Hi
I badly need your assistance as I am struggling with this problem for almost a month. This recorder belongs to a very close friend of mine. Originally it had a problem with both channels, poor recording level and muffle sound. I told him that I work on amplifiers only but he insisted that I have to get it done , as there is no other place locally who can get it done. Firstly I downloaded the service manual and followed the instructions. Then I replaced each and every single electrolytic capacitor on this machine including the 4 big power supply filter caps(22000uf/10000uf). According to the manual, you have to do some preparations and pre alignments before using the calibration tape. To match the external levels to the internal levels, I used my frequency generator,set to 1khz and adjusted the signal level to 0db by using a DMM to get 0.775v AC (as my generator has no output level indicator). Connected the signal to individual inputs and adjusted the levels to 0db at TP7. Next I adjusted the individual outputs to 0db. The next is adjusting the erase head current. I connected my DMM and Analog multimeter to TP2(ground) and TP4, set R139 (erase head voltage pot) to minimum and adjust T3 to get a minimum voltage on TP4. I could not get any significant voltage here, I dont see any voltage change on the meters as I tune T3. Then connect the meters to TP2 and TP3 and tried to adjust R139 to 44V (as indicated in manual). Here the maximum reading I can get is approx 7.3V and eventually stabilises at approx 6.4V. I do not understand why I am not getting the 44V.
This morning, I wanted to try something. I set R139 pots(ersase voltage) for both channels fully clockwise and did a recording. There is a time delay approx 1min for the left channel and 1.3min for the right channel,at this point I can see the +6db peak indicator flash for a split second and the sound becomes very clear on both channels but at this point I can also hear slightly the previous recording behind the present recording. I have a feeling that, the circuits around the FET can be the reason for the absence of 44V for the erase head. If anyone is familiar and worked on a Studer before, please assist me.
Thanks
Carlos
I badly need your assistance as I am struggling with this problem for almost a month. This recorder belongs to a very close friend of mine. Originally it had a problem with both channels, poor recording level and muffle sound. I told him that I work on amplifiers only but he insisted that I have to get it done , as there is no other place locally who can get it done. Firstly I downloaded the service manual and followed the instructions. Then I replaced each and every single electrolytic capacitor on this machine including the 4 big power supply filter caps(22000uf/10000uf). According to the manual, you have to do some preparations and pre alignments before using the calibration tape. To match the external levels to the internal levels, I used my frequency generator,set to 1khz and adjusted the signal level to 0db by using a DMM to get 0.775v AC (as my generator has no output level indicator). Connected the signal to individual inputs and adjusted the levels to 0db at TP7. Next I adjusted the individual outputs to 0db. The next is adjusting the erase head current. I connected my DMM and Analog multimeter to TP2(ground) and TP4, set R139 (erase head voltage pot) to minimum and adjust T3 to get a minimum voltage on TP4. I could not get any significant voltage here, I dont see any voltage change on the meters as I tune T3. Then connect the meters to TP2 and TP3 and tried to adjust R139 to 44V (as indicated in manual). Here the maximum reading I can get is approx 7.3V and eventually stabilises at approx 6.4V. I do not understand why I am not getting the 44V.
This morning, I wanted to try something. I set R139 pots(ersase voltage) for both channels fully clockwise and did a recording. There is a time delay approx 1min for the left channel and 1.3min for the right channel,at this point I can see the +6db peak indicator flash for a split second and the sound becomes very clear on both channels but at this point I can also hear slightly the previous recording behind the present recording. I have a feeling that, the circuits around the FET can be the reason for the absence of 44V for the erase head. If anyone is familiar and worked on a Studer before, please assist me.
Thanks
Carlos
Posting part of the schematic would make it much easier to figure out what is going on.
An inexpensive multimeter is not going to have the bandwidth to measure erase/bias voltage as this is probably in the range of 70 - 100kHz. You need to use a scope to do this adjustment unless you can get a meter with the bandwidth. (0f the six meters I own I have one that can do this task)
An inexpensive multimeter is not going to have the bandwidth to measure erase/bias voltage as this is probably in the range of 70 - 100kHz. You need to use a scope to do this adjustment unless you can get a meter with the bandwidth. (0f the six meters I own I have one that can do this task)
Tapeheads.net
I recently acquired a Studer A810 which due to its age I wanted to have thoroughly gone through. I searched on the forum tapeheads.net and found there several people with a lot of Studer experience. I communicated with and sent my deck out to a tech in LA. His name is Marc Bischoff and his forum ID is Tinman. He was very helpful and very knowledgable and experienced with the Studer decks in particular. You might reach out to him on the forum and he and other guys will certainly provide some assistance.
I recently acquired a Studer A810 which due to its age I wanted to have thoroughly gone through. I searched on the forum tapeheads.net and found there several people with a lot of Studer experience. I communicated with and sent my deck out to a tech in LA. His name is Marc Bischoff and his forum ID is Tinman. He was very helpful and very knowledgable and experienced with the Studer decks in particular. You might reach out to him on the forum and he and other guys will certainly provide some assistance.
Tinman was a constant Curtpalme forum member when we had those big 3 eyed CRT monsters
He was a specialist with the NEC projectors and I had 2- 6pg+,s and an XG 135. Quite helpful with those because they were hard to set up right.
Lives rather close by as I remember
Small world..,.
Regards
David
He was a specialist with the NEC projectors and I had 2- 6pg+,s and an XG 135. Quite helpful with those because they were hard to set up right.
Lives rather close by as I remember
Small world..,.
Regards
David
the forum tapeheads.net
.....I would second this recommendation, proved a helpful site when I had Teac r2r issues.
.....I would second this recommendation, proved a helpful site when I had Teac r2r issues.
Tinman has proven very generous with his time and good advice. My Studer is still with him as he has been quite busy with jobs. Given what I have seen of his postings and the extra assistance he gave me, I am very comfortable that he will do a great job on my deck. He clearly has strong familiarity and expertise with Studer a810 and a807 tape decks.
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