DSL 50 overheating problems

Benjamine1979 · 10-28-2008, 06:18 PM

Hi Gurus,

Can anyone advise me about a problem I am having with my DSL head. I was playing it a while ago when it lost most of its power. So I changed the valves. However using the guidance from Eurotubes I tried to bias the amp. However the voltage just seems to keep rising and now matter how low I turn the pots down it seems to not go below 450mV. I have seen that it should be running 90 mV so I guess there is something else quite bad up with the amp. Can anyone point me in the right direction??

Or failing that does anyone know of any good amp repairers in the North West of England??

Ta

Ben

zeusecho · 10-29-2008, 07:25 AM

Hey dude sorry about your DSL. I live in the US so I can't help with a tech in England but the DSL50 should be biased to 35-45mV not 90mV. The 90mV is for the DSL100. It's hard to believe that you actually have 450mV bias, that would be total meltdown. You should check the meter to make sure it's accurate and set correctly to mV reading not V reading. If it's on Volts and your reading is 0.045V that is actually 45mV.

Benjamine1979 · 10-29-2008, 08:52 AM

Hi zeusecho,

Thanks for the reply - That is a very good point. I will check tonight to see if I am just being a muppet!

Benjamine1979 · 10-29-2008, 05:07 PM

Hiya,

I have made a mistake in the title of the post, the amp is actually a DSL 100. I have had a good play around with it just and still have the following problem.

After about 5 mins I set the bias to 90 mV. All looked fine - however after five more minutes it had crept up to 120 mV. So a little more tweaking of the pots and I got it down to 100 mV but that was as far as the pots would go. Then five more minutes it was up to 160 mV. I decided to switch it off at that point.

Any one got any ideas if this is a serious problem or not??

Ben

zeusecho · 10-29-2008, 05:33 PM

I have heard that DSLs can have that problem but I don't know what the root cause is.

I think there is a suspect CAP on tube plate circuit...you may want to do some Google searches on it because I found several Forums discusing this issue in the past.

I have also heard that if the power tubes are not burned in correctly that they can drift.

FWIW...All of the above is hearsay as I have not experienced that problem myself.

metal_hit · 10-29-2008, 06:11 PM

Hi man,
take a look at that The Marshall TSL122-JCM2000 Repair/Mods Page

Benjamine1979 · 10-30-2008, 09:31 AM

Cheers guys - the link looks like the problem

Benjamine1979 · 10-31-2008, 06:42 AM

Hi All,

So it looks like Marshall recommend to replace the main board. Is this a simple thing or would it be better to send it off to marshall??

Also has anyone recent bought a board off marshall? if so how much??

Ben

Benjamine1979 · 11-01-2008, 05:30 AM

Quote:

Originally Posted by llh11456

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eh?

Benjamine1979 · 11-05-2008, 05:21 PM

well, one new board later and that seems to have done the trick - 20 mins and still 90 - :-)

luekemeyer · 11-09-2008, 04:18 PM

How much for the main board?

10-28-2008, 06:18 PM	#1 (permalink)
Benjamine1979 Junior Member Join Date: Oct 2008 Posts: 9	DSL 50 overheating problems Hi Gurus, Can anyone advise me about a problem I am having with my DSL head. I was playing it a while ago when it lost most of its power. So I changed the valves. However using the guidance from Eurotubes I tried to bias the amp. However the voltage just seems to keep rising and now matter how low I turn the pots down it seems to not go below 450mV. I have seen that it should be running 90 mV so I guess there is something else quite bad up with the amp. Can anyone point me in the right direction?? Or failing that does anyone know of any good amp repairers in the North West of England?? Ta Ben

10-29-2008, 07:25 AM	#2 (permalink)
zeusecho Senior Member Join Date: Oct 2008 Posts: 170	Re: DSL 50 overheating problems Hey dude sorry about your DSL. I live in the US so I can't help with a tech in England but the DSL50 should be biased to 35-45mV not 90mV. The 90mV is for the DSL100. It's hard to believe that you actually have 450mV bias, that would be total meltdown. You should check the meter to make sure it's accurate and set correctly to mV reading not V reading. If it's on Volts and your reading is 0.045V that is actually 45mV. __________________ Marshall DSL50 H&K Switchblade 50W Combo Line6 4x12 (Hellatone 30s and 60s X pattern) Gibson LP Custom ESP MH-301 Merz Custom Acoustic Taylor 355ce 12 String

10-29-2008, 08:52 AM	#3 (permalink)
Benjamine1979 Junior Member Join Date: Oct 2008 Posts: 9	Re: DSL 50 overheating problems Hi zeusecho, Thanks for the reply - That is a very good point. I will check tonight to see if I am just being a muppet!

10-29-2008, 05:07 PM	#4 (permalink)
Benjamine1979 Junior Member Join Date: Oct 2008 Posts: 9	Re: DSL 100 overheating problems Hiya, I have made a mistake in the title of the post, the amp is actually a DSL 100. I have had a good play around with it just and still have the following problem. After about 5 mins I set the bias to 90 mV. All looked fine - however after five more minutes it had crept up to 120 mV. So a little more tweaking of the pots and I got it down to 100 mV but that was as far as the pots would go. Then five more minutes it was up to 160 mV. I decided to switch it off at that point. Any one got any ideas if this is a serious problem or not?? Ben

10-29-2008, 05:33 PM	#5 (permalink)
zeusecho Senior Member Join Date: Oct 2008 Posts: 170	Re: DSL 50 overheating problems I have heard that DSLs can have that problem but I don't know what the root cause is. I think there is a suspect CAP on tube plate circuit...you may want to do some Google searches on it because I found several Forums discusing this issue in the past. I have also heard that if the power tubes are not burned in correctly that they can drift. FWIW...All of the above is hearsay as I have not experienced that problem myself. __________________ Marshall DSL50 H&K Switchblade 50W Combo Line6 4x12 (Hellatone 30s and 60s X pattern) Gibson LP Custom ESP MH-301 Merz Custom Acoustic Taylor 355ce 12 String

10-29-2008, 06:11 PM	#6 (permalink)
metal_hit Junior Member Join Date: Oct 2008 Location: Bulgaria Posts: 21	Re: DSL 50 overheating problems Hi man, take a look at that The Marshall TSL122-JCM2000 Repair/Mods Page __________________ www.myspace.com/metalhit

10-30-2008, 09:31 AM	#7 (permalink)
Benjamine1979 Junior Member Join Date: Oct 2008 Posts: 9	Re: DSL 50 overheating problems Cheers guys - the link looks like the problem

10-31-2008, 06:42 AM	#8 (permalink)
Benjamine1979 Junior Member Join Date: Oct 2008 Posts: 9	Re: DSL 100 overheating problems Hi All, So it looks like Marshall recommend to replace the main board. Is this a simple thing or would it be better to send it off to marshall?? Also has anyone recent bought a board off marshall? if so how much?? Ben

11-05-2008, 05:21 PM	#10 (permalink)
Benjamine1979 Junior Member Join Date: Oct 2008 Posts: 9	Re: DSL 50 overheating problems well, one new board later and that seems to have done the trick - 20 mins and still 90 - :-)

11-09-2008, 04:18 PM	#11 (permalink)
luekemeyer Senior Member Join Date: Nov 2008 Location: Calif Posts: 439	Re: DSL 50 overheating problems How much for the main board?

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