Rotel RA-921 Repair help. Its for a good cause

filholder · 12th April 2005, 12:41 PM

Hi i have a broken Rotel RA-921 amps. The transformer appears to be faulty since i get no output voltage from it. I cantacted rotel and they wanted £40 for a new transformer, which for a budget amp like this it not great condition is more that its worth.

Trouble one of my best mates amps has gone bad and i want to sort him out. He is skint and had a new baby arrive on sunday.

Anybody got any ideas about the VA and voltage rating for this or simlar Rotels, the RA-931 seems very similar in tnt review.

I know the VA ratinf wont be too much of an issue but if someone could tell me the voltages it would be a great help.

Fil

Gasho · 12th April 2005, 03:40 PM

Buy a good toroid transformer(Talema) of about 200VA , jus be carefull with output voltage it is about 2X20V

guytou · 12th April 2005, 10:58 PM

Hi , transformers sometimes have a thermal fuse hidden in the primary winding ,Before throwing away the old one , you may cut the protection/isolation , localize the primary winding , and try to find a continuity with a DMM . Good luck .

filholder · 12th April 2005, 11:03 PM

ok,

Cheers guys. The primal has three wire i guess his means it is a 230/115v primal which can be slip for each location. I this right?

guytou · 13th April 2005, 06:18 AM

Re -hi ,filholder ,I , in france , am not familiarized with 115 V versions ,you have only 3 wires on primary , do you have a voltage selector ?Normally , bitensions have two separate windings , i.e. 4 wires for serie/parallel connection .Maybe you could tie the primary to a tap ,but be careful ,try to understand before how the primary is wounded .How many ohms do you find between wires ?

filholder · 13th April 2005, 02:33 PM

well the leads are soldered in pins on the amp motherboard which have 230 a 115 marking so i guess it is what i thought.

No actually i have just had another look and i am wrong and dont understand thius at all. There are three leads on the primary. How does that work?

Also on the secondaries there are three winding which are thick enammleled cable and the third is thin. That doesnt make any sense. Any bosy got any ideas?

I am really confused now.

fil

12th April 2005, 12:41 PM	#1
filholder diyAudio Member Join Date: Jan 2005 Location: london	Rotel RA-921 Repair help. Its for a good cause Hi i have a broken Rotel RA-921 amps. The transformer appears to be faulty since i get no output voltage from it. I cantacted rotel and they wanted £40 for a new transformer, which for a budget amp like this it not great condition is more that its worth. Trouble one of my best mates amps has gone bad and i want to sort him out. He is skint and had a new baby arrive on sunday. Anybody got any ideas about the VA and voltage rating for this or simlar Rotels, the RA-931 seems very similar in tnt review. I know the VA ratinf wont be too much of an issue but if someone could tell me the voltages it would be a great help. Fil

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12th April 2005, 03:40 PM	#2
Gasho diyAudio Member Join Date: Nov 2004 Location: Zagreb	Buy a good toroid transformer(Talema) of about 200VA , jus be carefull with output voltage it is about 2X20V

12th April 2005, 10:58 PM	#3
guytou diyAudio Member Join Date: Mar 2005 Location: marseille	Hi , transformers sometimes have a thermal fuse hidden in the primary winding ,Before throwing away the old one , you may cut the protection/isolation , localize the primary winding , and try to find a continuity with a DMM . Good luck .

12th April 2005, 11:03 PM	#4
filholder diyAudio Member Join Date: Jan 2005 Location: london	ok, Cheers guys. The primal has three wire i guess his means it is a 230/115v primal which can be slip for each location. I this right?

13th April 2005, 06:18 AM	#5
guytou diyAudio Member Join Date: Mar 2005 Location: marseille	Re -hi ,filholder ,I , in france , am not familiarized with 115 V versions ,you have only 3 wires on primary , do you have a voltage selector ?Normally , bitensions have two separate windings , i.e. 4 wires for serie/parallel connection .Maybe you could tie the primary to a tap ,but be careful ,try to understand before how the primary is wounded .How many ohms do you find between wires ?

13th April 2005, 02:33 PM	#6
filholder diyAudio Member Join Date: Jan 2005 Location: london	well the leads are soldered in pins on the amp motherboard which have 230 a 115 marking so i guess it is what i thought. No actually i have just had another look and i am wrong and dont understand thius at all. There are three leads on the primary. How does that work? Also on the secondaries there are three winding which are thick enammleled cable and the third is thin. That doesnt make any sense. Any bosy got any ideas? I am really confused now. fil