

Thank you. I'm going to contact Blackstar and Thomann.De with question about my warranty period. I will also ask Blackstar about the way of service organization for my country - I believe that there is no repair station here and most probably I will have to send my amp somwhere in Europe.

Thank you

[ai3time]

For others fans of Blackstar amps from Poland:

1. Here warranty period is also 3 years, like in other UE countries.
2. Service for Blackstar amps is indirectly provided by stores and shops.

Everything what have to be done is pack and send amp head to shop. In my case thomann.de is covering whole shiping cost (again I'm suprised by superb quality of their customer communication and services). My amp head is going to be reviewed and most probably knob will be replaced.

Topic closed.
Thank you all for support.

[nahar]

Hi ai3time, looks like my ht20 is going thru the same problem with the gain channel. It happened last year and i got it fixed under warranty by the distributor. After a year plus the problem replicated. Now that the warranty is gone, would appreciate if you could share the cause of the problem and the solution to it.